### Open-file Report No. 2 

# BENZENE IN WATER PRODUCED FROM KERN COUNTY OIL FIELDS CONTAINING FRESHWATER

**~** DEPARrMENT OF

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**~** CONSERVATION



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RESOURCES AGENCY STATE OF CALIFORNIA, DEPARTMENT OFCONSERVATION DOUGLAS P. WHEELER, Secretary PETEWILSON, Governor MICHAELF. BYRNE, Director

# BENZENE IN WATER PRODUCED FROM KERN COUNTY OILFIELDS CONTAINING FRESHWATER

by 

# MarkT. 

# Gamache Energy and Mineral Resources Engineer Division ofOil, Gas, and Geothermal Resources

Sacramento 1993 CaliforniaDepartmentofConservation Division ofOil, Gas, & Geothermal Resources William F. Guerard, Jr., State Oil and Gas Supervisor

# CONTENTS Summary............................................................................................ 

## 1 Introduction ....................................................................................... 1 Procedure ...........................................................................................2 Location ofsamples ............................................................................ 3 Data................................................................................................... 3 Data analysis ....................................................................................... 3 Statistical analysis ................................................................................4 Conclusion ......................................................................................... 5 Selected References .............................................................................. 6 

## FIGURES Map 1. Location ofoil fields sampled ................................................... 7 Table 1. Location and related information for benzene samples

........ 8-11 Figure 

## 1. Scatter diagram- 0

### API gravity versus benzene ....................... 

## 12 Figure 2. Scatter diagram

- formation depth ve:rsus benzene
................. 13

iii

# BENZENE IN WATER PRODUCED FROM I<ERN COUNTY OIL FIELDS CONTAINING FRESH WATER by Mark T. Gamache



## SUMMARY During the summer of 1992, a projectwas begun to sample produced water in Kern Countyoil fields that contain underground freshwater aquifers. The project was undertaken to make a regional comparison among benzene levels in such fields in an effort to assess the possibility ofgroundwater degradation. Fifty-eight samples were obtained from producedwater, which came from single zones when possible. Tankfarms were the preferred choice for taking the water samples when the producedwater was notcommingled with water from different zones. A tank sample is a composite sample from several wells and, therefore, more representative ofa zone. Statistical analysis demonstrated a direct correlation between benzene amounts and theAPI gravity ofcrude oil and an indirect correlation between benzene amounts and formation depth. Linear regression ofthe data produced a best-fit line on a scatter diagram and allowed prediction ofthe amountofbenzene in producedwater when the API gravity ofthe oil or the formation depth are known. Several othervariables, includingwater cut, contribute to an unexplained error in the linear regression. Although oilfield fluids might contain significant levels ofbenzene, a hazard exists onlywith exposure to humans orthe environment. Ifa permitted injection zone is exempt perUnited States Environmental ProtectionAgency (EPA) criteria and does not include



### BENZENEINWATER an underground source ofdrinkingwater, no problem should occur ifsome benzene from producedwater enters the injection zone along with injected water. Onthe otherhand, the practice ofdisposing of produced water in sumps should be questioned when the area contains underground freshwater aquifers, and the produced water has high benzene levels. The Regional Water QualityControl Board is phasingout sumps iln freshwater areas. Thebenzene data generated during this study suggest benzene levels are generally low in producedwater, falling below the 0.5 mg/LToxicity Characteristic Leaching Procedure regulatory level in 40 ofthe 58 samples collected. 

