Mississippian strata of southeastern New Mexico: distribution, structure, and hydrocarbon plays

Mississippian strata of southeastern New Mexico are Kinderhookian to Chesterian in age. In Eddy, Lea, and southern Chaves Counties, depth to the top of the Mississip- pian ranges from 5,500 ft in the northwest to 17,000 ft in the southeast. Lower Mississip- pian (Kinderhookian and Osagian) strata are 0-800 ft thick and comprise marine limestones and minor shales and chert. Upper Mississip- pian (Meramecian and Chesterian) strata are 0-600 ft thick and comprise shallow marine limestones and shales. Within the Upper Mis- sissippian section there is a sharp transition from shelf deposits dominated by limestones in the north to the basinal Barnett Shale in the south. Stratigraphic analyses suggest a Missis- sippian ancestry for the Tatum Basin and for the Lower Permian shelf-basin boundary. Forty-five gas and oil pools have been productive from Mississippian reservoirs in Eddy, Lea, and southern Chaves Counties. Twenty-seven pools have been productive from Upper Mississippian reservoirs, and 14 have been productive from Lower Missis- sippian reservoirs. Four gas pools have been productive from both Upper and Lower Mis- sissippian reservoirs. The Mississippian play is one of the least developed plays in south- eastern New Mexico and has yielded a cumu- lative 46 billion ft3 (BCF) gas and 1.4 million bbls oil and condensate (MMBO) from the 45 pools in Eddy, Lea, and southern Chaves Counties. Most production has been obtained from Chesterian limestone reservoirs of the northern shelf. Chesterian reservoirs have been developed in the paleostructurally low Tatum Basin where uppermost Chesterian strata were preserved before deposition of Early Pennsylvanian sediments. Four subplays are identified in the Mississip- pian of Eddy, Lea, and southern Chaves Coun- ties of southeastern New Mexico: (1) Chester shallow marine limestones in the Tatum Basin on the northern shelf; (2) Upper Mississip- pian limestones interbedded with Barnett shales just south of the shelf-basin transition; (3) small and widely disseminated reservoirs in lower Mississippian limestones in the north; and (4) the as-yet untested Barnett Shale in the southern basin.