wells were completed as oil producersand 149 were completed as gasproducers while 77 were dry andabandoned, result ing in a success rate of92%. In addition, 29 other wells weredrilled in southeast New Mexico in 1996;these other wells include injection wellsfor waterfloods and saltwater disposalwells. Drilling activity was concentrated inPermian reservoirs on the Northwestshelf and Central Basin plat form andin the Delaware Basin.

Upper Guadalupian reservoirs

Shallow (2,000-4,000 ft) oil andassociated gas reservoirs of the Yates andQueen Formations (Permian: UpperG uadalupian) were major targets ofdevelopment drilling in 1996.Approximately 100 wells werecompleted in these zones. Drilling wasprimarily for development in maturefields on the Central Basin platform in LeaCounty. Activity was widespread,with significant numbers of developmentwells completed in Yates and Queenreservoirs in the Langlie–Mattix, Jalmat,and Eumont pools of Lea County.

San Andres and Grayburg reservoirs

Oil and associated gas reservoirs in theshallow (2,000-5,000 ft) San Andres andGrayburg Formations (Permian: lowerGuadalupian) were primary targets of de-velopment drilling in 1996.Approximately 270 wells werecompleted in these zones. Drillingwas primarily for development ofmature fields on the southern part ofthe Northwest shelf in northern Eddyand Lea Counties. Activ i ty waswide spread with wells drilled in 26different pools. Drilling was concentratedin the Grayburg–Jackson pool of EddyCounty where 96 wells were drilled. Majordevelopment also took place in the RedLake, Artesia, and Millman East poolsof northern Eddy County and in theMaljamar and Vacuum pools ofnorthern Lea County. Althoughexploration along the mature SanAndres and Grayburg trends was lim-ited, two significant discoverieswere made. Production wasestablished from the San AndresFormation in the Chi Operating No. 1Oyster (34) in central Lea County,and oil was discovered in the MarbobEnergy No. 1 Katie Elder State (2) incentral Chaves County.

Delaware Mountain Group sandstones

Basinal sandstone reservoirs o fthe Delaware Mountain Group (Permian:Guadalupian) continued to be one ofthe mos t ac t ive p lays in sou theas tNew Mexico. During 1996,approximately 170 wells were drilled insearch of oil in these reservoirs in theDelaware Basin. Depth to productiontypically ranges from 5,000 to 8,000 ftbut can be as shallow as 2,000 ft in thenorthern part of the Delaware Basin.

Exploration was more active than inprevious years, with 14 exploratorywells drilled. Development was mostly byinfill drilling and conservativestepouts from known production; thedevelopment success rate of Delawarereservoirs exceeded 90% in 1996.Development wells were drilled in 46oil pools. The Red Tank West, Avalon,Happy Valley, Ingle Wells, and LeaNortheast pools were the most in -tensely developed Delaware reservoirsin 1996. As in the past few years,most of drilling was for oil in the BrushyCanyon Formation, the lowermost of thethree sandstone-bearing formationsthat constitute the Delaware.

Three significant discoveries of oil in theDelaware were made during 1996.Oil w a s d i s c o v e r e d i n D e l a w a res a n d stones in the Santa Fe Energy No.1 Corral Fly Unit (17) in southeastEddy County. Oil was also discoveredin Delaware sandstones in the SantaFe Energy No. 1 Turquo ise 30Federal (41) and in the Manzano OilNo. 1 Bobwhite SV Federal (33) alongthe eastern edge of the Delaware playin Lea County.

Bone Spring basinal sediments

Basinal allochthonous carbonates andsandstones of the moderately deep(6,00010,000 ft) Bone Spring Formation(Permian: Leonardian) were intenselydrilled in 1996. Approximately 60 wellswere drilled for oil in these reservoirswithin the Delaware Basin. The BoneSpring play had been relativelyinactive for the past few years asshallower targets in the DelawareMountain Group were given prefer-ence for exploration anddevelopment drilling. Developmentwells were drilled in 22 oil pools ineastern Eddy and western LeaCounties. Drilling activity was mostintense in the Red Tank pool of west-central Lea County. Elevendevelopment oil wells weresuccessfully completed in the Red Tankpool.