## INTRODUCTION
From April throughJune 1992, a projectwas undertaken to sample produced water in Kern Countyoil fields to measure the amountofbenzene invarious formation waters. Oil fields with underground freshwater aquifers were targeted for the studyto assess the possible degradation ofunderground sources of drinkingwater bybenzene. Such oil fields generallylie east ofInterstate 5 (I-5) in Kern County, although a few, such as Landslide, Yowlumne, andNorth Coles Levee, are west ofl-5 

### (see Map 1). Wheeler Ridge oil field was included in the studybecause itis near potential residential areas, and itis uncertain whether the field has a shallow, freshwater zone.Benzene is a volatile, aromatic, organic molecule found in the light fraction ofcrude oils (Haun, 1977). The solubility ofbenzene is 0.180 g/100 ml water at 25°C. The specific gravity is 0.87865 and the vapor pressure is 75 torr at 20°C (Sax and Lewis, 1989). The principal route ofexposure to benzene by humans is from inhalingvapor or by skin absorption. Benzene is moderately toxic by ingestion. The primarymanifestation ofdisease from benzene exposure is acute, central nervous system depression, leukemia, aplastic anemia, and dermatitis ifthe skin is involved (Levy and Wegman, 1988).
Benzene is considered to be a confirmed human carcinogen by the American Conference ofGovernment Industrial Hygienists (ACGIH). 

### Ithas a threshold limitvalue (TLV:TWA) guideline of0.1 parts per million (ppm).1 The Occupational Safety and Health Administration (OSHA) permissible exposure limits (PEL:TW A) are 1.0 ppm. On March 

### 3, 1990, the United States Environmental ProtectionAgency (EPA) added benzene to the list of"EP Characteristic" wastes. The Toxicity Characteristic Leaching Procedure test (TCLP) regulatory level for benzene in hazardous waste is 0.5 mg/L. 2
Due to intermingling, producedwater can contain some benzene derived from crude oil. Presently, producedwaterfrom oilfield operations is exempt from EPA regulatoryrequirements for hazardous wastes. Also, producedwateris disposed ofbyinjection into Class II wells (i.e., disposal and enhanced oil recovery wells) or through placement in percolation sumps where some is lost through evaporation. Some produced water in the study area is fresh enough to serve as a source ofdrinkingwater and is added to the Beardsley Canal near Kern River. 

# PROCEDURE Fifty-eight samples ofproduced waterwere analyzed

1This change from 10 ppm and suspected human carcinogen was proposed by theACGIH in 1990, then published in theThreshold Limit Values and Biological Exposure Indices 1990-1991 booklet.

2California Department ofHealth Services, 1990. Toxicity Characteristic Leaching Procedure (TCLP)--A Guide for California Generators and Handlers ofHazardous Wastes, table 1, p. 6.


### 2 for benzene. Samplingwas targeted on produced water originating from a single zone or formation. Occasionally, a sample ofcommingled produced waterwas taken when individual zone samples were unavailable or the sample had special value. Since the project's main purpose was to compare benzene levels from different formations, the samplingplan was regional in scope. Intensive samplingofeach formation to obtain statistically significant average benzene levels on the local level was neither a part ofnor the purpose ofthe study.
Some produced-water samples were obtained from tank farms and some from producingwells where the oilwas decanted (Photos 1 and 2). Tankfarms were the preferred choice when the producedwaterwas not commingled. Althoughprocessing oil andwater in

Photograph 1. A typical tank containingwaste water and crude oil that was sampled. The oil blanket on top ofthe produced water may prevent benzene in the water from volatilizing.

Photograph 2. Water from the tankwas sampled by using the lowest access line. The produced water was allowed to run for a few minutes to clear the line ofresidue oil before obtaining a sample.

DIVISIONOFOIL, GAS, & GEOTHERMALRESOURCEStank farms may decrease the benzene quantity in produced water; still, a tank sample represents a composite sample from several wells and, therefore, more representative ofthe formation. Tanks also contain the final waste product that maybe injected into a water-disposal well orplaced in a sump. 

