METHOD OF USING BIOMOLECULES TO PREDICT SOURING IN OILFIELD SYSTEMS

Abstract

The present invention is a method for the early detection or prediction of souring of aqueous systems by detecting a population of lipid and organic acids and the treatment of such systems.

Claims

1. A method for the early detection of souring comprising: i) preparing an aqueous sample comprising microorganisms; and, ii) analyzing the sample for the presence of lipids and organic acids selected from the group consisting of iso- and anteiso-methyl branched fatty acids containing 13, 15, or 17 carbons, iso-methyl branched fatty acids containing 18 carbons, 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid; wherein the presence of the combination of one or more of 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid at a concentration greater than or equal to 0.8% combined with four or more lipids indicates the presence of souring.

2. The method of claim 1 wherein each of 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid are combined in the sample and the total concentration of the combination is present at a concentration greater than or equal to 0.8%.

3. The method of claim 1 wherein each of 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid are combined in the sample and each of 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid is present at a concentration greater than or equal to 0.8%.

4. The method according to claim 1, wherein the analyzing step comprises a quantitative or qualitative detection of lipids and organic acids.

5. The method according to claim 1, further comprising detecting five of the lipids.

6. The method according to claim 1, further comprising detecting at least six of the lipids.

7. The method according to claim 1, further comprising detecting all seven of the lipids.

8. The method according to claim 1, wherein the analyzing comprises contacting the sample with a reagent composition or test device that enables qualitative or quantitative detection of lipids and organic acids that are characteristic of said compounds.

9. A method for treating a souring aqueous system comprising: i.) detecting souring according to the method of claim 1; and ii.) applying a biocide, hydrogen sulfide scavenger, or combination thereof.

Description

EXAMPLES

Extraction of Organic Acids

[0015] The samples collected for metabolite analysis consisted of 1 L of water, either taken directly from a tank or separated from the oil. After which, they were alkalized using 50 ml of a saturated NaHCO.sub.3-solution. The organic acids were then extracted three times with 300 ml of chloroform. Subsequently, the aqueous phase was acidified using 5 ml HCl (12 M) and extracted with 300 ml of ethyl acetate. The organic phases were combined, dried over sodium sulfate and evaporated to dryness under a stream of nitrogen. The extract was re-dissolved in 1 ml of diethyl ether for derivatization. Phenylsuccinic acid (100 g) was added as an internal standard, to allow quantification of the detected acids.

Derivatization

[0016] Half of the organic acid extract was used for methylation with diazomethane and analyzed by GC-MS. The other half was taken to derivatize succinic acids to succinimides using (R)-1-phenylethanamine. For a detailed description of the latter derivatization technique, see Jarling et al. (2015). Jarling, R., Khner, S., Basilio Janke, E., Gruner, A., Drozdowska, M., Golding, B. T., Rabus, R., Wilkes, H., 2015. Versatile transformation of hydrocarbons in anaerobic bacteria: substrate ranges and regio- and stereo-chemistry of activation reactions. Frontiers in Microbiology, 6:880.

Medium-Pressure Liquid Chromatography

[0017] Medium-pressure liquid chromatography was performed according to the procedure described by Radke et al. (1980). Radke, M., Willsch, H., Welte, D. H., 1980. Preparative hydrocarbon group type determination by automated medium pressure liquid chromatography. Analytical Chemistry 51, 406-411. The crude oil sample (30 mg) was diluted in 600 l n-hexane and injected. Hetero compounds were retained on the pre-column. The aliphatic hydrocarbons were eluted with 40 ml n-hexane (flow rate: 8 ml/min). After an inversion of the flow direction, the aromatic hydrocarbons were eluted with 72 ml n-hexane (flow rate: 8 ml/min) from the main column. All fractions were vaporized and dried under a stream of nitrogen.

GC-MS Analysis

[0018] The gas chromatographic-mass spectrometric (GC-MS) analysis was performed on a gas chromatograph equipped with a fused silica capillary column (50 m length; 0.22 mm inner diameter; 0.25 m film thickness, SGE Analytical Science). A sample volume of 1 l was injected into the Programmed Temperature Vaporization (PTV) injector in splitless mode. The injector was programmed with a heating rate of 10 C./s from 50 C. to 300 C. Helium was used as a carrier gas with a flow rate of 1 ml/min. The GC oven was programmed to ramp from 50 C. (1 min hold time) to 310 C. (held for 30 min) with a heating rate of 3 C./min. The ion source temperature of the mass spectrometer was 230 C. and the ionization was performed by EI (electron impact) with an ionization energy of 70 eV. Mass spectra were recorded over a range of m/z 50-600 (derivatized organic acids of water extracts) and m/z 50-310 (aromatic hydrocarbon fraction) at a rate of 2.5 scans/s.

