T. P.8010

Effect of Flow Rate on Paraffin Accumulation in Plastic, Steel, and Coated Pipe

F. W. JESSEN THE UNIVERSITY OF TEXAS MEMBER AIME AUSTIN, TEX, JAMES N. HOWEll'

INTRODUCTION carbonates of iron, barium, and rosion in wells, and in many in­ Downloaded from http://onepetro.org/trans/article-pdf/213/01/80/2179130/spe-968-g.pdf by guest on 29 September 2021 calcium. stances paraffin deposits have been The accumulation of paraffin The petroleum waxes deposited in greatly reduced. Field observations deposits in tubular goods has been flow strings usually consist of both have indicated that plastic coated recognized as a major production a "hard" and a "soft" wax fraction. pipe not only reduced paraffin ac­ problem since the inception of the pe­ These waxes are largely aliphatic cumulation but in some cases elim­ troleum industry. This problem is not hydrocarbons with smaller amounts inated deposition completely; how­ limited to any particular geograph­ of aromatic and naphthenic com­ ever, data are needed to demonstrate ical area nor is it limited to a specific pounds. Nathan' has classified the the relative effectiveness of plastic type of crude oil.! Generally speak­ hard and soft wax fractions. The materials. ing, "paraffin" deposition pertains to aliphatic hydrocarbons present are the deposition of any predominately those of high molecular weight with DEPOSITION ApPARATUS organic material in flow lines, and high melting points. ReistIe3 pointed The pipe used to determine the possibly even at the sand face, which out that these high molecular weight effect of velocity on rates of deposi­ would hamper the production of oil. compounds first separate from the tion was % - and 2-in. nominal di­ In some fields, a continuous effort is oil due to a sharp decrease in solu­ ameter, and 5 ft in length. Steel, required to remove deposits of paraf­ bility as the melting point increases. butyrate, rigid PVC, kralastic resin­ fin and in order to accomplish this, The identification of the resins and type plastic pipes, epoxy coated pipe, many unique methods have been de­ asphaltic materials rests, at present, PVC lined glass fiber pipe, and alum­ vised. The best solution to this prob­ on an arbitrary solubility procedure. inum pipe were tested. Steel pipe lem, however, is to prevent the for­ Under certain conditions, materials was used as a control. mation of such deposits. One method which are insoluble in pentane Fig. 1 is a schematic diagram of which has been tried in a number of (ASTM D-893) are defined as resins the apparatus showing the relative fields is the use of plastic pipe. and asphalts. Sub grouping of these position of the separate units making The purpose of this investigation is materials is made on decreasing solu­ up the equipment. to compare the relative effectiveness bility in benzene and carbon disul­ In order to facilitate the installa­ of several plastic materials to aid in fide: tion and removal of the test pipes in the reduction or prevention of paraf­ Shock! found some correlation be­ the apparatus, O-ring seals capable of fin accumulations in surface flow tween the solvent response and the sustaining pressures of 50 psi were lines. pentane insoluble content of paraf­ provided at each end. fins; higher pentane insoluble frac­ Test pipes were submerged in a COMPOSITION OF PARAFFIN tions are less soluble in any of the cold water bath maintained at or DEPOSITS commonly used commercral solvents. below room temperature by circulat­ By definition, paraffin deposits are ing water through copper cooling PARAFFIN CONTROL coils packed in ice. A hot water bath those materials which are insoluble METHODS in crude oil at the prevailing pro­ equipped with immersion-type heat­ ducing conditions of temperature and The methods used in oil fields to ers, stirrers, and a thermoregulator pressure. Such deposits"" usually con­ prevent and remove paraffin accumu­ was used to maintain the temperature sist of small particles of petroleum lations can be grouped into four gen­ of the oil prior to introduction into wax intermixed with resins, asphaltic eral classes: (1) operative methods, the piping manifold. The capacity of material, and crude oil. They may (2) physical methods, (3) chemical the oil reservoir was 30 gal. also contain a variety of foreign methods, and ( 4 ) combination of A 33-gaI/min centrifugal pump, materials such as sand, silt, water, any of these. Operative methods at­ capable of producing turbulent flow various metal oxides, sulfates and tempt to prevent the formation of velocities in the test pipes, was used paraffin deposits while the other to circulate the oil through the sys­ Original manuscript received in Society methods are concerned primarily with tem when using % -in. pipe; and a of Petroleum Engineers office Aug. 20. 1957. Revised manuscript received March 11, 1958. the removal of these deposits. 70-gaI/min centrifugal pump was ':'Presently associated with The Shell Oil Plastic coated pipe has been used used in later tests using 2-in. pipe. Co .• New Orleans, La. lReferences given at end of paper. for a number of years to prevent cor- A by-pass arrangement made it pos-