### Sampling methodology
Water samples were placed in two, 40-milliliter glass vials and capped with teflon seal lids. Twohundred microliters of 1: 1 hydrochloric acid was added to each sample as a preservative. The vials were filled to the top, with no head space. After the samples were obtained, theywere cooled to 4°C in the field using "blue ice" and kept in an ice chest. The purpose ofthe acid andrefrigeration was to prevent bacterial growth and benzene degradation. The elimination ofhead space reduced the ability ofbenzene to volatilize outof solution. A traveling blankwas also labelled and accompanied each sample as a negative control. The samples were collected according to the directions ofa state-accredited laboratory and analyzed bythe same laboratory using EPA-approved testing methods. Since the samples were liquid, the sample results can be comparedwith the TCLP regulatory level of0.5 mg/L 

### (= 0.5 ppm) for hazardous waste. 

### Location of samples
The oil fields from which samples were taken are shown onMap 1. Thenumberin each circle refers to the number ofsamples taken from the field. For example, a single sample from Landslide oil field is shown in T. 11N, R. 21W., SBB&M. Information on each sample is given in Table 1.


### Data
The sample datainTable 1 

### (beginning on page 8) are grouped first byzone, which is the source ofthe producedwater, and secondly by oil field and area. Theyoungest and shallowest source zones are grouped at the top, descending into older and deeper zones near

3Formation depths and

### API gravity ofzones are reprinted from California OilandGas Fields. Central California. Volume I.


### BENZENEINWATER the bottom. Note that the Stevens zone is not the oldest zone, but it is the deepest zone sampled.
Ifthe benzene found in produced water is derived from the lighter fraction ofcrude oil, then there should be some correlation with theAPI gravity and the depth of the zone. Therefore, the average API gravity, average zone dc:!pth, and area location were added for comparative purposes.3 Thebenzene values were reported in micrograms per liter. This value was divided by 1,000 to convert it to milligrams per liter (equal to ppm). The intended injection zone for the produced water is shown in the final column. 

### Data analysis
The Kern River zone in Kern River oil field has benzene values below 0.01 ppm for all samples tested. These values were expected, given the low oil gravity and the shallow depths ofthe Kern River zone. The Etchegoin and Chanaczones inEdison oil field and theJewett/Pyramid 

### HillN edder zones in Round Mountain and Mount Poso oil fields also produced comparatively low-gravity oil and waters with low benzene values from shallow-to-medium depths.
The N.lain Area in Fruitvale oil field produces oil from several zones in the following depth order (shallowest to deejpest): Fairhaven, Mason-Parker, Martin, Kernco, and the Santa Margarita. When possible, separate

**samplc~s** were taken from each. The Martin and Kernco samples show the highest values, approaching 0.2 ppm benzene. The Reserve zone was sampled inTejon. andWheeler Ridge oil fields. TheTejon benzenevalue of0.0066 ppm was the lower ofthe two samples and corresponds to the shallow zone depth (1,810 feet} inthat area. Thehigher value of3.7 ppm from Wheeler Ridge is most likely due to the greater depthofthe zone (5,600 feet) and the increase in oil gravity from 17°API in Tejon to 21 oAPI inWheeler Ridge. Produced water from the Stevens zone was sampled in several different oil fields, includingWest Bellevue, Bellevue, Rosedale, Canal, Canfield Ranch, North Coles Levee, Ten Section, and Paloma. The Stevens zone was also sampled as commingled fluids in Yowlumne and Greeley oil fields. Thevalues ranged from a low of0.019 ppm to a high of 18.0ppm, with