Phospholipid Analysis

[0019] Oil-water mixtures from active producing wells were sampled using 10 L jerry cans and allowed to separate into phases before further processing. Water from topside facilities (separator tanks, water buffer tanks, and injectors) was filled into 5 L sterilized glass bottles.

Extraction of Intact Phospholipids

[0020] Directly after sampling, 2 L of each water sample was filtered to collect and concentrate microbial cells using a Satorius filtration system, with glassfibre prefilters in combination 0.2 m, I.D.: 50 mm filters. The filters containing the microbial cells were treated using a modification of the extraction method described by Bligh and Dyer (1959). Bligh E G, Dyer W J (1959) A rapid method of total lipid extraction and purification. Can J Biochem Phys 37: 911-917.

[0021] The filters containing the cells were saturated three times with a solvent mixture of methanol-dichloromethane-ammonium acetate buffer (10 mmol*L1), 2:1:0.8 (v/v) in a beaker and sonicated for 10 min. The extracts were combined by transfer to a separation funnel and spiked with 50 g deuterated [D31]-palmitoyl lysophosphatidylcholine (LPC) as an internal standard. The composition of the solvent was changed to about 1:1:0.9 (v/v) by adding dichloromethane and ammonium acetate buffer to allow phase separation. After separation of the organic phase, the water phase was extracted twice with 20 ml dichloromethane. The organic phases were combined, concentrated using a TurboVap and dried under a stream of nitrogen.

[0022] The extract was dissolved in 1 ml of chloroform-methanol, 9:1 (v/v) and applied to a silica gel column (1 g silica gel 63-200 m) and a florisil column used in sequence and eluted in the following order: 20 ml chloroform (neutral polar fraction), 50 ml methyl formate with 0.025% pure acetic acid (free fatty acid fraction), 20 mL acetone (glycolipid fraction) and 25 ml methanol (phospholipid fraction, only the silica column) and 25 ml of methanol-water, 6:4 (v/v) (highly polar fraction). The latter step contributes to significant improvement in the recovery of highly polar phospholipids from the silica column (Zink K, 2004). Zink K-G, Mangelsdorf K (2004) Efficient and rapid method for extraction of intact phospholipids from sediments combined with molecular structure elucidation using LC-ESI-MS-MS analysis. Anal Bioanal Chem 380: 798-812.

[0023] The highly polar fraction was collected and mixed with dichloromethane and water to achieve a methanol-dichloromethane-water ratio of 1:1:09 (v/v). After separation of the organic phase, the water phase was extracted twice with 20 mL dichloromethane. The organic phases obtained from the highly polar fraction were combined with the phospholipid fraction, evaporated and dried under a nitrogen stream.

Phospholipid Fatty Acid Analysis

[0024] Half of the phospholipid-containing extract was used for trans-esterification to obtain PLFAs from the intact phospholipids using a method described in the literature (Mller et al., 1990). Mller K-D, Husmann H, Nalik H P (1990) A new and rapid method for the assay of bacterial fatty acids using high resolution capillary gas chromatography and trimethylsulfonium hydroxide. Zbl Bakt 274: 174-182.

[0025] A 500 l addition of Trimethylsulfonium hydroxide was combined with the extract and the sealed vial was kept at 70 C. for 2 h. A GC-MS analysis was performed using a system equipped with a BPX5 fused silica capillary column (50 m length; 0.22 mm inner diameter; 0.25 m film thickness). A sample volume of 1 l was injected into the Programmed Temperature Vaporization (PTV) injector operated in splitless mode. The injector was programmed to ramp from 50 C. to 300 C. (10 min hold time) at a heating rate of 10 C./s. Helium was used as the carrier gas at a flow rate of 1 ml/min. The GC temperature program commenced at 50 C. (held for 1 min) followed by a temperature increase at a rate of 3 C./min to 310 C. (held for 30 min). The ion source temperature of the mass spectrometer was 230 C. The ionization was conducted by electron impact (EI) using an ionization energy of 70 eV. Mass spectra were recorded over a range of m/z 50-600 at a rate of 2.5 scans/s. PLFAs were identified by comparison of the mass spectra and retention times of their methyl esters to reference standards.