PETROLEUM TRANSACTIONS, AIME SPE 968-G 30 sene-saturated rag and then dried K with a clean, dry cloth. L L DISCUSSION OF RESULTS ""J Rates of deposition were obtained by using kerosene and two refined B L-,-A microcrystalline waxes (Figs. 3 and ~ ~ 4) in order to determine the effects - - of the melting point upon the rate f- A,B,C - Flow Rate Control Valves - - c- of deposition. Greatest deposition at D-Oil Reservoir D D E any velocity for the two systems took E -Hot Water Bath J place in the solution containing the F -Centrifugal Pump G-Motor i paraffin with the lowest melting point. H-Header I At first, this appears contrary to what I I - Thermometer i I ! might be expected since the greatest I J-Test Pipe I K -Manometer i I deposition more likely should take L -Cold Waler Bath I I I! place in the solution containing the I Ii ,I I I I highest melting point paraffin; that is, IoMF II i I I the least soluble. FIG. I-PARAFFIX DEPOSlTIOX ApPARA1'l'S. Although both solutions were pre­ Downloaded from http://onepetro.org/trans/article-pdf/213/01/80/2179130/spe-968-g.pdf by guest on 29 September 2021 pared so as to have the same cloud sible to obtain variations in flow experimental run. Undoubtedly the point of 120° F, there was a marked rates through the piping system and temperature drop at the inner wall difference in the concentration of also provided a means for stirring of the pipes was much greater. paraffin due to the solubilities in the oil in the oil reservoir, thus as­ At the completion of a run, which kerosene. A kerosene solution satu­ suring uniform temperature of the normally required a period of about rated with wax having a melting point oil and complete solution of the three hours, the test pipes were re­ of 200° F contained 0.57 gm/ IOO ml paraffin. moved from the apparatus and the at 120°F, while a solution saturated Pressure differentials across the with wax having a melting point of deposited paraffin (which was rather 0 test sections were measured by means uniform throughout the section) was 186 F contained 2.01 gm/ IOO ml of a manometer and a meter was cleaned from the pipes by pushing a at the same temperature. Upon cool­ used to check the total flow. Fig. 2 tight fitting rubber " squeegee" ing to 110° F, the temperature at shows the arrangement of the piping. through the pipes several times. Nor­ which these runs were made, the solu­ bilities decreased to 0.23 and 0.84 CONTACT ANGLE ApPARATUS mal pentane was used to transfer the paraffin from beakers into standard gm/ lOO ml, respectively, for the 200 Conact angle measurements were ASTM 100-ml centrifuge tubes. An and 186° F melting point waxes. The made using Stegemeier's procedure: excess of pentane was then added to change of solubility from 120 to 110° F results, therefore, in 0.34 CLOUD POINT bring the total volume to 100 m!. The mixture was shaken and centrifuged gm/IOO ml free wax in suspension The cloud point of the crude oils in the solution contaiuing the 200° F was determined using the method at 1,500 rpm for 20 minutes. The solid separated was recorded as the melting point wax compared to 1.17 described by Howell and Jessen: gm/IOO ml for the 186 0 F melting paraffin deposited. point wax solution. Therefore, the DETERMINATION OF RATES OF Before the test pipes were rein­ difference in the rates of deposition PARAFFIN DEPOSITION stalled for the next run, they were for the'Se two solutions may be at­ thoroughly cleaned inside and out tributed to the concentration of free As shown in Fig. 1, flow rates by wiping several times with a kero- wax in suspension at the temperature were controlled by Valves Band C. During low rates of flow, part of the fluid circulated by the pump was by­ passed through Valve B into the oil reservoir. Proper manipulation of Valves Band C made it possible to adjust the flow to any described rate into the upstream header and through the individual test sections of pipe. Prior to each run, Valve A was closed and Valve B opened in order to circulate the oil and thus dislodge and dissolve from the bottom of the storage reservoir any paraffin that may have settled between runs. Velocity of flow in the test pipe sections was determined by measur­ ing the pressure differential across each pipe with a manometer. The difference between the inlet and outlet oil temperatures was only 1 to 2° F. This difference in tempera­ ture was constant throughout each FIG. 2-DEPOSITION ApPARATUS.