### 3an average of4.82 ppm. The data follow natural groupings of0.019 to 0.45 ppm, 2.0 to 3.7 ppm, 5.1 to 6.6 ppm, and 14.0 to 18.0 ppm. There is some difficulty in correlating this grouping to gravity and depth data. Ifthe gravity ofoil and depth ofthe Stevens zone were noted for each oil well contributing produced water to a tank farm sample, perhaps the correlation would be stronger. Anothervariable is producedwater cut. Forexample, the benzene value of0.019 ppm for sample 27 in Canfield Ranch oil field (East GosfordArea) corresponds to a 58 percentwater cut. Sample 61, with a benzene value of2.5 ppm, was also obtained in Canfield Ranch (South GosfordArea) and corresponds to awater cut of 12percent. Sample 10 (East Gosford Area), with a value of3.4 ppm, corresponds to a water cut of60 percent. Therefore, the correlation of benzene values with water cut is weak. Water cuts produce random error, probablybecause ofthe varied sources ofwater. For example, water maybe from the oil horizons and in contact with the oil, or be derived from water-bearing sands at different horizons from the oil. Also, the water might be from an enhanced oilrecovery project. Othervariables include formation temperatures, gas pressure in the crude oil, quantity ofbenzene in oil, sampling process (surface versus at depth), etc. Some ofthese variables might be identified and quantified in a controlled, local sampling study, butthe individual contribution ofeach variable to the unexplained error ofthe linear regressions calculated in this studyis unknown. 

### Statistical analysis
Multivariate correlation can be used when a variable, like benzene quantity in producedwater, is related to two or more othervariables such as API gravity ofoil orformation depth oforigination. Therelative strength ofcorrelationbetweenvariables canbe comparedbycalculatingthe correlationcoefficient r for eachset of variables. Thevalue ofr indicates

4 

### All statistical analyses in this section were calculated from equations and instructions in McGhee,

## J. W., 1985, Introductory Statistics: West Publishing Co., St. Paul, Minnesota p. 395-444.


### 4 whether a correlation, eitherpositive ornegative, exists between two variables. A positive correlation becomes strongeras r increases from 0 to 1. A negative correlation becomes stronger as r decreases from 0 to -1. The r value was calculated for three variable sets: API gravity ofoil versus benzene quantity inproduced water (x 1,y); formation depth oforigination versus benzene quantity in produced water value (x2,y); and API gravity ofoil versus formation depth (x 1,x2). The r for (x1,y) was 0.77, for (x2,y) 0.63, and for (x 1,x2) 0.87. The values indicate a strongpositive correlation between benzene quantityin producedwater toAPI gravity and formation depth oforigination. Furthermore, there is an interactive effect betweenAPI gravity and formation depth. Correlation between variables was verified statistically by testing for the null hypothesis ofno correlation against the alternate hypothesis ofcorrelation. Ifno correlation existed between the variables ofinterest, then there would be a 0.5 percent chance that a random sampling method collecting 58 samples would produce an r value of0.337orgreater. Since the r values obtained for these sets ofvariables were far above 0.337, the null hypothesis is rejected and the conclusion is that a positive correlation exists.
A linear regression was computed for a scatter diagram ofAPI gravityversus benzene quantity, and a scatter diagram offormation depth versus benzene quantity (Figs. 1 and 2, 

### seepages 12 and 13). The statistical method produces a best-fitting line to the datawith the regression line equation y 

## =bo + b 1x. The equation can be used to predict y values for specific values ofx. The equation for each linear regression is shown on the scatter diagrams.
The square ofr is very important in a statistical study and is called the coefficient ofdetermination (r2 ). This value explains what percentage ofdata is attributed to the variable studied and what is not. 

### An

# rvalue of 0.59 is associated with thevariable set, API gravity versus benzene quantity. This means that 59 percent ofthe samples were explained by the regression line (i.e., they fall within the normal population predicted bythe mean). The other 41 percent are attributed to unexplained error. This suggests that other, additional variables account for benzene quantitybesides API gravity. The r2 value for formation depthversus

