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Kizildere geothermal field — Western Anatolia
Geothermics (:97o) - SPECIALISSUE 2 U. N. Symposium on the Development and Utilization of Geothermal Resources, Pisa t97o. Vol. z, Part x
Kizildere Geothermal Field - W e s t e r n Anatolia A. TEN DAM * ^NO C. ERENT6Z **
ABSTRACT In the framework of the geothermal energy survey of the western Anatolia Project, sponsored by the Mineral Research and Exploration Institute of Turkey and the United Nations, a geothermal field of apparently commercially exploitable size was discovered in the Sarayktiy-Denizli geotherma! area, western Anatolia, in the year 1968. Geological, gravity and resistivity surveys of the area had been undertaken by the Mineral Research and Exploration Institute of Turkey prior to the implementation of the Project in 1967. Additional resistivity, seismic and gradient surveys, geological and geochemical investigations, resulted in the location of a first geothermal testwell. The KD No. I well was drilled in spring 1968 and became the discovery well of the Kizildere field. The wells drilled in the Kizildere geothermal field area indicate that this field can produce a mixed geothermal flow from which steam can be flashed off in commercial quantities. Production is from fractured Lower Miocene limestones, below an argillaceous caproek and from the metamorphic basement composed of schists and dolomites. The Kizildere geothermal field is located on a vositive fault block complex on the north flank of the Big Meander graben and production has already been established on several fault blocks. The structure of the Kizildere field area is fully confirmed by resistivity surveys. The Kizildere field area is characterized by geothermal gradients between 3 and 5 °C/10 m. This field has been discovered by rigorous avvlication of geological, geophysical and geochemical investigations of an area where there is no recent volcanic activity, but only some hot svrings.
Six deep testwells have been completed on this field, to date, all producing a mixed flow. At nresent, accurate mass and steam flow measurements indicate that one of the. wells has a potential of 30 t/h of dry steam, and 250 t/h of hot water at a wellhead pressure of 4 to 5 ata. Stabilized reservoir temperatures are between 185 and 200 °C. The Turkish Government is planning, to set uv as soon as oossible a oilot geothermal electric plant near o_ne or two of the most productive wells.
Introduction The Kizildere Izeothermal field was discovered in 1968 and is located in the Denizli and Aydin provinces of western Turkey. The field lies north of the Bilz Meander river between ¢ubukdag and Sarayk6y, approximately 250 kilometers by road from the city of Izmir. The field is situated in the northern part of a large hypertherrnal area which occupies the eastern part of the Big Meander and C iiriiksu river, and there are gra* Manager, SCEP. 90 Av. Champs Elys~es, 75 - Paris 8e, France. ** Petroleum and Natural Gas Department, MTA Institute, Ankara, Turkey.
124
ben complexes characterized by crossing NE-SW and NW-SE striking fault systems. This graben complex is one of several E-W. WNWESE and WSW-ENE striking graben zones in the Menderes massif. The field geological work was carried out by H. UYSALLI and his collaborators of the M.T.A. Institute. H. UYSALLI will be reporting on the geology of the Sarayk6y-Denizli geothermal area elsewhere in this Symposium. The gravity and resistivity work in the Sarayk6yDenizli geothermal area was carried out by S. KAVLAKOGLU and K. TEZCAN and their collaborators of the M.T.A. Institute. A. DUPRAT is reporting on the contribution of geophysics to the study of the Sarayk6yDenizli geothermal area. The geothermal gradient work in the framework of the UN Project was carried out by M. Dr~MIR6RER and his collaborators of the M.T.A. Institute and he will be reporting on his worke in this Symposium. The field geochemical study for the UN Project was carried out by E. DOMINCO, who also is contributing to the Symposium. The drilling operations for the Project were carded out by the M.T.A. Institute under the direction of G. FABBRETTI, P. K. SVERRISSON, G. ERGOL and G, BILIR. The production testing was carried out by G. SESTINI.
The Project has in addition benefitted from the technical advise of G. FACCA, G. MARINELLI, F, TONANI, 1. BANWELL, J. HEALY, I. ELLIS, I. INNES, F. IN-
NOCENTI and M. DI PAOLA.
Geothermal exploration history It is undoubtedly to the merit of the Rome Conference on New Sources of Energy in 1961, that it has generated an interest in the geothermal possibilities of Turkey. As of 1962, a beginning was made with the collection of basic data for geothermal exploration in Turkey by the Mineral Research and Exploration Institute of Turkey. Between 1962 and 1967 the M.T.A. Institute carried out geological and geophysical fieldwork in several of the most important hot spring area¢ in western Turkey.
Detailed geological, resistivity, gravity, magnetic and some gradient work was carried out in the Kozakli area, west of the city of Kayseri, in the SaraykSy-Denizli area, in the Simav-Sindirgi area, in the Gtinen area and in the Tuzla-Kestanbol area. In 1966 the Government of Turkey applied for a Special Fund Project for geothermal exploration in western Anatolia and in lanuary 1967 the geothermal energy survey of western Anatolia Project, sponsored by the Mineral Research and Exploration Institute and the United Nations, became operational. •
,
,
,
,
,
ing out, discharging a mixed geothermal flow with up tO 15 percent steam. After the discovery of a geothermal field at Kizildere, five additional wells were completed in this field. At the time of this paper, evaluation drilling on the Kizildere geothermal field is still going on (1). Geology of the Kizfldere geothermal field The detailed geological study of the Kizildere field area was carried out by H. UYSALLI and his staff (Figure 1).