Exploration for hydrocarbons inBone Spring reservoirs surged in 1994 andthis exploratory activity continued into1995 and 1996. In many cases, BoneSpring discoveries were made byreentering older we l ls that hadproduced from deeper reservoirsand had subsequently beenabandoned in those deeperreservoirs. Along the western edge ofthe play, oil was found in the BoneSpring in two wells, the PenwellEnergy No. 1 Rookie 7 State (12) andthe Ray Westal l No. 1 Riverbend (14).In the south-central part of the BoneSpring play, oil was found in the PenwellEnergy No. 1 Ore Ida 14 Federal (15),the Bass Enterprises No. 123 PokerLake Unit (16), and the YatesPetroleum No. 7 Haracz AMO Federal (40).Oil was discovered in the eastern partof the play in the Yates Petroleum No.2 Alphabet Unit (35) and the BTA OilProducers No. 1 Chiso C 8711 JV-P (38).

Yeso shelf sedimentsShallow shelf carbonate reservoirs

of the Yeso Formation (Permian:Leonardian) were actively drilled in1996. One hundred and twenty-sixdevelopment wells were drilled in 28pools on the Central Basin platformin southern Lea County. There wasalso some minor development of oilpools astride the shelf edge in southernEddy County. Production is obtainedf rom a l l f ou r me mbe rs o f theYe so (descending): Paddock, Blinebry,Tubb, and Drinkard members. Inmany of the pools, production fromtwo or all three of these zones iscommingled. In some pools, Yesoproduction is commingled with oilproduction from underlying Abo(Permian: Wolfcampian) carbonates.Pools with the most drilling activity in1996 were the Blinebry pool, the Teaguepool, and the Dollarhide pool of southeastLea County.

There was limited exploration for hy-drocarbons in Yeso reservoirs. Onesignificant discovery was made. Oil wasfound

82 November 1997 New Mexico Geology

in the upper Yeso in the MarbobEnergy No. 1 Barnsdall Federal (7) onthe southern margin of the Northwestshelf. This discovery is located alongthe northern margin of the Yeso playin areas where Yeso production issparse.

Abo sandstone and carbonate reservoirs

Development of sandstone reservoirsin the Pecos Slope and Pecos Slope Westgas pools continued slowly in 1996 withonly 17 development wells completed inthese "tight" gas reservoirs. There wasonly limited development of oil-bearing Aboshelf-margin carbonate reservoirs onthe southern edge of the Northwest shelfand on the Central Basin platformwith 32 wells drilled in nine reservoirs.Activity was concentrated in theMonument Abo pool of central LeaCounty where the 17 development wellswere successfully completed. Twosignificant exploratory discover ies weremade in the Abo carbonates insoutheastern Lea County (42, 44).

Wolfcamp carbonates

Moderately deep (9,000-11,000 ft)carbonate reservoirs in the WolfcampGroup (Permian: Wolfcampian) weredeveloped at a limited rate in 1996.Twelve development oil wells and ninedevelopment gas wells were completedsuccessfully in 14 pools in northernand central Eddy County and insouthern and central Lea Counties.However, exploration for Wolfcamphydrocarbons was vigorous and foursignificant exploratory discoverieswere made during 1996. In EddyCounty, oil was discovered in theWolfcamp i n the Texaco No. 3 DD 24Federal (11) and in the Penroc Oil No. 1PFI Amoco 19 Federal (13). Oil wasdiscovered in the Wolfcamp in LeaCounty in the Manzano Oil No. 1 SVChipshot (26) and in the Enron No. 1Jamaica Olson Federal (43).