DIVISIONOFOIL, GAS, & GEOTHERMALRESOURCESbenzene quantity is 0.40, meaning 40 percent ofthe data are explained by the regression line and 60 percent are due to unexplained error. This factor may be explained by looking at the reason why benzene is in produced water. Ifbenzene is found in the lighter fractions ofcrude oil, itwould be expected that lighter crude would contribute more benzene to producedwater than heavier crude. This causal observation is supported by the strong positive correlation between API gravity oil and benzene quantity in produced water. According to Philippi (1965), the aromatic contents in oil increase strongly with depth and age ofsediments, due to thermal maturation and time. This effect is also supported by the moderately strongpositive correlation in this study between benzene quantity in produced water and formation depth.
Benzene has a stronger correlation to API gravity than to formation depth because benzene is derived from the crude oil rather than from the formation. However, an interactive effect exists between oil and formation depth; therefore, there is an indirect correlation between the formation depth and benzene quantity in produced water. For these reasons, predictions ofbenzene quantity in produced water should be based on the linear regression ofAPI gravity to benzene quantity, rather than to formation depth. However, the formation depth might be used as a secondarycheck, or even as a primary predictor, ifAPI gravity is unknown. 

## CONCLUSION
The data collected in this study represent a regional overview ofbenzene in producedwater from Kern Countyoil fields where underground freshwater aquifers are present. Statistical analyses demonstrate a direct, positive correlation betweenAPI gravity ofoil and benzene in producedwater. 

### An indirect, positive correlation was.also demonstrated between depth of formation and amount ofbenzene in producedwater. Several. othervariables, includingwater cut, contribute



### BENZENEIN WATER to the unexplained error ofthe linear regression. Benzene:: quantities can be predicted iftheAPI gravity ofthe o:il or formation depth oforigination is known and the linear regression equations developed from this study are used. Table 1includes the permitted zone ofinjection for fluids containing benzene. Ifthe permitted zone is

**exemptc~d** by the EPA and doesn't contain an underground source ofdrinkingwater, there should 

### be no problem ifsome benzene from producedwater enters the injection zone. However, the practice ofdisposing ofprodlUced water in sumps should be questioned when the area contains underground freshwater aquifers and the produced water has high benzene levels.

**Producc~d-water** spills, by themselves or in conjunction with oil spills, might require further investigation. Oil-contaminated soil is removed routinely, bioremediated, and used as road mix (or otherwise recycled or disposed of). Ifproducedwater containing a large amountofbenzene is spilled, the soil may become contaminated with benzene. However, the soil can bioremediate itselfnaturally, and the benzene can vaporize::. 

### Itmay be beneficial to calculate a predicted

**benzene~** quantityfor the producedwater when such a spill oc<:urs. Thiswould help to determine whether or not a problem exists. Finally, the EPA is considering a change to its policyof exempting oilfield waste from hazardous waste regulations. Thebenzene data generated from this study indicate: benzene levels are generallylowinproduced water (below the 0.5 ppmTCLP regulatory level in 40 ofthe 

## s;s samples collected). Therefore, these data suggest the appropriate decision would be to retain the exempt status. Such a decision could be based notonly on the llow levels ofbenzene in produced water, butof the fact that a regulatoryprocess is already in place for producc::d-water disposal. This is especially important as more: producedwaterwill be subject to injection for disposal purposes as percolation sumps are phased out in areas ofunderground freshwater aquifers.



### 5

## SELECTED REFERENCES
California Department ofHealth Services, 1990, Toxicity Characteristic Leaching Procedure (TCLP)--A guide for California generators and handlers ofhazardous wastes, 19 p., 1 appendix. California Division ofOil and Gas, 1985, California Oil & Gas Fields, Central California, Vol. 1. California Chamber ofCommerce, 1990, Hazardous waste management, 96p., 10 appendices. Editor's note, 1990, Notice ofintended changes-- benzene: applied occupational environmental hygiene, v. 5,no. 7,p.453-463. Haun,J.D. 1977, Some principles ofpetroleum geology--a review, in subsurface geology--petroleum mining construction, Leroy, 

### L. W. and Leroy D. 

### 0. ed., Fourth Edition: Colorado School ofMines, Golden, Colorado, p. 234-240.

6 Levy, B. S., andWegman, D. H., 1988, Occupational health--recognizing and preventingwork-related disease, second edition: Little, Brown and Company, Boston, p. 575. McGhee,