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FiG. 1. - - K i z i l d e r e g e o t h e r m a l ]ield - are(~l geology.
After having drilled a series of control gradient holes in the Kozakli area, which indicated relatively low geothermal gradients, most of the exploratory activity of the Project was concentrated on the Sarayk6y-Denizli area. In this area both on the Tekke Hamam and Kizildere prospects, rather high geothermal gradients were encountered which raised the hope that a hot water acquifer would be present at depth. After carrying out a detailed geochemical survey and drilling a series of gradient wells, a first deep geothermal test was sited and drilled, the Kizildere No. I geothermal t.est. On 12 May 1968 this well began blow-
STRATIGRAPHY
Crystalline basement. The oldest rocks outcropping in the Kizildere field area are the gneiss series of the Menderes massif• They outcrop on the rugged mountains north of the Kizildere fault block complex. These rocks have not been encountered in any of the deep geothermal tests but have been penetrated in a gradient well, drilled near the village of Kizildere, west of the Kizildere fault block complex. (z) Till September 1970 five additional wells were drilled, three of which commercial producers, one non commercial or marginal producer and only one dry hole.
125
It is known that elsewhere in the Menderes massif the gneiss series is overlain by a less metamorphic series composed of micaschists and quarzschists with occasional boudinated marble streaks. Locally this less metamorphic series is terminated by a massive marble complex. In the Kizildere field, only the Kizildere No. 111 has penetrated over 200 meters of heavily fractured and permeable micaschists and quartzitic schists with partly boudinated marble streaks, below the Mio-Pliocene series. The crystalline schists as a whole are not outcropping on the surface in this part of the north flank of the Big Meander graben. Elsewhere, and on the south flank, they have also been found in outcrop. It had been assumed that these marbles, schists and gneisses, if sufficiently fractured, can constitute a prospective reservoir (aquifer) for geothermal exploration. As a matter of fact consich~rable permeability was c:lcountered in the schistose series in the KD No. 111 well.
Mio-Pliocene. The Mio-Pliocene series is mainly composed of two or more cycles of fluviatile and lacustrine sediments, with only very little influx of brackish water. Age determinations are approximate, but there is evidence that what is generally considered as Miocene is separated from the Pliocene by a disconformity due to vertical movements of the graben complex. Except for the basal part of the Miocene, the MioPliocene series are well exposed on the surface. At the end of the Oligocene, subsidence apparently started in the Menderes-¢i.iriiksu graben complex in the Sarayk6y-Denizli area. The Miocene sedimentary series in the Kizildere field area starts with up to 230 meters of grey and brick red varicoloured argillaceous conglomerates and sandstones at the base, passing into varicoloured marls, mudstones and siltstones, with occasional intercalations of lacustrine limestone and sandstone, or rarely some anhydrite. This series is transgressive over the cristalline basement. It is essentially an impervious complex, with possibly some limited porosity in the sandy and conglomeratic parts. This part of the Miocene sequence has been penetrated in the KD No. 111 well and did not show any permeability. It was encountered in five additional wells. The lowermost Miocene clastic series is overlain by up to 175 meters of grey to buff colored, hard, fractured and cavernous limestones, with occasional silicifled pans, especially towards the top. This limestone series is characterized by fresh water to occasional brackish water Ostracods and is almost entirely lacustrine. These limestones show generally a strong fracture permeability, except where affected by silicization. This limestone series constitutes the first reservoir 126
of the Kizildere field and has been penetrated in all its thickness only in the KD No. IV well. The other wells were stopped in the upper part of this aquifer, except for the KD No. 111 well where the basal 74 meters were encount.ered only, as the limestones are outcropping in this area. There is now evidence that this limestone may have a lenticular character and wedges out towards the centre of the graben complex. The Lower Miocene limestone series is overlain by 400 to 600 meters of Upper and Middle Miocene argillaceous and marly argillaceous sediments. The lower part of this caprock series is generally composed of marls and argillaceous marls with streaks and intercalations of argillaceous sandstone and siltstone. The basal part of this marly argillaceous lower portion of the Miocene caprock series passes locally into a series of siltstones and argillaceous siltstones. Thin limestone streaks have been encountered locally. Towards the top, this grey coloured marly-argillaceous series passes into a more argillaceous series, occasionally with plastic clays, but also with thin sandy or silty streaks. The lower part measures between 150 to 250 m; in the upper part between 270 and 370 m. The total thickness of this series is variable due to depositional conditions and to the fact that vertical movements took place at the end of the Miocene, so that the Pliocene is disconformable and transgressive over the' Miocene. Considerable gravity sliding has taken place in this plastic argillaceous complex so that well to well correlation in this lacustrine series is often rather difficult. The Pliocene lacustrine beds are disconformably overlying the Upper Middle Miocene argillaceous and marly argillaceous series. The Pliocene generally starts with up to 100 meters of argillaceous conglomerates and sandstones followed by marls. These are followed by some 25 meters of anhydritic gypsiferous marls and argillaceous marls. This series is variable in thickness and extension. This lower part of the Pliocene is overlain by 80 meters of limestones and sandy limestones, 30 to 40 meters of argillaceous sandstones, up to 100 meters of argillaceous conglomerates, sandstones, clays and marls and 100 to 150 meters of clays and soft sandstones. This Pliocene series is extensively exposed on the east and northeast flank of the Kizildere fauhblock complex, and has locally been found in depressions, also in the northern part of the structure. Due to gravity sliding of Pliocene limestones over the plastic part of the Miocene, the outcrops are sometimes rather chaotic. Of the deep test wells, only d" .~ KD No. III and No. IV wells have encountered sor,~ 100 meters of the lower part of the Pliocene i.e. sandstones at the base and overlying limestones. The Pliocene does not show any strong permeabilities and has to be considered as essentially imperviov.s.