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FIG 4---EFFECT OF VELOClTY ON RATE OF FIG. OF VELOCITY ON RATE OF 3~EFFECT DE~OSITION FOR 186°F MP WAX IN FIG. 5~EFFECT OF VELOCITY ON RATE OF DEPOSITION FOR 200° F MP WAX IN KEROSENE AT 110° F. CLOUD POINT OF DEPOSITION OF BIG FOOT CRUDE OIL AT KEROSENE AT F. CLOUD POINT OF 110° SOLUTION IS 120° F. 102° F AND WATER TIo:MPERATURE SOLUTION IS 120° F. OF 70° F. tion decreased rapidly. Results of of the runs. Predictions concerning flow tests on Big Foot crude oil, Fig. fin deposition to increase with veloc­ possible paraffin accumulation in oil­ 5, illustrate the typical shape of the ity to velocities approximately equal field tubular goods must be based curves obtained. to the transition velocity (Reynolds upon a thorough know!edge ?f the number 1,980) is clearly shown in Downloaded from http://onepetro.org/trans/article-pdf/213/01/80/2179130/spe-968-g.pdf by guest on 29 September 2021 At Reynolds numbers greater than concentration and meltmg pomt of Fig. 10 on the curve for the rat~ of 4,000, the plastic pipe surfaces ~ere the paraffin in solution in the crude paraffin deposition in the steel plp~. free of any paraffin accumulatIon; oil. Not much difference was noted m however since some oil remained on Rate of paraffin deposition vs fl~w the relative effectiveness in any of the of the pipes after draining, rate was determined for crude OIls insid~ the plastic pipes for reducing depo­ the paraffin was determine.d analyti­ from several fields* known to deposit sition. paraffin. Analyses of the different oils cally in the manner preVIOusly de­ scribed. High viscous drag was obtained at are given in Table 1. relatively low flow rates in the more The rate of paraffin deposition at Figs. 6 and 7 show paraffin depos~­ viscous fluids. This may account for tion-velocity curves for crude OIl all velocities and temperatures was the fact that no deposition was ob­ from well No. DU-24-1, located on greatest in steel pipe but considerab!e tained from the Oklahoma crude oil the eastern end of the Delhi field, paraffin deposition was also found m which had a viscosity of 29.5 cp com­ butyrate pipe. The least amount ?f which was reported experiencing co?­ pared to an average of 4 cp for the sider'able difficulty from paraffrn paraffin accumulation was .noted ~n other crude oils examined. Even the rigid PVC and kralasttc plastIc deposits. Figs. 8 and 9 represent data though a velocity of 5.1 ft/sec, corre­ pipes. All plastic pipe tested showed on crude oil taken from well No. sponding to a Reynolds number of DU-184-1, located in the western less tendency for accumulatio? of 678, was reached, no measurab~e portion of the field. These we!ls a:e paraffin than did steel or alum mum deposition was obtained from t~IS pipe. equipped with Tube-Kote tubmg. m crude oil when flowing through % -m. order to reduce paraffin accumulatIOn pipe. Use of 2-in pipe enabled test In experiments using 2-in. pipe which occurs at low withdrawal size the 3-m plastic lined fiber glass observations over a range of Rey­ rates: At rates above 200 ~OPD nolds numbers up to 1,500. In every pip~ showed consistently .rower rapid deposition of paraffin m the quantities of deposit. than dId t~e instance, paraffin deposition was sub­ tubing is prevented. A rate of 200 stantially lower than with other. crude other resin-coated pIpe or plastIC BOPD through 2-in. tubing corre­ pipe. Again, more deposition. oc­ oils used in the flow expenmen~s sponds to a Reynolds number of 2,0~2 curred in the steel and alummum through 2-in. pipe. Whether thIS which is the approximate velocIty smaller amount of accumulation was pipe, although the wi~e v~riation at which turbulent flow begins. Max­ occasioned solely by the viscous drag apparent when using 314 -m. pIpe was imum rate of deposition was obtained is questionable since ~his particul~r not noted. in the laboratory at a velocity corre­ crude oil had a much hIgher asphaltIC A gradual increase in th~ rate .of sponding to a Reynolds number of content. paraffin deposition was obt~med wIth 846. A Reynolds number of 2,042 increased velocity, the maxImum rate determined from the field data (200 Two possible mechanisms f.or being reached when the flow changed BOPD through 2-in. tubing) corre­ paraffin deposition may be conSId­ from viscous to turbulent flow. At sponds to a linear velocity of 1.45 ered. First, deposition of paraffin from the crude oil at the pipe walls; higher velocities the rate of deposi- ft/sec in the laboratory apparatus. ~t this linear velocity, paraffin depOSI­ that is, growth of the paraffin par­ ticles in place at pipe surfaces, and *Big Foot field, Frio County, Tex.; Delhi tion in the % -in. plastic pipe was field Franklin Parish, La.; Howard Glfs­ second, paraffin crystals may occur cock field, Howard County, Tex.; Pren Ice substantially reduced. field, Yoakum County, Tex.; and the Camp or be present in the oil and these N. W. pool, Okla. The tendency for the rate of paraf- may subsequently be deposited. Th.e first mechanism for paraffin depOSI­

