Abstract

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 Mississippian ranges from 5,500 ft in the northwest to 16,850 ft in the southeast. Lower Mississippian (Kinderhookian and Osagian) strata are 0 to 800 ft thick and are comprised of marine limestones and minor shales and chert. Upper Mississippian (Meramecian and Chesterian) strata are 0 to 1600 ft thick and are comprised of shallow marine limestones and shales. Within the Upper Mississippian section, there is a sharp transition from shelf deposits dominated by limestones in the north and the basinal Barnett Shale in the south. Stratigraphic analyses indicate a Mississippian ancestry for the Tatum Basin and for the Lower Permian shelf-basin boundary.

Forty gas and oil pools have been productive from Mississippian reservoirs in Eddy, Lea, and southern Chaves Counties. Twenty-four pools have been productive from Upper Mississippian reservoirs and 12 have been productive from Lower Mississippian reservoirs. Four gas pools have been productive from both Upper and Lower Mississippian reservoirs. The Mississippian play is one of the smallest plays in southeastern New Mexico and has yielded a cumulative 28 BCF gas and 1.3 MMBO from the 40 pools in Eddy, Lea, and southern Chaves Counties. Most production has been obtained from Chesterian limestone reservoirs of the northern shelf. Chesterian reservoirs are concentrated in the structurally low Tatum Basin where uppermost Chesterian strata were preserved prior to deposition of Early Pennsylvanian sediments.

Four subplays are identified in the Mississippian of Eddy, Lea, and southern Chaves Counties of southeastern New Mexico: (1) Chester shallow marine limestones in the Tatum Basin on the northern shelf; (2) Upper Mississippian 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 untried Barnett Shale in the southern basin.