Quaternary. Most of the Kizildere field is outcropping in the Mio-Pliocene series, and Quaternary alluvia only occur on the lowermost fault blocks, towards the centre of the Big Meander graben complex. There are generally finely grained silty and sandysilty alluvia with much argillaceous material. Its thickness is a few tens of meters on the lower fault blocks of the Kizildere field and possibly up to several hundreds of meters in the deeper parts of the Big Menderes~i.iriiksu graben complex.
There are locally a few outcrops of Quaternary travertines in the Kizildere field area, associated with the hot springs. STRUCTURE
The Kizildere field is essentially constituted by a block-faulted uplift on the northern flank of the Big Meander-(~tiriiksu graben complex. It is an E-W striking complex positive structure, stepfaulting down to the south, to the center of the Big Meander graben and
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morly-orgilloceous s e r i a l - FIRST CAPROCK
MIOCENE - limestone,froctured -FIRST RESERVOIR NIOCENE - voricolored detritics -SECOND CAPROCK CRISTALLINE BASEMENT-schists with m@rble straoks, froctured- SECOND RESERVOIR FIo.
2.
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Kizildere geothermal /ield . cross sections.
127~
stepping somewhat down to the Mio-Pliocene crystalline fault contact in the north. The surface geology indicates a series of roughly east-west and northeast-southwest striking fault zones, whereas gradient wells indicate that one of two more east-west striking step-faults separate the Kizildere uplift from the center of the Big Meander graben. Twc~ fault-blocks on the axis of the Kizildere uplift have the fractured limestones of the Lower Miocene exposed. All others fault-blocks are exposed on the Mio-Pliocene series. The contact of the Pliocene series with the crystalline basement on the north flank of the Kizildere positive structure is by a major graben fault. The dips in the more or less plastic marly-argil-" laceous Mio-Pliocene series are rather erratic and may be rather steep close to faultzones. In addition this series is affected by severe gravity sliding and slumping partly du to frequent vertical tectonic movements during deposition and partly due to the very frequent recent vertical and horizontal movements. As a matter of fact the Kizildere field is situated in one of the most active seismic zones of western Anatolia and it is thought that fractures in the aquifers are being kept open by continuous tectonic movements and seismicity. The interpretation of the resistivity survey by A. DUPRAT, however, appears to indicate that below the more or less plastic and irregular sliding cover of Mio?liocene argillaceous beds, the Lower Miocene limestone series is affected by a series of NW-SE and E-W to WSW-ENE striking faults which show up on the resistivity as distinct electric discontinuities. CONCLUSIONS It appears evident that the Mio-Pliocene predomiaantly marly argillaceous series acts as an efficient impervious caprock, covering the Lower Miocene fractured limestone reservoir, the first exploration objective. It is also clear that the lowermost Lower Miocene elastic series represents a second deeper caprock series separating the Lower Miocene limestone reservoir from the underlying second aquifer in the fractured crystalline basement, partly composed of marbles. These assumptions made at the beginning of the exploration programme in the Kizildere area have been confirmed by deep drilling. There are definitely two impervious series acting as cap rocks: the Mio-Pliocene argillaceous series sealing off the Lower Miocene limestones, and the lowermost Lower Miocene varicoloured elastics separating the first payzone from the fractured crystalline basement. Indications of a b n o r m a l h e a t flow
The hyperthermal indications in the Saraykry-Denizli area and the results of the gradient measurements on the various structures in this geothermal area, have 128
been described in papers by E. DOMINCO and M. DEM1RORER as well as referred to in the paper by A. DUPRAT. There are a great number of small hot springs with water up to 100°C, issuing on minor and major fault zones, particularly on the south flank of the Kizildere uplift and some small steam vents higher up on the Kizildere fault block complex. There are a total of over 60 geothermal gradient wells of approximately 100 m depth and in the impervious argillaceous caprock series. There is an area covering about 10 km ~ where the geothermal gradient in the first 100 m of impervious caprock is in excess of 3°C/10 m and where bottom-hole temperatures at 100 m depth are in excess of 45 °c. It is unlikely that these gradients continue rectilinearly to the top of the first aquifer and there is evidence that they decrease somewhat with depth. Also some of the gradient values may be influenced by the presence of nearby hot spring systems, althoug!a, the location of gradient wells near hot springs has been avoided as much as possible. The isogradient-curves and the isotherms at 100 m depth fit in very well with the known geological structure. Assuming a uniform base temperature in the first aquifer of 200°C and a rectilinear gradient, the temperature figures again give contours on top of the first payzone which fit in rather well with the geology and with the wells hitherto drilled. The assumption of a base temperature cf 200°C in the first aquifer has been confirmed by the KD No. IA well. There is, however, some evidence that basetemperatures in the first aquifer may be somewhat lower on the higher fault blocks. This had not been checked in detail when this paper was being prepared. There is, however, some evidence in the comparison of the gradient results with the resistivity interpretation of A. DUPRAT, that the highest base temperatures in the first reservoir may be found on the stepfault blocks on the south flank of the Kizildere structure. It is therefore in this area that present evaluation work is continuing. This may therefore indicate that the hot water in the first Kizildere reservoir is locally diluted with colder ground-waters of which the origin is not known. Deep boreholes
During the years 1968 and 1969, a total of six deep test wells were drilled on the Kizildere thermal anomaly: Well number
KD KD KD KD KD KD
No. No. No. No. No. No.