TABLE 1 - ANALYSIS OF CRUDE OILS tion seems to be the controlling factor Camp NW Howard Delhi Delhi Big since the greatest deposition was ob­ Pool Glasscock DU·184-1 DU-24-1 Foot Prentice Gravity, °API (60"F) .. ..._ 26 29.9 40 39 38 30.5 tained from the crude oils when Viscosity, cp (100°F) .... ___ 29.5 10.2 3.2 4.3 4.0 3.5 Cloud Point, °F______78 97 105 119 113 97 maintained at temperatures above or Paraffin Wax, per cent. __ 2.11 3.39 4.35 4.32 3.79 2.21 near the cloud point prior to cooling Pentane Insolubles, per cent 3.73 1.18 1.37 1.19 0.552 3.41 Benzene Insolubles, per cent _ 0.157 1.128 0.00 0.00 0.0018 0.115 in the piping system. For example, Melting Point of Paraffin Wax, OF _ .... 125 121 122 128 120 133 the temperature of the oil in Fig. 8

PETROLEUM TRANSACTIONS, AI ME 82 ... ~.

__0- ____..un-oO'''C .... 3-¢-Q-··... ·ITI. g'o ~.r~'D.". ii ~ o ~ ~ 0------<) ''''c , ~ 5 ...... """ •• < ii ~ ~ :~.~~ ..:~: 0------0 Stul ~ 4------¢-KrQlosl'e z ' ...... 811Iy' .. ,t ~~~--~--~~,~~~~ ~ ~FI'9IdPVC FT PER SEC --il- ~ - "it ~ 0'5-0----,--+---+-~t__-~----___I !c-_-+_----.--:V.~OLOCITY, F~a PER SEC e'o - - t~-~ FIG. 8-EFFECT OF VELOCITY ON RATE OF 2 '.0 ~UNOI.O' NUMIEII )C 10- ..------<0--.1 DEPOSITION OF DELHI DU-184-1 CRUDE FIG. 10-EFFECT OF VELOCITY ON RATE OIL AT 106° F AND WATER TEMPERATURE OF DEPOSITION OF HOWARD GLASSCOCK FIG. 6-EFFECT OF VELOCITY ON RATE OF OF 80° F. DEPOSITION OF DELHI DU-24-1 CRUDE OIL CRUDE OIL AT 85° F AND WATER TEM· AT 108° F AND WATER TEMPERATURE PERATURE OF 70° F. OF 70° F.