## J. W., 1985, Introductory statistics: West Publishing Company, St. Paul, Minnesota, p. 395- 444. Philippi, G. T., 1965, On the depth, time, and mechanism ofpetroleum generation: Geochimica et ChosmochimicaActa, v. 29, p. 1021-1049. Sax, I. N., and Lewis, R. J., Sr., 1989, Dangerous properties ofindustrial materials, seventh edition, Vol. II: Van Nostrand Reinhold, NewYork, NewYork, p. 364-365.

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### & Gas Fields, Central California, Volume 1. Circled numbers indicate the number ofsamples taken from each field.


### BENZENEIN WATER 

### 7Table 1. Location and related information for water samples. 

### PRODUCED GRAVITY DEPTH FIELD/AREA SECTION SAMP. BENZENE INJECTION WATER OIL ZONE TWN/RNG NUMB. VALUE ZONE ZONE ( 0

### API) (FEET) (PPM) KERN 10-16 400 KERN RIVER SEC. 31 20 0.0007 CHANAC/SANTA RIVER 28S 28E MARGARITA KERN 10-16 400 KERN RIVER SEC. 5 21 0.0011 CHANAC/SANTA RIVER 29S 28E MARGARITA. KERN 10-16 400 KERN RIVER SEC. 30 30 NONE KERN RIVER RIVER 28S 28E DETECTED KERN 10-16 400 KERN RIVER SEC. 25 31 0.0013 SANTA MARGARITA 

### RIVER 28S 27E KERN 10-16 400 KERN RIVER

. SEC. 6 32 NONE SANTA MARGARITA 

### RIVER 29S 28E DETECTED KERN 10-16 400 KERN RIVER SEC. 34 39 NONE SANTA MARGARITA 

### RIVER 28S 28E· DETECTED KERN 10-16 400 KERN RIVER SEC. 5 53 0.0071 KERN RIVER RIVER 29S 28E ETCHEGOIN 11-14 3500 POSO CREEK/ SEC. 32 40 0.0008 SANTA MARGARITA 

### PREMIER 27S 27E ETCHEGOIN 15 3,500 ROSEDALE RANCH SEC. 35 43 NONE ETCHEGOIN 28S 26E DETECTED KERN 14-22 750 EDISON/MAIN SEC. 14 28 0.0054 SCHIST RIVER-CHANAC 30S 29E CHANAC/ 14-29 750/ EDISON/MAIN SEC. 23 58 0.0005 SCHIST SANTA 400/ 30S 29E MARGARITA/ WICKER/NOZU/ 1,500/3,000/ FREEMAN-JEWETT/ 3,150/ WALKER/SCHIST 2,900/1,200 CHANAC 15 1,070 EDISON/RACE SEC. 27 60 0.0047 SANTA MARGARITA 

### TRACK 29S 29E CHANAC 14 2,290 KERN FRONT SEC. 22 54 NONE ETCHEGOIN 28S 27E DETECTED CHANAC 11-15 2,500 POSO CREEK/ SEC. 8 44 NONE CHANAC PREMIER 28S 28E DETECTED CHANAC 18 3,100 FRUITVALE/ SEC. 15 46 NONE CHANAC MAIN 29S 27E DETECTED CHANAC 18 3,100 FRUITVALE/ SEC. 34 2 0.0038 UPPER KERNCO MAIN 29S. 27E