I If IA III IV 111
Spudded in
20 Apr 16 Sep 17 lan 26 Mar 7 May 1 lul
1968 1968 1969 1969 1969 1969
Completed
12 May 18 Nov 15 Feb 25 Apr 26 Oct 8 Sep
1968 1968 1969 1969 1969 1969
Total Depth
448.90m 706.50 m 451.50m 370 m 486 m 504.85 m
All six wells were brought in as producers of mixe: geothermal fluid, generally flashing off in the casing. Total mass flows and separable steam have only been measured in the best of these six wells KD No. IA: 18 t / h dry steam from flashing 143 t / h hot water
.
.,.
,
at a wellhead pressure of 9.5 ata (1). These measurements were on an incrustated well and it is estimated that clean wells can produce up to: 30 t / h dry steam from flashing 250 t / h hot water at an operating pressure of 4 to 5 ata. Wells drilled since the end of 1969 show total mass flows of up to 400 t/h of hot water with 8 % of steam at 6 ata wellhead pressure.
peratures in the fractured limestone reservoir than the KD No. II and No. III wells. At present, evaluation drilling is in process on the KD No. I fault-block. The mass flow conditions measured on the KD No. IA well indicate a base temperature between 185 and 200 °C in the fractured limestone reservoir. This was later confirmed by down-hole measurements. The various wells penetrated as in Table 1. The high permeability of the fractured limestone series is indicated by the fact that while drilling, there are no returns of drilling fluid to the surface, and up to 30-40 tons of fluid have been lost. The geothermal fluid in the Kizildere field is noncorrosive, but gives rise to serious calcite incrustation, mostly in the production casing, where most of the flashing takes place. These incrustations have to be removed by a small servicing rig at periodic intervals.
TABLE1. -- Wells drilled in Kizildere /ield.
Ist Caprock
Reservoir 2nd Caprock Reser. voir
Formations (depth in m below RT)
KD I
KD IA
KD II
KD III
KD IV
Pliocene Upper, Middle, Miocene
0-436 m
0-429 m
0-651 m
0-113 m 113-242 m
0-20 m 26-313m
429-451.50 m
651-700.50m
242-370m
313-485 m
0-74 m
485-486 m
74-301 m
Lower Miocene (limestone) Lower Miocene (elastics) Cristalline basement
436-448.90 m ..... :
- -"
::
KD KD KD KD KD
I II III IV 111
300 .80 60 300 25
t/h t/h t/h t/h t/h
The dry steam obtained from the separator set on the KD No. IA well contains 5-6 percent non-condensable gases, no corrosives and could be used directly in a low pressure turbine-generator. Those produciiag from the basement appear to ha,~e a much higher CO~ content. There appears to be evidence that the KID, No. I, IA and IV are tapping fault-blocks with higher tern-
(1) 1 ata-- 1 kg/cm: abs.
301-504.85 m
.
Rough estimates of the total mass flow in the other wells are as follows:
KD 111
The chemical composition of the geothermal fluids of the Kizildere wells is being discussed in a paper by E. DOMrNCO and E. SAMILGXL.
Conclusions A survey composed of extensive geological, geophysical and.geochemical exploration, followed by deep drilling i n t h e Sarayk6y-Denizli area has resulted in the discovery of a geothermal field. The Kizildere geothermal field is for the time being a hot water field, from which steam can be obtained by flashing. It appears that wells in this field, especially on the lower fault-blocks can make up to 32 tons of dry steam per hour and up to 400 tons of hot water at operating pressures between 5 and 6 ata. It has been established that the deeper fractured reservoir, in the crystalline basement, mainly composed of marbles, constitutes the main reservoir in this field, with a secondary, higher reservoir made up by the Mio-Pliocene limestones.