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40 60 ---'00 FIG. ll-EFFECT OF VELOCITY ON RATE ".yookl.'-Iumo.,.'O·2 FIG. 9-EFFECT OF VELOCITY ON RATE' OF DEPOSITION (2-IN. PIPE SIZE) OF DEPOSITION OF DELHI DU-184-1 CRUDE FIG. 7-EFFECT OF VELOCITY ON RATE OF HOWARD GLASSCOCK CRUDE OIL AT 88° F OIL AT 90° F AND WATER TEMPERATURE DEPOSITION (2-IN. PIPE) OF DELHI AND WATER TEMPERATURE OF 70° F. DU·24·1 CRUDE OIL AT 105° F AND WATER OF 70° F. TEMPERATURE OF 70° F. dependent solely on the cooling at the with the steel pipe took place at somewhat higher velocities than for was 1 ° F higher than the cloud inner walls of the pipe, but may be plastic pipes. To explain this appar­ point, while in Fig. 9 the temperature controlled by the adhering tendency ent irregularity, it is necessary to of the oil was 15 ° F below the cloud of the solid on the exposed surface. cOll5ider the role of thermal conduc­ point before introduction into the Occurrence of a gradual build-up tivity of the pipe materials and the test pipes. In the first instance deposi­ in the deposition rate may be ex­ effects of temperature upon the ad­ tion could be possible only by growth plained on the basis of mass transfer herence of the paraffin deposited. of the paraffin particles at pipe walls, of the paraffin particles. Less paraffin while in the latter case deposition is carried past a given point on the The loss of temperature of the would be possible by both mechan­ pipe wall in a specified interval of crude oil is the major factor involved isms. There was not much difference time during low rates of flow. As the in the formation of paraffin deposits. in rates of paraffin deposition within flow is increased, more and more The hardness of the paraffin deposit the steel pipe at these temperatures; paraffin is carried by the moving oil is also directly related to the tempera­ however, approximately three times stream providing a greater opportun­ ture of the deposit. Paraffin deposits as much paraffin was deposited in the ity for deposition upon the surface are more crystalline at lower tem­ plastic pipes at low velocities when of the pipe. However, the viscous peratures and, therefore, are more the temperature of the oil was main­ drag exerted by the stream tends to tightly held together. Steel, having tained slightly above the cloud point remove the accumulation and, at high the greatest thermal conductivity of as when the oil temperature was con­ velocities, becomes equal to or may any of the materials testeu, permitted trolled at 15° F below the cloud exceed the shear stresses within the the greatest loss of heat from the oil point even though the final oil tem­ deposited paraffin and literally tear and, as a result, a lower terrperature perature was 16° Flower. the paraffin deposit apart. Paraffin at the inner pipe wall. The attain­ There is, of course, another factor deposited at high rates of flow was ment of higher velocities in the steel which may explain this difference in observed to be considerably harder pipe before the the maximum rate of the quantity of paraffin deposited, than paraffin deposited at lower rates deposition was reached may further namely, the lower heat conductivity of flow. The increase in both viscous be explained by the variation in phys­ of the plastic pipe. That is, when drag and shearing stresses in the ical characteristics of the paraffin operating with oil temperatures above paraffin deposits at high rates of flow deposit formed. the cloud point, initial solid phase possibly accounts for the gradual de­ The relative wettability of the buty­ occurrence is postulated to take place crease in deposition rate at higher rate, kralastic, and rigid PVC plastic directly on the wall of the pipe and, velocities rather than a sudden and materials as reflected by the contact therefore, it is reasonable to expect complete elimination of paraffin depo­ angle measurements on the plastic that deposition should be much sition as would be expected if the materials of saturated solutions of greater on steel than on plastic. On shearing stress of the paraffin re­ different melting point paraffins in the other hand, when operating at ini­ mained constant and was suddenly kerosene is shown in Fig. 14. The tial oil temperatures below the cloud exceeded by the viscous drag of the contact angle increased slightly with point, a solid phase is presumed pres­ flow stream. the melting point of the paraffin wax ent and deposition would not be The maximum rate of deposition in solution, indicating that crude oils

113 ,VOL. 213, 1958 0--0 Steel Q----Q Epoxy Resin -..3-M ¢----¢ Aluminum fr------I:1 PVC (HI) A-----.l PVC (U) '"~2~--~----~------:;;;

FIG. l4-VARIATION OF CONTACT ANGLES FOR SATURATED KEROSENE SOLUTIONS AT 75° F.

creased deposit of paraffin results, as 2 3 4 compared with that obtained when Velocity. Ft, Per Sec. the oil has been cooled below the o 6 7 8 9 'et II 12 13 14 15 16 cloud point prior to circulation Reynolds Number >0: 10 through the pipe. FIG. 12-EFFECT OF VELOCITY ON RATE OF DEPOSITION (2-IN. PIPE 4. The rate of accumulation of

