Carboxylic acid anions in formation waters, San Joaquin Basin and Louisiana Gulf Coast, U.S.A.—Implications for clastic diagenesis. critical comment

Applied Geochemistry, Vol. 8, pp. 305 307, 1993

0883-2927/93 $6.00+ .00 Pergamon Press Ltd

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Carboxylic acid anions in formation waters, San Joaquin Basin and Louisiana Gulf Coast, U.S.A.--Implications for clastic diagenesis. Critical Comment J. S. HANOR Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, U.S.A. L. S. LAND Department of Geological Sciences, University of Texas, Austin, TX 78712, U.S.A. and G. L, MACPHERSON Department of Geology, University of Kansas, Lawrence, KS 66045, U.S.A. (Received 24 September 1991; accepted in revised form 14 October 1992)

THE ANALYSESof carboxylic acid anions (CAAs) in San Joaquin Basin and Louisiana Gulf Coast formation waters published by MAcGOWAN and SCRDAM (1990) do little to resolve the important question of whether C A A s are of great significance to clastic diagenesis over the temperature range in which they dominate fluid alkalinity, as advocated by these two authors. Comparison of their analyses with analyses of formation waters from the same wells previously published by three independent research groups (HANORand WORKMAN,1986; LAND et al., 1988 and LAND and MACPHERSON, 1989; and FISHER and BOLES, 1990), a body of data not discussed in their article, reveals that most of the MAcGOWAN and SURDAM values are grossly inflated relative to the previous analyses (Table 1, Fig. 1).

ONSHORE LOUISIANA One example is their analysis of Louisiana Gulf Coast Basin Sample No. 19, identified by them as Point (sic.) Barre, 114, temperature 89°C. This water is apparently from the WORKMAN (1985) well, Port Barre BB-114, temperature 89°C, an onshore well in south central Louisiana. MAcGOWAN and SURDAM report a total monofunctional CCA concentration of 1260 ppm. However, an earlier analytical study of water from this same well by WORKMAN (1985) and published under well no. 31 by HANORand WORKMAN (1986) detected only 142 mg/1 total monofunctional CAAs, which is far less, even allowing for some loss of C A A s during sample preparation. It is well understood by us that preservation of formation water samples for laboratory analysis of C A A s is an important aspect of field procedures. The aliquots analyzed for C A A s by WORKMAN(1985) were preserved in the field by acidification with HC1, following the pro-

cedures of Llco et al. (1982). While field procedures for C A A s now normally include the addition of a bactericide to the sample, an independent check on the upper limit of total C A A s which could have been present in this water is provided by the results of an alkalinity titration to pH 2.5, also published by HANOR and WORKMAN (1986), which show that the total concentration of weak acid anions (bicarbonate plus C A A s ) could not have exceeded approximately 428 mg/1. The alkalinity determinations were done shortly after collection on separate, untreated aliquots stored in gas-tight glass containers. Further details are given in WORKMAN(1985).

OFFSHORE LOUISIANA

Additional examples are provided by waters from offshore Louisiana wells previously sampled and analyzed by LAND et al. (1988) and LAND and MACPHERSON (1989). Alkalinity titrations to a pH of 3 or less were accomplished within 30 min of sampling. Samples for organic acid analyses were preserved in glass with 1 ml of 0.1 M NaOH and eight drops of saturated HgC12. Samples were refrigerated within 36 h of sampling and analyzed within one week. The chromatographic separation method ( A P H A , 1976, pp. 527-529) utilized measures all of the most abundant organic acids listed in Table 2 of MAcGOWAN and SORD~. The accuracy of the technique, based on repeated analyses of a standard solution, was 12%. Precision was at least 5% and usually better than 3% (MACPHERSON,unpublished). No systematic differences were observed in analyses of splits of waters collected with and without mercuric chloride. These previously published values are 1.5 to 4 times lower than the MAcGOWAN and SURDAM values (Table 1; Fig. 1). As with the Port Barre example

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306

J.S. Hanor et HI.