129
Kizildere Geothermal Field - W e s t e r n Anatolia A. TEN DAM * ^NO C. ERENT6Z **
ABSTRACT In the framework of the geothermal energy survey of the western Anatolia Project, sponsored by the Mineral Research and Exploration Institute of Turkey and the United Nations, a geothermal field of apparently commercially exploitable size was discovered in the Sarayktiy-Denizli geotherma! area, western Anatolia, in the year 1968. Geological, gravity and resistivity surveys of the area had been undertaken by the Mineral Research and Exploration Institute of Turkey prior to the implementation of the Project in 1967. Additional resistivity, seismic and gradient surveys, geological and geochemical investigations, resulted in the location of a first geothermal testwell. The KD No. I well was drilled in spring 1968 and became the discovery well of the Kizildere field. The wells drilled in the Kizildere geothermal field area indicate that this field can produce a mixed geothermal flow from which steam can be flashed off in commercial quantities. Production is from fractured Lower Miocene limestones, below an argillaceous caproek and from the metamorphic basement composed of schists and dolomites. The Kizildere geothermal field is located on a vositive fault block complex on the north flank of the Big Meander graben and production has already been established on several fault blocks. The structure of the Kizildere field area is fully confirmed by resistivity surveys. The Kizildere field area is characterized by geothermal gradients between 3 and 5 °C/10 m. This field has been discovered by rigorous avvlication of geological, geophysical and geochemical investigations of an area where there is no recent volcanic activity, but only some hot svrings.
Six deep testwells have been completed on this field, to date, all producing a mixed flow. At nresent, accurate mass and steam flow measurements indicate that one of the. wells has a potential of 30 t/h of dry steam, and 250 t/h of hot water at a wellhead pressure of 4 to 5 ata. Stabilized reservoir temperatures are between 185 and 200 °C. The Turkish Government is planning, to set uv as soon as oossible a oilot geothermal electric plant near o_ne or two of the most productive wells.
Introduction The Kizildere Izeothermal field was discovered in 1968 and is located in the Denizli and Aydin provinces of western Turkey. The field lies north of the Bilz Meander river between ¢ubukdag and Sarayk6y, approximately 250 kilometers by road from the city of Izmir. The field is situated in the northern part of a large hypertherrnal area which occupies the eastern part of the Big Meander and C iiriiksu river, and there are gra* Manager, SCEP. 90 Av. Champs Elys~es, 75 - Paris 8e, France. ** Petroleum and Natural Gas Department, MTA Institute, Ankara, Turkey.
124
ben complexes characterized by crossing NE-SW and NW-SE striking fault systems. This graben complex is one of several E-W. WNWESE and WSW-ENE striking graben zones in the Menderes massif. The field geological work was carried out by H. UYSALLI and his collaborators of the M.T.A. Institute. H. UYSALLI will be reporting on the geology of the Sarayk6y-Denizli geothermal area elsewhere in this Symposium. The gravity and resistivity work in the Sarayk6yDenizli geothermal area was carried out by S. KAVLAKOGLU and K. TEZCAN and their collaborators of the M.T.A. Institute. A. DUPRAT is reporting on the contribution of geophysics to the study of the Sarayk6yDenizli geothermal area. The geothermal gradient work in the framework of the UN Project was carried out by M. Dr~MIR6RER and his collaborators of the M.T.A. Institute and he will be reporting on his worke in this Symposium. The field geochemical study for the UN Project was carried out by E. DOMINCO, who also is contributing to the Symposium. The drilling operations for the Project were carded out by the M.T.A. Institute under the direction of G. FABBRETTI, P. K. SVERRISSON, G. ERGOL and G, BILIR. The production testing was carried out by G. SESTINI.
The Project has in addition benefitted from the technical advise of G. FACCA, G. MARINELLI, F, TONANI, 1. BANWELL, J. HEALY, I. ELLIS, I. INNES, F. IN-
NOCENTI and M. DI PAOLA.
Geothermal exploration history It is undoubtedly to the merit of the Rome Conference on New Sources of Energy in 1961, that it has generated an interest in the geothermal possibilities of Turkey. As of 1962, a beginning was made with the collection of basic data for geothermal exploration in Turkey by the Mineral Research and Exploration Institute of Turkey. Between 1962 and 1967 the M.T.A. Institute carried out geological and geophysical fieldwork in several of the most important hot spring area¢ in western Turkey.
Detailed geological, resistivity, gravity, magnetic and some gradient work was carried out in the Kozakli area, west of the city of Kayseri, in the SaraykSy-Denizli area, in the Simav-Sindirgi area, in the Gtinen area and in the Tuzla-Kestanbol area. In 1966 the Government of Turkey applied for a Special Fund Project for geothermal exploration in western Anatolia and in lanuary 1967 the geothermal energy survey of western Anatolia Project, sponsored by the Mineral Research and Exploration Institute and the United Nations, became operational. •
,
,
,
,
,
ing out, discharging a mixed geothermal flow with up tO 15 percent steam. After the discovery of a geothermal field at Kizildere, five additional wells were completed in this field. At the time of this paper, evaluation drilling on the Kizildere geothermal field is still going on (1). Geology of the Kizfldere geothermal field The detailed geological study of the Kizildere field area was carried out by H. UYSALLI and his staff (Figure 1).
/ .,.[_
LEGEND MMI~'III
"l'X
~
m
~
~
,t-
"-r-//~i
-I-
fiVlr
OIIUViU~
P L t O C I r N E - clonNnontly d e t r i t i c s MIOC(NE
-mOtiy-CWQillOC4OQI
MIOCENE * froclulld
ilrM
ii~mZt~
C R I S T A L L I NE B A S E M E N T
+
,+
@
,,~
YD 3~Om
9
SCALE , xo ,ooo
FiG. 1. - - K i z i l d e r e g e o t h e r m a l ]ield - are(~l geology.