8 DIVISION OFOIL, GAS, & GEOTHERMALRESOURCESTable 1. (continued). Location and related information for water samples. 

### PRODUCED GRAVITY DEPTH FIELD/AREA SECTION SAMP. BENZENE INJECTION WATER OIL ZONE TWN/RNG NUMB. VALUE ZONE ZONE ( 0

### API) (FEET) (PPM) MASON- 18 3,100 FRUITVALE/ SEC. 21 29 NONE MASON-PARKER PARKER MAIN 29S 27E DETECTED MARTIN 22 3,250 FRUITVALE/ SEC. 22 8 0.19 ETCHEGOIN MAIN 29S 27E KERNCO 15-22 3,600 FRUITVALE/ SEC. 28 3 0.13 MIDDLE KERNCO MAIN 29S 27E KERNCO 15-22 3,600 FRUITVALE/ SEC. 14 22 0.0024 ETCHEGOIN MAIN 29S 27E KERNCO 15-22 2,600 FRUITVALE/ SEC. 22 9 0.0006 ETCHEGOIN MAIN 29S 27E CHANAC/ 18 3,100/ FRUITVALE/ SEC. 27 6 0.0088 MARTINj.KEJ.WCO SANTA 4,500 MAIN 29S 27E MARGARITA SANTA 16 715 DEER CREEK SEC. 27 52 0.0078 SANTAM..ABGARITA 

### MARGARITA 22S 27E SANTA 16 1,550 TEJON/WESTERN SEC. 32 13 NONE FRUITVALE/ MARGARITA 11N 20W DETECTED

**~ ~**  

### RESERVE 17 1,810 TEJON/ SEC. 12 55 0.0066 RESERVE SOUTHEAST 10N 19W RESERVE 21 5,600 WHEELER RIDGE/ SEC. 36 33 3.7 RESERVE WINDGAP 11N 20W OLCESE 14 2,300 ANT HILL SEC. 22 47 NONE OLCESE 29S 29E DETECTED CHANAC/ 13-16 1,070/ EDISON/RACE SEC. 34 48 6.3 RaJND lUNfAlN/ 

### SANTA *41 1,830/ TRACK 29S 29E JEWETT MARGARITA/ NOZU/*JEWETT 3,260/4,570 JEWETT 22 1,750 ROUND MOUNTAIN/ SEC. 20 16 NONE JEWETT/ MAIN 28S 29E DETECTED PYRAMID HILL PYRAMID 18-19 1,500 ROUND MOUNTAIN/ SEC. 7 

### 18 0.017 PYRAMID HILL HILL COFFEE CANYON 28S 29E PYRAMID 16-19 1,500/ ROUND MOUNTAIN/ SEC. 7 

### 56 NONE PYRAMID HILL/ HILL/ COFFEE CANYON 28S 29E DETECTED VEDDER VEDDER 1,650 VEDDER 16 1,390 ROUND MOUNTAIN/ SEC. 1.6 57 0.0012 VEDDER PYRAMID 28S 29E * API gravity is 41 for the Jewett zone.



### BENZENEIN WATER 

### 9Table 1. (continued). Location and related information for water samples. 

### PRODUCED GRAVITY DEPTH FIELD/AREA ·sECTION SAMP. BENZENE INJECTION WATER OIL ZONE TWN/RNG NUMB. 

### VALUE ZONE ZONE ( 0

### API) (FEET) (PPM) VEDDER 13 2,800 ROUND MOUNTAIN/ SEC. 14 17 NONE OLCESE SHARKTOOTH 28S 28E DETECTED VEDDER 15-16 1,750 MOUNT POSO/ SEC. 29 23 0.0017 PYRAMID HILL/ MAIN 26S 28E VEDDER VEDDER 15-16 1,750 MOUNT POSO/ SEC. 9 24 0.0065 PYRAMID HILL/ MAIN 27S 28E VEDDER VEDDER 15-16 1,750 MOUNT POSO/ SEC. 22 25 0.0042 PYRAMID HILL/ MAIN 27S 28E VEDDER VEDDER 15-16 1,500 MOUNT POSO/ SEC. 26 26 NONE VEDDER DORSEY 27S 28E DETECTED VEDDER 15-16 1,500 MOUNT POSO/ SEC. 22 49 NONE VEDDER DORSEY 27S 28E DETECTED VEDDER 15-16 1,500 MOUNT POSO/ SEC. 26 50 NONE VEDDER DORSEY 27S 28E DETECTED VEDDER 16 2,400 MOUNT POSO/ SEC. 20 15 NONE OLCESE DORSEY 27S 28E DETECTED WHARTON/ 23-35 5,500/ MOUNTAIN VIEW/ SEC. 21 59 3.5 CHANAC/ NOZU/ 7,300/ MAIN 31S 29E SANTA MARGARITA 