Upper Pennsylvanian carbonates

Moderately deep (7,000-10,000 ft) Ciscoand Canyon (Upper Pennsylvanian)carbonate reservoirs continued to bedeveloped aggressively in 1996. Seventy-two development wel ls weresuccessful ly completed in ninereservoirs. Activity was concentrated inthe Dagger Draw North pool where 27development oil wells were successfullycompleted and in the Dagger DrawSouth pool where 22 development oilwells and one gas well were success-fully completed. Fifteen developmentwells were completed in the IndianBasin gas pool that lies justsouthwest on the Dagger Draw oilpools and forms the gas cap to thosepools . The Dagger Draw North andDagger Draw South pools are examples ofunderdeveloped reservoirs thatproduced minor volumes of oil foralmost 20 years. Upon realization that

substantial oil resources remainedunproduced in these reservoirs,drilling programs were instituted totap into those resources. The resultwas an immediate increase inproduction, and Dagger Draw Northand Dagger Draw South quicklybecame two of the most productiveoil pools in southeast New Mexico. In1995, they produced 8 million bbls oil,approximately 14% of the state's totaloil production. There were fivesignificant exploratory discoveries inUpper Pennsylvanian carbonatesduring 1996 (5, 8, 20, 21, 30).

Strawn reservoirs

De ve lopment o f mode ra te l ydeep (10,000-12,000 ft) Strawn (MiddlePennsylvanian) reservoirs continued in1996. Development of existingreservoirs was slow, with only 13development wells successfullycompleted in 12 pools. Exploration foroil and gas in Strawn carbonatereservoirs was also subdued. Onlyone discovery was made. Oil wasdiscovered in Strawn carbonates in theChesapeake Operating No. 1 Chambers 7(25). Initial potential was animpressive 482 bbls oil per day and800 thousand ft3 gas per day from 10ft of pay.

Atoka and Morrow "deep gas" reservoirs

The deep (10,000-14,000 ft) gasreservoirs in the Atoka and MorrowGroups saw limited development withonly 37 development wells completedsuccessfully in 28 pools in 1996.Exploratory drilling was also subdued,but several discoveries were made.Exploration was for gas in Morrowreservoirs (wells 6, 31, 37, and 39) andalso for oil in the shallower Atokareservoirs (wells 23, 29, 32, and 36).Although the Atoka produces gasthroughout most of southeast NewMexico, an oil play of modest size hasemerged in the Atoka during the pastfew years in northeast Lea County.

Devonian, Silurian, andOrdovician reservoirs

Exp lora t ion fo r o i l inse ismica l ly de f ined structuraltraps in the lower Pa leozo icsec t ion was strong on the CentralBasin platform and on the Northwestshelf. Many traps in the lower Paleo-zoic are formed by fault-boundedanticlinal closures. Three exploratorywells were dril led successfully on theNorthwest shelf in Chaves County (wells1, 3, 4). Five additional exploratorydiscoveries were made in Lea County(wells 18, 19, 22, 27, 28). Exploration forstructural traps in the Devonian,Silurian, and Ordovician sections isexpected to remain strong through1997. Better definition of therelatively small structures that formtraps in the lower Paleozoic has beenmade possible recently by new and

affordable 3-D seismic techniques,although this new technology has notyet been fully utilized to define suchfactors as seal integrity or migrationpathways. These latter factors areapparently important when consider-ing entrapment of hydrocarbons inthe lower Paleozoic section on theNorthwest shelf.

S a n J u a n B a s i n ,northwest New Mexico

Drilling activity increased slightlyduring 1996 in the San Juan Basin.There were 424 completions duringthe year, an increase of 4% from the407 completions in 1995. The successrate was 95%, with 381 wells completedas gas producers, 22 wells completedas oil producers, and 21 wells pluggedand abandoned. Drilling concentrated ondevelopment of gas reservoirs in theFruitland coals (Cretaceous), PicturedCliffs and other Mesaverde sandstones(Cretaceous), and Dakota sandstones(Cretaceous).

Fruitland coalbed methane reservoirs

Gas reservoirs of the FruitlandFormation (Upper Cretaceous) continuedto be aggressively developed in 1996, but ata decreased rate from previous years. Ap-proximately 60 wells were completedin the Fruitland. Most of these wellswere drilled in coalbed methanereservoirs of the giant Basin pool ineastern San Juan County.