Methods of Early Detection of, and/or Prediction of, Souring

[0026] The methods and compositions described herein are based upon the discovery that the presence of certain lipids and organic acids of microbial origin can be used as accurate predictors of pending or ongoing souring-related processes. The methods and compositions described herein enable early detection of souring through detection of these specified compounds and permit treatment programs to be designed and implemented for eliminating or minimizing microbial activities to prevent or control souring.

[0027] The environments of soured wells, wells in the early process of souring, and non-soured wells can be discriminated from each other based on distinct differences in the presence of indicator lipids and organics acids. Based on geochemical ecosystem parameters and if the wells are suffering from an issue that correlates to the presence and activities of microbes, their environments become more discriminative from each other and results in differences in concentration or lipids and organic acids in wellbore fluids found in the waters from these environments. Qualitative and/or quantitative detection of iso- and anteiso-methyl branched fatty acids containing 13, 15, 17 carbons, or iso-methyl branched fatty acids containing 18 carbons, as well as the organic acids 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, and 3-ethylbenzoic acid may be used to detect wells or tanks that will sour.

[0028] The above described methods may be used on-site at oil or gas processing sites.

[0029] One of skill in the art may construct a number of suitable reagent compositions for use in the methods described herein given the teachings of this specification.

[0030] In order to further understand the above-described invention and to demonstrate how the method may be carried out in practice, certain embodiments will now be described with reference to the accompanying drawings above and the examples described below. The following examples are provided for illustration and do not limit the disclosure or scope of the claims and specification.

Example 1

[0031] The samples used for this invention were obtained from a series of oil reservoirs located in Upper Austria. Three oil fields are classified as hot reservoirs with temperatures between 80-90 C., while one reservoir is stable at around 52 C. due to the shallower depth. Temperatures in topside facilities ranged from 35 to 40 C. Water-oil mixture samples were obtained directly at the well head of the production wells, while the aqueous phase of produced fluids from separator and buffer tanks were sampled.

[0032] In the examples below, the presence of three organic acids at proportions higher than 0.8% with the detection of four to seven lipids can be used to accurately predict the occurrence of souring.

[0033] Specifically, the analysis was performed as follows:

[0034] The samples collected for organic acid analysis consisted of 1 L of water, either taken directly from a tank or separated from the oil. After which, they were alkalized using 50 ml of a saturated NaHCO3-solution. The organic acids were then extracted three times with 300 ml of chloroform. Subsequently, the aqueous phase was acidified using 5 ml HCl (12 M) and extracted with 300 ml of ethyl acetate. The organic phases were combined, dried over sodium sulfate and evaporated to dryness under a stream of nitrogen. The extract was re-dissolved in 1 ml of diethyl ether for derivatization. Phenylsuccinic acid (100 g) was added as an internal standard, to allow quantification of the detected acids.

[0035] Half of the organic acid extract was derivatized by methylation using diazomethane and analyzed by GC-MS. The other half was taken to derivatize succinic acids to succinimides using (R)-1-phenylethanamine. For a detailed description of the latter derivatization technique, see Jarling et al. (2015).

[0036] Medium-pressure liquid chromatography was performed according to the procedure described by Radke et al. (1980). The crude oil sample (30 mg) was diluted in 600 l n-hexane and injected. Hetero compounds were retained on the pre-column. The aliphatic hydrocarbons were eluted with 40 ml n-hexane (flow rate: 8 ml/min). After an inversion of the flow direction, the aromatic hydrocarbons were eluted with 72 ml n-hexane (flow rate: 8 ml/min) from the main column. All fractions were vaporized and dried under a stream of nitrogen.