### OLCESE 7,000 STEVENS/ 34-36 8,300/ GREELEY SEC. 7 42 5.1 ETCHEGOIN OLCESE/ 10,530/ 29S 26E RIO BRAVO 11,300 STEVENS 31 12,190 LANDSLIDE SEC. 24 34 .45 STEVENS 11N 24W ETCHEGOIN 29-34 10,400 YOWLUMNE SEC. 3 35 6.6 STEVENS /STEVENS /11,200 12N 22W ETCHEGOIN 29-34 10,400 YOWLUMNE SEC. 4 36 5.2 STEVENS /STEVENS /11,200 12N 22W STEVENS. 33-35 7,000 BELLEVUE/MAIN SEC. 35 14 2.9 STEVENS 29S 26E STEVENS 28-35 7,800 WEST BELLEVUE SEC. 33 4 2.2 STEVENS 29S 26E STEVENS 28-35. 7,800 WEST BELLEVUE SEC. 32 45 2.1 STEVENS 29S 26E

10 DIVISION OFOIL, GAS, & GEOTHERMALRESOURCESTable 1. (continued). Location and related information for water samples. 

### PRODUCED GRAVITY DEPTH FIELD/AREA SECTION SAMP. BENZENE INJECTION WATER OIL ZONE TWN/RNG NUMB. VALUE ZONE ZONE ( 0

### API) (FEET) (PPM) STEVENS 32 5,800 ROSEDALE/MAIN SEC. 23 41 5.5 ETCHEGOIN 29S 26E STEVENS 32 5,800 ROSEDALE/MAIN SEC. 15 51 2.0 ETCHEGOIN 29S 26E STEVENS 35 8,050 CANAL SEC. 14 11 2.4 ETCHEGOIN 30S 25E STEVENS 33 7,900 CANFIELD RANCH/ SEC. 13 27 0.019 ETCHEGOIN EAST GOSFORD 30S 26E STEVENS 33 7,900 CANFIELD RANCH/ SEC, 19 10 3.4 ETCHEGOIN EAST GOSFORD 30S 27E STEVENS 29-34 7,950 CANFIELD RANCH/ SEC. 26 61 2.5 STEVENS SOUTH GOSFORD 30S 26E STEVENS 33-49 8,000 NORTH COLES SEC. 33 38 5.9 STEVENS LEVEE 30S 25E STEVENS 32-60 7,950 TEN SECTION/ SEC. 24 19 3.7 SAN JOAQUIN/ MAIN 30S 25E ETCHEGOIN STEVENS 32-60 7,950 TEN SECTION/ SEC. 30 5 14.0 SAN JOAQUIN/ MAIN 30S 26E ETCHEGOIN STEVENS 35,..55 10,000 PALOMA/MAIN SEC. 10 37 18.0 ETCHEGOIN 32S 26E

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-I 

### -2 

### LINEAR REGRESSION OF FORMATION DEPTH TO BENZENE QUANTITY IN PRODUCED WATER

y: -0.946 

## + 0.000655 X.

\ 

## ,



# ..

6000 8000 10000 12000 

### FORMATION DEPTH (FEET)

Figure 2. Thebenzene quantity in produced water canbepredicted using the formation depth. When the formation depth is known, that value is substituted for the variable

### x in the slope formula and thebenzene valuey calculated.

BENZENEIN WATER OFR02(4-95-GSR1-2C) 13