Pictured Cliffs Sandstone

Gas reservoirs in the PicturedCliffs Sandstone (Upper Cretaceous) weremajor targets for exploratory anddevelopment drilling in 1996. More than60 wells were completed in thesereservoirs. Development dril l ing wasconcentrated in the Kutz West andFulcher Kutz pools o f northeast SanJuan County. Exploration for gas inPictured Cliffs sandstones was subduedin 1996 with most exploratory drillingconcentrated on developing and extendingpreviously discovered gas.

Mesaverde sandstones

Development of gas reservoirs inMesaverde sandstones (UpperCretaceous) remained strong during1996. Approximately 150 developmentgas wells were co mple ted inMesaverde sandstones. Almost all ofthese wells were completed in theBlanco pool of northeast San Juan andnorthwest Rio Arriba Counties. Many ofthese wells were completed as dual pro-ducers from gas reservoirs in Mesaverdesandstones and in Dakota sandstones.

Exploration for gas in theMesaverde was minimal in 1996. In thesouthern part of the San Juan Basin,the High Plains Petroleum No. 1 Red DogFederal (49) was

New Mexico Geology November 1997 83

84 November 1997 New Mexico Geology

New Mexico Geology November 1997 85

drilled to a total depth of 1,154 ft to testMesaverde sandstones, but productionwas not established.

Gallup sandstone

Oil reservoirs in the Gallup sandstone(Upper Cretaceous) saw milddevelopment activity during 1996. Elevendevelopment wells were completedsuccessfully in seven reservoirs and anadditional five development wells wereplugged and abandoned. Activity wasscattered among the Bisti, Bisti South,Devils Fork, Lybrook, Angel Peak, ChaCha, Verde, and Horseshoe pools. Two

significant exploratory discoveries weremade. Oil was discovered in theGallup in the Dugan Production No. 1Hop Sing well (47). Gas was discovered inthe Gallup in the Meridian Oil No. 5 RiddleB well (45).

Dakota sandstones

Oil and gas reservoirs in sandstones ofthe Dakota Group (Upper Cretaceous)were developed aggressively in 1996. Fiveoil wells and 97 gas wells were completedin Dakota reservoirs. Drilling for gas wasconcentrated in the giant Basin pool ofnortheast San Juan and west Rio ArribaCounties. Oil drilling was concentrated in

the Lindrith West pool of southeastSandoval County. In many wells,production from the Dakota iscommingled with production fromMesaverde, Gallup, and Granerossandstones (Upper Cretaceous).

Entrada Sandstone

There was significant exploration forhydrocarbons in the Entrada Sandstone(Jurassic) in northwest New Mexico dur-ing 1996. In the southern part of the SanJuan Basin, the Merrion Oil and Gas No. 1Sarcio (48) was drilled to a total depth of3,552 ft to test the Entrada. The well wasabandoned after water was recovered on adrill-stem test of the Entrada. On the east-ern flank of the San Juan Basin, theThompson Engineering No. 1 Gonzales(52) was abandoned at a total depth of2,606 ft in the Entrada without establish-ing production.Horizontal wells were successfully

drilled in the Papers Wash pool ofnortheast McKinley County, the SnakeEyes pool of southeast San Juan County,and the Media and Eagle Mesa pools ofnorthwest Sandoval County. These wellswere completed in the uppermost part ofthe Entrada and presumably are designedto minimize water coning and reduce theamount of water produced from eachwell. Vertical Entrada wells typically pro-

86 November 1997 New Mexico Geology

duce high volumes of water after just two orthree years of production; productionbecomes uneconomic in some of thesewells because of the high cost of pumpingthe oil and water and the high cost ofwater disposal.