[0037] The gas chromatographic-mass spectrometric (GC-MS) analysis was performed on a gas chromatograph equipped with a fused silica capillary column (50 m length; 0.22 mm inner diameter; 0.25 m film thickness, SGE Analytical Science). A sample volume of 1 l was injected into the Programmed Temperature Vaporization (PTV) injector in splitless mode. The injector was programmed with a heating rate of 10 C./s from 50 C. to 300 C. Helium was used as a carrier gas with a flow rate of 1 ml/min. The GC oven was programmed to ramp from 50 C. (1 min hold time) to 310 C. (held for 30 min) with a heating rate of 3 C./min. The ion source temperature of the mass spectrometer was 230 C. and the ionization was performed by EI (electron impact) with an ionization energy of 70 eV. Mass spectra were recorded over a range of m/z 50-600 (derivatized organic acids of water extracts) and m/z 50-310 (aromatic hydrocarbon fraction) at a rate of 2.5 scans/s.

[0038] The samples collected for lipid analysis consisted of oil-water mixtures from active producing wells which were sampled using 10 L jerry cans and allowed to separate into phases before further processing. Water from topside facilities (separator tanks, water buffer tanks, and injectors) was filled into 5 L sterilized glass bottles.

[0039] Directly after sampling, 2 L of each water sample was filtered to collect and concentrate microbial cells using a Satorius filtration system, with glassfibre prefilters in combination 0.2 m, I.D.: 50 mm filters. The filters containing the microbial cells were treated using a modification of the extraction method described by Bligh and Dyer (1959) to extract intact phospholipids. The filters containing the cells were saturated three times with a solvent mixture of methanol-dichloromethane-ammonium acetate buffer (10 mmol*L1), 2:1:0.8 (v/v) in a beaker and sonicated for 10 min. The extracts were combined by transfer to a separation funnel and spiked with 50 g deuterated [D31]-palmitoyl lysophosphatidylcholine (LPC) as an internal standard. The composition of the solvent was changed to about 1:1:0.9 (v/v) by adding dichloromethane and ammonium acetate buffer to allow phase separation. After separation of the organic phase, the water phase was extracted twice with 20 ml dichloromethane. The organic phases were combined, concentrated using a TurboVap and dried under a stream of nitrogen.

[0040] The extract was dissolved in 1 ml of chloroform-methanol, 9:1 (v/v) and applied to a silica gel column (1 g silica gel 63-200 m) and a florisil column used in sequence and eluted in the following order: 20 ml chloroform (neutral polar fraction), 50 ml methyl formate with 0.025% pure acetic acid (free fatty acid fraction), 20 mL acetone (glycolipid fraction) and 25 ml methanol (phospholipid fraction, only the silica column) and 25 ml of methanol-water, 6:4 (v/v) (highly polar fraction). The latter step contributes to significant improvement in the recovery of highly polar phospholipids from the silica column (Zink K, 2004). The highly polar fraction was collected and mixed with dichloromethane and water to achieve a methanol-dichloromethane-water ratio of 1:1:09 (v/v). After separation of the organic phase, the water phase was extracted twice with 20 mL dichloromethane. The organic phases obtained from the highly polar fraction were combined with the phospholipid fraction, evaporated and dried under a nitrogen stream.

[0041] Half of the phospholipid-containing extract was used for trans-esterification to obtain PLFAs from the intact phospholipids using a method described in the literature (Mller et al., 1990). A 500 l addition of Trimethylsulfonium hydroxide was combined with the extract and the sealed vial was kept at 70 C. for 2 h. A GC-MS analysis was performed using a system equipped with a BPX5 fused silica capillary column (50 m length; 0.22 mm inner diameter; 0.25 m film thickness). A sample volume of 1 l was injected into the Programmed Temperature Vaporization (PTV) injector operated in splitless mode. The injector was programmed to ramp from 50 C. to 300 C. (10 min hold time) at a heating rate of 10 C./s. Helium was used as the carrier gas at a flow rate of 1 ml/min. The GC temperature program commenced at 50 C. (held for 1 min) followed by a temperature increase at a rate of 3 C./min to 310 C. (held for 30 min). The ion source temperature of the mass spectrometer was 230 C. The ionization was conducted by electron impact (EI) using an ionization energy of 70 eV. Mass spectra were recorded over a range of m/z 50-600 at a rate of 2.5 scans/s. PLFAs were identified by comparison of the mass spectra and retention times of their methyl esters to reference standards.

Example 2

[0042] GC-MS based profiling of lipids and organic acids from over 500 samples from oil fields and topside facilities located in Upper Austria was completed. Three oil wells, from two different oil fields, as well at three tanks and 1 separator were samples over a period of three days, quarterly, for a period of three years. Of these locations, two of the wells, 1 tank, and the separator were sour. Analysis of the lipid and organic acid data revealed that a greater diversity of lipids were present in souring affected systems but dramatically absent in souring-free systems. Based on these findings, it was determined that a combination of lipids and organic acids could be used to detect soured wells, tanks, and separators.