SIZE) OF OKLAHOMA CRUDE OIL, DENNY No.2, AT 85° F AND WATER Downloaded from http://onepetro.org/trans/article-pdf/213/01/80/2179130/spe-968-g.pdf by guest on 29 September 2021 TEMPERATURE OF 65° F. paraffin on plastic pipe seems re­ lated to the degree of wettability by the crude oil. 5. Although plastic pipe may not --~ entirely eliminate paraffin deposits, the rate of deposition on plastic pipe ~ or plastic lined pipe is substantially ~ )- ~ .. lower than on steel or aluminum pipe. ~ ~ _Iii "-....!...... r-.,. ~ -...... ACKNOWLEDGMENTS w '-. o ~ 1-- ~ The authors wish to acknowledge o .. ~- ...... Iii ...... with thanks the help of Wesley W. ~.2 -~ t--o 0--051 •• 1 Smith and Charles Fraser who as­ ~.. e----e Epoxy Resin Q. - sisted with some of the laboratory e--e3-M P-----):f Aluminum work. They are indebted to the Carl­ _PVCIHIl on Products Corp., Cleveland, Ohio, ...... PVClill for financial assistance on the project o 0 I 2 3 4 5 and for permission to publish the I I Velocity, It/.ec I results presented in this paper. o 2500 5000 7500 10,000 12,500 Reynolds Number FIG. 13-EFFECT OF VELOCITY ON RATE OF DEPOSITION OF PRENTICE REFERENCES FIELD CRUDE OIL AT 87" F AND WATER TEMPERATURE OF 67" 'F. I. Shock, D. A., Sudbury, J. D., and Crockett, J. J.: "Studies of the Mech­ containing high melting point paraf­ greater amounts of asphaltic con­ anism of Paraffin Deposition and Its fin waxes would tend to wet these stituents. Control," lour. Pet. Tech. (Sept., materials to a lesser degree than 1955) VII, No.9, 23. crude oils containing lower melting 2. Bowers, E. F., and Renfro, H.: "Para­ CONCLUSIONS ffin Removal in South Texas," Oil and point paraffins. Gas lour. (1947) 46, No.4, 134. 1. Rate of paraffin deposition in Table 2 shows the relative wetta­ 3. Reistle, C. E., Jr.: "Paraffin and Con­ bility of various plastic materials by steel pipe varies with flow rate, reach­ gealing-Oil Problems," Bull., USBM the crude oils used in this investiga­ ing a maximum just prior to change (1927) 7, 348. tion. The contact angles of these from viscous to turbulent flow and 4. Nathan, C. c.: "Solubility Studies on crude oils agreed fairly well with decreasing with increased turbulence. High Molecular Weight Paraffin Hy­ 2. Deposition of paraffin on vari­ drocarbons Obtained from Petroleum those found when using a saturated Rod Waxes," Trans. AIME (1955) solution of kerosene and 122°F melt­ ous kinds of plastic pipe shows the 204, 151. ing point paraffin wax. The variation same general pattern with regard to 5. Gruse, W. A., and Stevens, D. R.: in contact angle on anyone plastic flow rate. The amount of accumula­ Chemical Technology of Petroleum, material was small except for the tion noted, however, was appreciably McGraw-Hill Book Co., Inc., N. Y. Camp N. W. pool and the Howard less in every instance. (1942) Chap. XXII. Glasscock field crudes. This may be 3. When cooling of the oil from 6. Stegemeier, G. L.: "The Relationship of Relative Permeability to Contact due to differences in composition temperatures above the cloud point Angles," MS Thesis, The University since the latter crudes contained takes place at the pipe wall, an in- of Texas (Jan. 1954). 7. Howell, J. N., and Jessen, F. W.: "Determination of the Viscosity-Tem­ TABLE 2 -- CONTACT ANGLES OF CRUDE OILS ON PLASTIC MATERIALS perature Relationship for Crude Oils Fluid PVC Kralasfic Butyrate 3·M Epoxy Resin with the Ultra- Viscoson," Trans. Delhi DU-24-1 17 Spreads Spreads Spreads Spreads Delhi DU·184·1 17 Spreads Spreads Spreads Spreads AIME (1956) 207, 330. Camp NW Pool_ 20 12 10 Spreads Spreads S. Private communication: L. F. Ellison, Howard Glasscock _ 17 9 2·3 Spreads Spreads Big Foot 17 Spreads Spreads Spreads Spreads Sun Oil Co., Delhi, La. (April ]2, Water ------74 70 52 68 53 1955). ***

PETROLEUM TRANSACTIONS, AIME