Pennsylvanian carbonates

Development of hydrocarbons inPennsylvanian carbonate reservoirs wasmoderate during 1996. Four developmentgas wells were successfully completed in theBarker Creek field of northwest San JuanCounty. Although modest production ofoil and gas is obtained from Pennsylvanianreservoirs on the western flank of the SanJuan Basin, the Pennsylvanian section hasbeen tested by relatively few wellsthroughout most of the basin and remains apromising exploratory target. BothBurlington Resources and Conoco haveongoing exploratory programs targeted atPennsylvanian reservoirs.

Albuquerque Basin

In central New Mexico, Davis Oil Corp.and Vastar Resources discontinued explo-ratory efforts in the Albuquerque–BelenBasin. These exploratory efforts have re-sulted in drilling two wells with Davis Oilas the operator. The Davis No. 1-Y Tamara(53) was spudded in late 1995 in the north-ern part of the basin. It was drilled to atotal depth of 8,732 ft in the Chinle Forma-tion (Triassic) and was abandoned in 1996without reported shows. The Davis OilNo. 1 Angel Eyes (54) was spudded in thesouthern part of the basin in early 1996 andabandoned at a total depth of 8,074 ft insands of the Santa Fe Group. The well wasnot drilled to a sufficient depth to penetrateUpper Cretaceous sandstones, the primaryexploratory objectives in the basin. TwiningOil Company has continued to acquireleases in the southern part of the basin.

Exploratory interest in the AlbuquerqueBasin has been intermittent. The lastexploration was in the early 1980s whenShell and UTEX Oil Company drilledeight wildcat wells in the basin in searchof hydrocarbons in the Cretaceous section.Although production was not establishedin those wells, significant shows of gaswere found, and analyses of drilling indicatethat the necessary parameters forcommercial production are present withinthe basin. Black (1982, 1989) has summa-rized the petroleum geology and the his-tory of oil and gas exploration in theAlbuquerque Basin.

Northeast New Mexico

Northeast New Mexico saw significantexploratory activity and plans for signifi-cant development in 1996. A petroleumexploration well was completed in theTucumcari Basin. Plans were made for fur-ther development of carbon dioxideresources in the Bravo dome. In addition,

plans were considered to develop andproduce coalbed methane in the RatonBasin.

In the Tucumcari Basin, the LabradorOil Company No. 1 Mescalero (57) wasdrilled to a total depth of 14,597 ft inPrecambrian rocks. The well had beenscheduled to drill to a total depth of 18,000ft, but drilling ceased after the drill collarsand drill pipe were lost in the hole below9,000 ft. There was also extensive leasing ofacreage in the basin by Circle Energy andRio Grande Resources during 1996. It isexpected that drilling will follow that leasingactivity. Commercial production ofhydrocarbons has not been obtained fromthe Tucumcari Basin, but marginally com-mercial discoveries of both oil and gaswere made in the early 1980s (Broadheadand King, 1988); these discoveries werenever exploited. Primary objectives in thebasin are Pennsylvanian sandstones andlimestones and Lower Permian dolostones.

Pennzoil was reported to still be consid-ering a program to develop and producecoalbed methane in the Vermejo Forma-tion (Cretaceous) in the Raton Basin. From1989 through 1991, Pennzoil drilled morethan 30 wells as part of a pilot program totest and evaluate coalbed methane in thebasin. Primary use of the gas, if developedand produced, will be to generate electricityat a proposed power-generating plant inthe city of Springer.

Elsewhere in northeast New Mexico,Amoco continued development of theBravo dome carbon dioxide gas field ofUnion County. Amoco drilled 20 newwells to enhance production. In HardingCounty, northwest of the Bravo domefield, the Amoco No. 1 Bueyeros (58) wasdrilled to a total depth of 5,378 ft inPrecambrian rocks in search of additionalcarbon dioxide resources, but productionwas not established. Almost all carbondioxide produced from the Bravo dome

field is transported through pipelinestothe Permian Basin where it is used in en-hanced oil recovery. Currently, most of theenhanced -recovery projects are in theTexas part of the basin (Oil and GasJournal, 1996). Some carbon dioxide isconverted to dry ice and bottled, liquidcarbon dioxide at small processing facili-ties in Union and Harding Counties.