[0043] Additional data were analyzed and summaries are presented in Tables 1 and 2, which demonstrate: When all three organic acids presented are present at 0.8% of the total acid content or greater, in combination with the presence of four or more of the indicted lipids, there is a heightened probability that a souring process is taking place or will take place in the future. Based on samples collected over three years from the four sour sites in the field, analysis shows 100% correlation with souring.

[0044] Tables 1 and 2 list lipid and organic acid data for sour and non-sour wells.

TABLE-US-00001 TABLE 1 Sour Sour Sour Sour Well 1 Well 2 Separator 1 Tank 1 PLFA A B C D E A B C D E A B C D E A B C D E n-C.sub.8-C.sub.20 + + + + + + + + + + + + + + + + + + + + n-C.sub.21-C.sub.24 + + + + + + i-C.sub.13 * + + + + + + + + + + + + i-C.sub.14 + + + + + + + + + + + + + i-C.sub.15 * + + + + + + + + + + + + + + + + + + + i-C.sub.16 + + + + + + + + + + + + + + + + + + + i-C.sub.17 * + + + + + + + + + + + + + + + + + i-C.sub.18 * + + + + + + + + + + + i-C.sub.19 + + ai-C.sub.13 * + + + + + + + ai-C.sub.14 + + + + + + ai-C.sub.15 * + + + + + + + + + + + + + + + + + ai-C.sub.16 + + + + + + + + + + + + + + + ai-C.sub.17 * + + + + + + + + + + + + + + + + + + + ai-C.sub.18 + + ai-C.sub.19 + + 10-Me16:0 + + + + + 16:17cis + + + + + + + + + + + + + + 16:17trans + + + + 16:19 + + + + + + 17:16 + + + + + 17:1cyclo + + + + + + 18:17cis + + + + + + + + + + + + + + + + 18:17trans + + + + + 18:19 + + + + + + + + + + + + + + + + + + Non-sour Non-sour Non-Sour Tank 2 Tank 3 Well 3 PLFA A B C D E A B C D E A B C D E n-C.sub.8-C.sub.20 + + + + + + + + + + + + + + + n-C.sub.21-C.sub.24 + + i-C.sub.13 * i-C.sub.14 i-C.sub.15 * i-C.sub.16 i-C.sub.17 * i-C.sub.18 * i-C.sub.19 ai-C.sub.13 * ai-C.sub.14 ai-C.sub.15 * ai-C.sub.16 + + + + ai-C.sub.17 * ai-C.sub.18 ai-C.sub.19 10-Me16:0 16:17cis 16:17trans 16:19 17:16 17:1cyclo 18:17cis + 18:17trans + 18:19 + + + + Table outlining the detected lipids in the different samples. The (+) indicates that the lipid was detected in the sample, the lipids with an asterisk (*) can be used as indicators of souring. The letters below the site names indicate samples collected over time.