Table 1. Comparison of the concentrations of total monofunctional carboxylic acid anions in San Joaquin and Louisiana Gulf Coast formation waters published by MAcGOWANand SORDAM(1990) with previously published analyses for the same wells Previously Published Analyses

MAcGOWANand SURDAM(1991) Analyses

Sample No. Louisiana 7 8 9 13 15 16 17 18 19

Field Gulf Coast Basin South Marsh Island Eugene Island Eugene Island Rabbit Island Lighthouse Point South Marsh Island South Marsh Island South Marsh Island Point Barre

San Joaquin Basin, California 1 San Emidio Nose 2 Rosedale 3 Rosedale 4 Yowlumme 5 Greely 6 Greely 7 Rio Viejo 11 Paloma 12 Paloma 13 Paloma 14 Coles Levee 15 Coles Levee 16 Kern Front 17 Kern Front 18 Rosedale Ranch 19 Kern River 21 Mt Poso

Descriptor

Tot. Mono CAAs ppm

Tot. Mono CAAs mg/1

Descriptor

Tot. Organic Acids mg/l 718 536 1608 849 1088 821 813 884

Ref.

II-BI Block 338 Block 313b 183 A-4 II 1-A II-B-3 33 114

1630 1610 5690 2750 4430 1370 1300 1370 1260

SMI ll-B-1 (E B1) E1 338 A-13 El 313 B-19 RI 183 (D 183) LP A-4 (B 4) SMI II A-1 (E A1) SMI II B-3 (E B1) SMI 33 (E 33) Port Barre B-114

142

LMM L&M L&M LMM LMM LMM LMM LMM W, H&W

KCI-H35-10 Unit 2 No. 2 Unit 1 No. 6 81 x 14 KCI No. 63 21-20 45-19 86 × 33 66 x 2 62 x 11 24 x 11 43-31 ColeFee 24 Young No. 63 Young No. 63 KCI 1 17-1 Apollo WD-1 Glide 6

3745 198 697 7847 2084 6387 3100 3329 1827 1299 1804 92 279 298 513 406 303

KCI-H35-10 Oil Unit 2 No. 2 Oil Unit 1 No. 6 81X-14 KCI No. 63 21-20 45-19 86X-33 66X-2 62X-11 24X-11 NCL 43-31 Cole-24 Young 63 Young 63 KCL 31 17-1 Apollo WD-1 Glide 6

1742 0 0 4770 3648 4515 1181 1304 676 166 3208 0 0 0 0 0 0

F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B F&B

F&B = FISHERand BOLES(1990); H&W = HANORand WORKMAN(1986); LMM = LANDetal. (1988); L&M = LANDand MACPHERSON(1989); W = WORKMAN(1985). cited above, alkalinity titrations provide an independent check on the upper limit of total C A A s which could be present in these waters. Total organic acids in Lighthouse Point No. 4 (Louisiana Gulf Coast well 15 of MAcGOWAN and SURDAMand well B-4 of LAND et HI., 1988), as measured by MACPHERSON (1989) by titration, are 1090 mg/1 as acetic acid. In contrast, M a c G o w a n and Surdam report an acetate content of 3720 ppm and a total C A A concentration of 4430 ppm. A computer-simulated titration using P H R E E Q E (PARKHURST et al., 1985) of a sodium acetate-bicarbonate solution containing 1090 mg/1 acetate and 250 mg/1 bicarbonate almost exactly duplicates the shape of the actual alkalinity titration curve for this water (Fig. 2). In contrast, a c o m p u t e r simulation using 4430 mg/1 acetate and 250 mg/1 bicarbonate, intended to model the high C A A content reported by MAcGOWANand SURDAM,results in a drastically different and unreasonable fit (Fig. 2). Similar simulation results (not shown) were obtained for E u g e n e Island 313-B-19, for which MAcGOWAN and SURDAM report 5690 ppm C A A s and LAND and MACPHERSON report 1608 mg/1 organic alkalinity as acetate. The a g r e e m e n t between organic acid con-

centrations determined chromatographically and those estimated from alkalinity titrations is generally quite good, and both values are c o m m o n l y lower than values reported by MAcGOWAN and SURDAM.

SAN JOAQUIN BASIN

The h,I_AcGOWAN and SURDAM values for total C A A s in San Joaquin Basin formation waters are, with the exception of two samples, significantly higher than the concentrations reported by FISHER and BOLES (1990) for waters from these same wells (Table 1). As is the case for the Louisiana Gulf Coast formation waters, many of the MAcGOWAN and SURDAM total C A A concentrations for San Joaquin samples exceed the total titration alkalinities for these same waters (FISHER and BOLES, 1990).

DISCUSSION

Because of lack of adequate documentation of the samples analyzed by MAcGOWAN and SORDAM we

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F~6.1. Cross plot of the concentrations of total monofunctional carboxylic acid anions in San Joaquin and Louisiana Gulf Coast formation waters published by MACGOWANand SURDAM(1990) with previously published analytical data for the same wells. LM&M and L&M refer to values for total organic acids of LAND et al. (1988) and LAND and MACPHERSON (1989); H&W and F&B refer to total mono CAAs of HANOR and WORKMAN(1986) and FISHERand BOLES (1990). With the exception of two samples, and MAcGOWAN and SURDAMvalues are significantly higher than previously published analyses.