After having drilled a series of control gradient holes in the Kozakli area, which indicated relatively low geothermal gradients, most of the exploratory activity of the Project was concentrated on the Sarayk6y-Denizli area. In this area both on the Tekke Hamam and Kizildere prospects, rather high geothermal gradients were encountered which raised the hope that a hot water acquifer would be present at depth. After carrying out a detailed geochemical survey and drilling a series of gradient wells, a first deep geothermal test was sited and drilled, the Kizildere No. I geothermal t.est. On 12 May 1968 this well began blow-
STRATIGRAPHY
Crystalline basement. The oldest rocks outcropping in the Kizildere field area are the gneiss series of the Menderes massif• They outcrop on the rugged mountains north of the Kizildere fault block complex. These rocks have not been encountered in any of the deep geothermal tests but have been penetrated in a gradient well, drilled near the village of Kizildere, west of the Kizildere fault block complex. (z) Till September 1970 five additional wells were drilled, three of which commercial producers, one non commercial or marginal producer and only one dry hole.
125
It is known that elsewhere in the Menderes massif the gneiss series is overlain by a less metamorphic series composed of micaschists and quarzschists with occasional boudinated marble streaks. Locally this less metamorphic series is terminated by a massive marble complex. In the Kizildere field, only the Kizildere No. 111 has penetrated over 200 meters of heavily fractured and permeable micaschists and quartzitic schists with partly boudinated marble streaks, below the Mio-Pliocene series. The crystalline schists as a whole are not outcropping on the surface in this part of the north flank of the Big Meander graben. Elsewhere, and on the south flank, they have also been found in outcrop. It had been assumed that these marbles, schists and gneisses, if sufficiently fractured, can constitute a prospective reservoir (aquifer) for geothermal exploration. As a matter of fact consich~rable permeability was c:lcountered in the schistose series in the KD No. 111 well.
Mio-Pliocene. The Mio-Pliocene series is mainly composed of two or more cycles of fluviatile and lacustrine sediments, with only very little influx of brackish water. Age determinations are approximate, but there is evidence that what is generally considered as Miocene is separated from the Pliocene by a disconformity due to vertical movements of the graben complex. Except for the basal part of the Miocene, the MioPliocene series are well exposed on the surface. At the end of the Oligocene, subsidence apparently started in the Menderes-¢i.iriiksu graben complex in the Sarayk6y-Denizli area. The Miocene sedimentary series in the Kizildere field area starts with up to 230 meters of grey and brick red varicoloured argillaceous conglomerates and sandstones at the base, passing into varicoloured marls, mudstones and siltstones, with occasional intercalations of lacustrine limestone and sandstone, or rarely some anhydrite. This series is transgressive over the cristalline basement. It is essentially an impervious complex, with possibly some limited porosity in the sandy and conglomeratic parts. This part of the Miocene sequence has been penetrated in the KD No. 111 well and did not show any permeability. It was encountered in five additional wells. The lowermost Miocene clastic series is overlain by up to 175 meters of grey to buff colored, hard, fractured and cavernous limestones, with occasional silicifled pans, especially towards the top. This limestone series is characterized by fresh water to occasional brackish water Ostracods and is almost entirely lacustrine. These limestones show generally a strong fracture permeability, except where affected by silicization. This limestone series constitutes the first reservoir 126
of the Kizildere field and has been penetrated in all its thickness only in the KD No. IV well. The other wells were stopped in the upper part of this aquifer, except for the KD No. 111 well where the basal 74 meters were encount.ered only, as the limestones are outcropping in this area. There is now evidence that this limestone may have a lenticular character and wedges out towards the centre of the graben complex. The Lower Miocene limestone series is overlain by 400 to 600 meters of Upper and Middle Miocene argillaceous and marly argillaceous sediments. The lower part of this caprock series is generally composed of marls and argillaceous marls with streaks and intercalations of argillaceous sandstone and siltstone. The basal part of this marly argillaceous lower portion of the Miocene caprock series passes locally into a series of siltstones and argillaceous siltstones. Thin limestone streaks have been encountered locally. Towards the top, this grey coloured marly-argillaceous series passes into a more argillaceous series, occasionally with plastic clays, but also with thin sandy or silty streaks. The lower part measures between 150 to 250 m; in the upper part between 270 and 370 m. The total thickness of this series is variable due to depositional conditions and to the fact that vertical movements took place at the end of the Miocene, so that the Pliocene is disconformable and transgressive over the' Miocene. Considerable gravity sliding has taken place in this plastic argillaceous complex so that well to well correlation in this lacustrine series is often rather difficult. The Pliocene lacustrine beds are disconformably overlying the Upper Middle Miocene argillaceous and marly argillaceous series. The Pliocene generally starts with up to 100 meters of argillaceous conglomerates and sandstones followed by marls. These are followed by some 25 meters of anhydritic gypsiferous marls and argillaceous marls. This series is variable in thickness and extension. This lower part of the Pliocene is overlain by 80 meters of limestones and sandy limestones, 30 to 40 meters of argillaceous sandstones, up to 100 meters of argillaceous conglomerates, sandstones, clays and marls and 100 to 150 meters of clays and soft sandstones. This Pliocene series is extensively exposed on the east and northeast flank of the Kizildere fauhblock complex, and has locally been found in depressions, also in the northern part of the structure. Due to gravity sliding of Pliocene limestones over the plastic part of the Miocene, the outcrops are sometimes rather chaotic. Of the deep test wells, only d" .~ KD No. III and No. IV wells have encountered sor,~ 100 meters of the lower part of the Pliocene i.e. sandstones at the base and overlying limestones. The Pliocene does not show any strong permeabilities and has to be considered as essentially imperviov.s.