TABLE-US-00002 TABLE 2 Sour Sour Sour Sour Non-sour Non-sour Non-sour % of % of % of % of % of % of % of Organic Acids Well 1 Total Well 2 Total Sep. 1 Total Tank 1 Total Tank 2 Total Tank 3 Total Well 3 Total Benzoic acid 8.84E+07 5.19% 1.22E+06 0.70% 3.98E+07 5.34% 1.18E+08 18.14% 1.07E+05 28.93% 5.32E+05 28.35% 1.52E+07 30.82% Phenylacetic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 7.01E+04 3.74% 0.00E+00 0.00% 2-Methylbenzoic acid 2.45E+07 1.44% 1.76E+05 0.10% 1.17E+07 1.57% 1.37E+07 2.12% 0.00E+00 0.00% 3.22E+04 1.72% 0.00E+00 0.00% 3-Methylbenzoic acid 1.71E+08 10.03% 1.56E+06 0.89% 1.27E+08 17.04% 1.52E+08 23.45% 8.17E+04 22.17% 0.00E+00 0.00% 6.53E+06 13.27% 2-Phenylpropionic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 2.52E+05 13.42% 0.00E+00 0.00% 4-Methylbenzoic acid 5.78E+07 3.39% 5.56E+05 0.32% 4.06E+07 5.44% 4.72E+07 7.27% 0.00E+00 0.00% 3.07E+04 1.64% 1.54E+06 3.14% 2-Ethylbenzoic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% o-Tolylacetic acid 5.54E+06 0.33% 0.00E+00 0.00% 0.00E+00 0.00% 6.20E+06 0.96% 0.00E+00 0.00% 2.87E+04 1.53% 0.00E+00 0.00% m-Tolylacetic acid 2.47E+06 0.15% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 3-Phenylpropionic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 3.76E+04 2.00% 0.00E+00 0.00% p-Tolylacetic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 2,5-Dimethylbenzoic acid 6.60E+06 0.39% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 2,4-Dimethylbenzoic acid 3.36E+06 0.20% 1.29E+05 0.07% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 3-Ethylbenzoic acid * 1.50E+07 0.88% 1.60E+07 9.13% 1.14E+07 1.52% 1.21E+07 1.86% 0.00E+00 0.00% 0.00E+00 0.00% 9.21E+05 1.87% 2,3-Dimethylbenzoic acid 1.06E+07 0.62% 9.98E+07 56.97% 9.04E+06 1.21% 8.94E+06 1.38% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 3,5-Dimethylbenzoic acid * 1.45E+07 0.85% 4.02E+07 22.96% 3.35E+07 4.48% 3.36E+07 5.19% 0.00E+00 0.00% 5.90E+04 3.15% 0.00E+00 0.00% 3,4-Dimethylbenzoic acid * 7.78E+07 4.56% 1.51E+07 8.64% 4.79E+07 6.42% 4.75E+07 7.33% 5.29E+04 14.34% 0.00E+00 0.00% 0.00E+00 0.00% 1-Naphthoic acid 7.31E+06 0.43% 5.27E+04 0.03% 1.04E+07 1.39% 9.36E+06 1.44% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 2-Naphthoic acid 3.97E+07 2.33% 3.23E+05 0.18% 4.63E+07 6.21% 4.48E+07 6.91% 0.00E+00 0.00% 0.00E+00 0.00% 8.55E+05 1.74% Cyclohexanecarboxylic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 4.80E+05 25.57% 0.00E+00 0.00% 2-Methylcyclohexanecarboxylic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 4.46E+04 2.38% 0.00E+00 0.00% 3-Methylcyclohexanecarboxylic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 2.05E+05 10.91% 0.00E+00 0.00% 4-Methylcyclohexanecarboxylic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 5.50E+04 2.93% 0.00E+00 0.00% Cyclohexaneacetic acid 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 4.99E+04 2.66% 0.00E+00 0.00% Percent Percent Percent Percent Percent Percent Percent of of of of of of of Organic Acids Well 1 Total Well 2 Total Sep. 1 Total Tank 1 Total Tank 2 Total Tank 3 Total Well 3 Total n-C4 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C6 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C8 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C9 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C10 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C11 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C12 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C14 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 4.31E+06 0.66% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C15 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-C16 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 6.45E+06 1.00% 7.69E+04 20.85% 0.00E+00 0.00% 0.00E+00 0.00% n-C18 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 5.82E+06 0.90% 5.05E+04 13.71% 0.00E+00 0.00% 0.00E+00 0.00% Methylsuccinic acid 8.81E+08 51.70% 0.00E+00 0.00% 2.45E+08 32.87% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% Dimethylsuccinic acid 1.90E+08 11.13% 0.00E+00 0.00% 8.74E+07 11.72% 1.00E+08 15.46% 0.00E+00 0.00% 0.00E+00 0.00% 1.51E+07 30.60% Ethylsuccinic acid 8.44E+07 4.95% 0.00E+00 0.00% 3.57E+07 4.79% 3.84E+07 5.93% 0.00E+00 0.00% 0.00E+00 0.00% 8.27E+06 16.80% Isopropylsuccinic acid 8.58E+06 0.50% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% n-Propylsuccinc acid 1.59E+07 0.93% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 0.00E+00 0.00% 8.70E+05 1.77% Table outlining the detected organic acids in the different samples. The numbers are peak areas of each organic acid in the sample, and the percentages indicate percent abundances for each acid in relation to total acids for that sample. The names with an asterisk (*) indicate the organic acids that can be used as indicators, when present at abundances of 0.8% or more in the sample