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10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 ml Titrant(0.01639N H2SO4) FIG. 2. Comparison of the alkalinity titration curve for sample B-4 of LAND et al. (1988), which is from the same well as Louisiana Gulf Coast sample 15 of MAcGOwAN and SURDAM (1990), with a computer-simulated titration of a sodium acetate-bicarbonate solution containing 1090 mg/1 CAAs as acetate and 250 mg/1 bicarbonate, values reported by LAND et al. (1988). A computer simulation using 4430 mg/I acetate and 250 mg/l bicarbonate, intended to simulate the high CAA content reported by MAcGOWAN and SURDAM, produces an unreasonable fit.

have n o way of assuming here which of t h e i r analyses, if any, are of splits of samples previously analyzed by o t h e r s a n d which are of samples from the same wells collected at some unspecified o t h e r time or date. W e also have n o m e a n s of identifying w h a t aspects of t h e

307

MAcGOWAN a n d SURDAM field p r o c e d u r e s a n d / o r l a b o r a t o r y t e c h n i q u e s h a v e led to generally excess values. While some v a r i a t i o n in p r o d u c e d w a t e r compositions can occur o v e r a p e r i o d of time, this is not a sufficient r e a s o n to account for the consistently high values for C A A s r e p o r t e d by MAcGOWAN a n d SURDAM. It is r e a s o n a b l e to conclude o n the basis of c o m p a r i s o n s which can be m a d e with previously p u b l i s h e d work, h o w e v e r , t h a t the M a c G o w a n a n d SURDAM data do not accurately reflect c o n c e n t r a t i o n levels of C A A s p r e s e n t in San J o a q u i n Basin a n d Louisiana G u l f Coast f o r m a t i o n waters. While we agree with t h e s e a u t h o r s t h a t " . . . the ability to m o d e l the c o n c e n t r a t i o n a n d distribution of C A A S t h r o u g h space a n d t i m e , " is i m p o r t a n t , their o w n analyses do not provide a reliable basis for testing the hypothesis that C A A s are a significant c o m p o n e n t of a " . . . viable, holistic m e c h a n i s m . . . " to explain clastic diagenesis. Editorial handling: Y. K. Kharaka.

REFERENCES

APHA (1976) Standard Methods for the Examination of Water and Wastewater, 14th edition. Washington, D.C., American Public Health Association, Washington, D.C. FISHER J. B. and BOLESJ. R. (1990) Water-rock interaction in Tertiary sandstones, San Joaquin basin, California, U.S.A.: Diagenetic controls on water composition. Chem. Geol. 82, 83-101. HANOR J. S. and WORKMAN A. L. (1986) Distribution of dissolved volatile fatty acids in some Louisiana oil field brines. Appl. Geochem. 1, 37-46. LAND L. S. and MACPHERSONG. L. (1989) Geochemistry of formation water, Plio-Pleistocene reservoirs, Offshore Louisiana. Trans. Gulf Coast Assoc. Geol. Soc. 39,421430. LAND L. S., MACPHERSONG. L. and MACKL. E. (1988) The geochemistry of saline formation waters, Miocene, offshore Louisiana. Trans. Gulf Coast Assoc. Geol. Soc. 38, 503-511. LIco M. S., KHARAKHA Y. K., CAROTnERS W. M. and WRICHT V. A. (1982) Methods for collection and analysis of geopressured, geothermal, and oil field waters. U.S. Geol. Surv. Water Supply Paper 2194. MAeGOWAN D. B. and SURDAM R. C. (1990) Carboxylic acid anions in formation waters, San Joaquin Basin and Louisiana Gulf Coast, U.S.A.--Implications for clastic diagenesis. Appl. Geochem. 5,687-701. MACPHERSON G. L. (1989) Lithium, boron, and barium in formation waters and sediments, northwestern Gulf of Mexico sedimentary basin. Ph.D Dissertation, University of Texas at Austin. PARKHURSTD. t . , THORSTENSOND. C. and PLUMMERL. N. (1985) P H R E E Q E - - A computer program for geochemical calculations. U.S. Geol. Surv. Water Res. Invest. 8096. WORKMANA. L. (1985) Analysis of fatty acids in Louisiana oil-field brines. M.S. Thesis, Louisiana State University, Baton Rouge.