Quaternary. Most of the Kizildere field is outcropping in the Mio-Pliocene series, and Quaternary alluvia only occur on the lowermost fault blocks, towards the centre of the Big Meander graben complex. There are generally finely grained silty and sandysilty alluvia with much argillaceous material. Its thickness is a few tens of meters on the lower fault blocks of the Kizildere field and possibly up to several hundreds of meters in the deeper parts of the Big Menderes~i.iriiksu graben complex.
There are locally a few outcrops of Quaternary travertines in the Kizildere field area, associated with the hot springs. STRUCTURE
The Kizildere field is essentially constituted by a block-faulted uplift on the northern flank of the Big Meander-(~tiriiksu graben complex. It is an E-W striking complex positive structure, stepfaulting down to the south, to the center of the Big Meander graben and
W
E
KD "n'r j ~ . . , - _ _ ,
,
~ t
KD 111 A Ill I t
l--r
i i "t
KD ]~" A
t:~il~-..~
+ 500m
+,ooo
- 250 .m
- 500 m
N
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.
t
- o-
250
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- 500.
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-750 m
KD~
XJ '
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. ~ S
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4" 250 m --0 - 250 m
-500 m ~
~~ ' ~ ' ~ ' ~/J J J / / J ~ /~/
_
-
750 m
- , o o o m
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I
I
50O
I
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PUOCENE - CalXock MIOCENE
morly-orgilloceous s e r i a l - FIRST CAPROCK
MIOCENE - limestone,froctured -FIRST RESERVOIR NIOCENE - voricolored detritics -SECOND CAPROCK CRISTALLINE BASEMENT-schists with m@rble straoks, froctured- SECOND RESERVOIR FIo.
2.
--
Kizildere geothermal /ield . cross sections.
127~
stepping somewhat down to the Mio-Pliocene crystalline fault contact in the north. The surface geology indicates a series of roughly east-west and northeast-southwest striking fault zones, whereas gradient wells indicate that one of two more east-west striking step-faults separate the Kizildere uplift from the center of the Big Meander graben. Twc~ fault-blocks on the axis of the Kizildere uplift have the fractured limestones of the Lower Miocene exposed. All others fault-blocks are exposed on the Mio-Pliocene series. The contact of the Pliocene series with the crystalline basement on the north flank of the Kizildere positive structure is by a major graben fault. The dips in the more or less plastic marly-argil-" laceous Mio-Pliocene series are rather erratic and may be rather steep close to faultzones. In addition this series is affected by severe gravity sliding and slumping partly du to frequent vertical tectonic movements during deposition and partly due to the very frequent recent vertical and horizontal movements. As a matter of fact the Kizildere field is situated in one of the most active seismic zones of western Anatolia and it is thought that fractures in the aquifers are being kept open by continuous tectonic movements and seismicity. The interpretation of the resistivity survey by A. DUPRAT, however, appears to indicate that below the more or less plastic and irregular sliding cover of Mio?liocene argillaceous beds, the Lower Miocene limestone series is affected by a series of NW-SE and E-W to WSW-ENE striking faults which show up on the resistivity as distinct electric discontinuities. CONCLUSIONS It appears evident that the Mio-Pliocene predomiaantly marly argillaceous series acts as an efficient impervious caprock, covering the Lower Miocene fractured limestone reservoir, the first exploration objective. It is also clear that the lowermost Lower Miocene elastic series represents a second deeper caprock series separating the Lower Miocene limestone reservoir from the underlying second aquifer in the fractured crystalline basement, partly composed of marbles. These assumptions made at the beginning of the exploration programme in the Kizildere area have been confirmed by deep drilling. There are definitely two impervious series acting as cap rocks: the Mio-Pliocene argillaceous series sealing off the Lower Miocene limestones, and the lowermost Lower Miocene varicoloured elastics separating the first payzone from the fractured crystalline basement. Indications of a b n o r m a l h e a t flow
The hyperthermal indications in the Saraykry-Denizli area and the results of the gradient measurements on the various structures in this geothermal area, have 128
been described in papers by E. DOMINCO and M. DEM1RORER as well as referred to in the paper by A. DUPRAT. There are a great number of small hot springs with water up to 100°C, issuing on minor and major fault zones, particularly on the south flank of the Kizildere uplift and some small steam vents higher up on the Kizildere fault block complex. There are a total of over 60 geothermal gradient wells of approximately 100 m depth and in the impervious argillaceous caprock series. There is an area covering about 10 km ~ where the geothermal gradient in the first 100 m of impervious caprock is in excess of 3°C/10 m and where bottom-hole temperatures at 100 m depth are in excess of 45 °c. It is unlikely that these gradients continue rectilinearly to the top of the first aquifer and there is evidence that they decrease somewhat with depth. Also some of the gradient values may be influenced by the presence of nearby hot spring systems, althoug!a, the location of gradient wells near hot springs has been avoided as much as possible. The isogradient-curves and the isotherms at 100 m depth fit in very well with the known geological structure. Assuming a uniform base temperature in the first aquifer of 200°C and a rectilinear gradient, the temperature figures again give contours on top of the first payzone which fit in rather well with the geology and with the wells hitherto drilled. The assumption of a base temperature cf 200°C in the first aquifer has been confirmed by the KD No. IA well. There is, however, some evidence that basetemperatures in the first aquifer may be somewhat lower on the higher fault blocks. This had not been checked in detail when this paper was being prepared. There is, however, some evidence in the comparison of the gradient results with the resistivity interpretation of A. DUPRAT, that the highest base temperatures in the first reservoir may be found on the stepfault blocks on the south flank of the Kizildere structure. It is therefore in this area that present evaluation work is continuing. This may therefore indicate that the hot water in the first Kizildere reservoir is locally diluted with colder ground-waters of which the origin is not known. Deep boreholes
During the years 1968 and 1969, a total of six deep test wells were drilled on the Kizildere thermal anomaly: Well number
KD KD KD KD KD KD
No. No. No. No. No. No.