In northernmost Union County, federallands near the Colorado State Line havebeen leased. Although the objectives ofthis lease play are not known, they mayinvolve Morrow sandstones (Lower Penn-sylvanian) that produce oil in southeastColorado.

Southwest New Mexico

Two petroleum exploration wells weredrilled in southwest New Mexico during1996 in the Chupadera Basin of eastern So-corro and northwestern Lincoln Counties.The Manzano Oil No. 1 Cathead Mesawell (55; Fig. 2) was abandoned at a totaldepth of 6,190 ft. The gas detector on themudlogging unit recorded an excellentgas show in the lower part of the hole. TheManzano Oil No. 1 Spaid Buckle well (56)was abandoned at a total depth of 4,871 ftwith no reported shows.

ACKNOWLEDGMENTS—Roy Johnsonof the New Mexico Oil ConservationDivision reviewed the manuscript. BenDonegan and Jack Frizzell provided helpfulinformation and discussion on the Chupa-dera Basin play. Kathy Glesener draftedthe illustration.

New Mexico Geology November 1997 87

References

Black, B. A., 1982, Oil and gas exploration in theAlbuquerque Basin; in Wells, S. G., Grambling, J.A., and Callender, J. F. (eds.), AlbuquerqueCountry: New Mexico Geological Society,Guidebook 33, pp. 313-324.

Black, B. A., 1989, Recent oil and gas exploration inthe northern part of the Albuquerque Basin; inLorenz, J. C., and Lucas, S.G. (eds.), Energy fron-tiers in the Rockies: Albuquerque GeologicalSociety, p. 13.

Broadhead, R. F., and King, W. E., 1988, Petroleumgeology of Pennsylvanian and Lower Permianstrata, Tucumcari Basin, east-central NewMexico: New Mexico Bureau of Mines andMineral Resources, Bulletin 119, 75 pp.

Cather, S. M., and Johnson, B. D., 1984, Eocene tec-tonics and depositional setting of west-central

New Mexico and eastern Arizona: New MexicoBureau of Mines and Mineral Resources, Circular192, 33 pp.

Kelley, V. C., 1978, Geology of the Espanola Basin,New Mexico: New Mexico Bureau of Mines andMineral Resources, Geologic Map 48, scale1:125,000.

Kottlowski, F. E., and Stewart, W. J., 1970, TheWolfcampian Joyita uplift in central NewMexico: New Mexico Bureau of Mines andMineral Resources, Memoir 23, pt. I, pp. 1-31.

Meyer, R. F., 1966, Geology of Pennsylvanian andWolfcampian rocks in southeast New Mexico:New Mexico Bureau of Mines and MineralResources, Memoir 17, 123 pp.

Molenaar, C.M., 1977, Stratigraphy and deposi-tional history of Upper Cretaceous rocks of theSan Juan Basin area, with a note on economicresources; inFassett, J. E., and James, H. L. (eds.),

San Juan Basin III (northwestern New Mexico):New Mexico Geological Society, Guidebook 28,pp. 159-166.

Oil and Gas Journal, 1996, Worldwide FOR survey:Oil and Gas Journal, v. 94, no. 16, pp. 45-61.

Thompson, S., III, and Jacka, A. D., 1981,Pennsylvanian stratigraphy, petrography, andpetroleum geology of the Big Hatchet Peak sec-tion, Hidalgo County, New Mexico: New MexicoBureau of Mines and Mineral Resources, Circular176, 125 pp.

Woodward, L. A., Callender, J. F., Seager, W. R.,Chapin, C. E., Gries, J. C., Shaffer, W. L., andZilinski, R. E., 1978, Tectonic map of the RioGrande rift region in New Mexico, Chihuahua,and Texas; in Hawley, J. W. (compiler), Guide-book to Rio Grande rift in New Mexico andColorado: New Mexico Bureau of Mines andMineral Resources, Circular 163, sheet 2.