I If IA III IV 111
Spudded in
20 Apr 16 Sep 17 lan 26 Mar 7 May 1 lul
1968 1968 1969 1969 1969 1969
Completed
12 May 18 Nov 15 Feb 25 Apr 26 Oct 8 Sep
1968 1968 1969 1969 1969 1969
Total Depth
448.90m 706.50 m 451.50m 370 m 486 m 504.85 m
All six wells were brought in as producers of mixe: geothermal fluid, generally flashing off in the casing. Total mass flows and separable steam have only been measured in the best of these six wells KD No. IA: 18 t / h dry steam from flashing 143 t / h hot water
.
.,.
,
at a wellhead pressure of 9.5 ata (1). These measurements were on an incrustated well and it is estimated that clean wells can produce up to: 30 t / h dry steam from flashing 250 t / h hot water at an operating pressure of 4 to 5 ata. Wells drilled since the end of 1969 show total mass flows of up to 400 t/h of hot water with 8 % of steam at 6 ata wellhead pressure.
peratures in the fractured limestone reservoir than the KD No. II and No. III wells. At present, evaluation drilling is in process on the KD No. I fault-block. The mass flow conditions measured on the KD No. IA well indicate a base temperature between 185 and 200 °C in the fractured limestone reservoir. This was later confirmed by down-hole measurements. The various wells penetrated as in Table 1. The high permeability of the fractured limestone series is indicated by the fact that while drilling, there are no returns of drilling fluid to the surface, and up to 30-40 tons of fluid have been lost. The geothermal fluid in the Kizildere field is noncorrosive, but gives rise to serious calcite incrustation, mostly in the production casing, where most of the flashing takes place. These incrustations have to be removed by a small servicing rig at periodic intervals.
TABLE1. -- Wells drilled in Kizildere /ield.
Ist Caprock
Reservoir 2nd Caprock Reser. voir
Formations (depth in m below RT)
KD I
KD IA
KD II
KD III
KD IV
Pliocene Upper, Middle, Miocene
0-436 m
0-429 m
0-651 m
0-113 m 113-242 m
0-20 m 26-313m
429-451.50 m
651-700.50m
242-370m
313-485 m
0-74 m
485-486 m
74-301 m
Lower Miocene (limestone) Lower Miocene (elastics) Cristalline basement
436-448.90 m ..... :
- -"
::
KD KD KD KD KD
I II III IV 111
300 .80 60 300 25
t/h t/h t/h t/h t/h
The dry steam obtained from the separator set on the KD No. IA well contains 5-6 percent non-condensable gases, no corrosives and could be used directly in a low pressure turbine-generator. Those produciiag from the basement appear to ha,~e a much higher CO~ content. There appears to be evidence that the KID, No. I, IA and IV are tapping fault-blocks with higher tern-
(1) 1 ata-- 1 kg/cm: abs.
301-504.85 m
.
Rough estimates of the total mass flow in the other wells are as follows:
KD 111
The chemical composition of the geothermal fluids of the Kizildere wells is being discussed in a paper by E. DOMrNCO and E. SAMILGXL.
Conclusions A survey composed of extensive geological, geophysical and.geochemical exploration, followed by deep drilling i n t h e Sarayk6y-Denizli area has resulted in the discovery of a geothermal field. The Kizildere geothermal field is for the time being a hot water field, from which steam can be obtained by flashing. It appears that wells in this field, especially on the lower fault-blocks can make up to 32 tons of dry steam per hour and up to 400 tons of hot water at operating pressures between 5 and 6 ata. It has been established that the deeper fractured reservoir, in the crystalline basement, mainly composed of marbles, constitutes the main reservoir in this field, with a secondary, higher reservoir made up by the Mio-Pliocene limestones.
129