Underdeveloped oil fields in Upper Pennsylvanian and Lower Permian carbonates of southeast New Mexico: initial development missed major reserves

(from the introduction to the paper)

Ronald F. Broadhead

New Mexico Bureau of Mines and Mineral Resources,

A Division of New Mexico Tech

Socorro, NM

Carbonate reservoirs of Upper Pennsylvanian and Lower Permian age are significant reservoirs for oil and gas in southeast New Mexico . The approximately 400 Upper Pennsylvanian and Lower Permian carbonate reservoirs have produced a cumulative 508 million bbls oil (MMBO) and 3.2 trillion ft3 gas (TCFG). This is 12 percent of the oil and 16 percent of the gas produced in southeast New Mexico.

Sixteen of these 400 fields have been identified as being underdeveloped at some stage in their history. At the beginning of 1998, these ranged in size from tiny Milnesand West with a cumulative production of 296 thousand bbls oil (MBO) to huge Dagger Draw with a cumulative production of 55 MMBO.

An underdeveloped field can be defined as an oil or gas field that was incompletely developed subsequent to initial field discovery. Underdeveloped fields typically produce minimal levels of oil and gas from only a few wells drilled in the period immediately following field discovery. One or more subsequent discrete phases of redevelopment several years, even decades, after field discovery reinvigorate production. These phases of redevelopment do not involve infill drilling nor do they involve secondary or tertiary recovery techniques. Rather, they are based upon drilling the same pay zone that was produced during initial development of the field but from proration units that remained undrilled during initial development. As such, they represent new oil that was unrecognized at the time of field discovery and initial development. For the 16 identified underdeveloped fields, redevelopment has accounted for 65% of developed reserves and initial development has accounted for only 35% of developed reserves (Table 1).

Field Discoveryyear Redevelopment year(s)

Cumulative oil production,

12/31/97, MMBO

Percent reserves from initial development Percent reserves from 1st redevelopment Percent reserves from 2nd redevelopment
Allison 1954 1959 23.7 10% 90% NA

Anderson

Ranch

1953 1958, 1984 4.2 48% 38% 14%
Baum 1955 1968, 1980 12.9 1% 59% 39%
Bough 1949 1966 6.3 71% 29% NA
Cerca 1968 1972, 1979 0.3 10% 43% 48%
Cuerno Largo 1971 1990 0.7 29% 71% NA
Dagger Draw 1965 1988 55.6 <5% >95% NA
Four Lakes 1956 1991 2.7 71% 29% NA
Hightower East 1950 1980 1.0 8% 33% 59%
Lazy J 1952 1982 7.5 75% 25% NA
Milnesand West 1968 1983 0.3 9% 91% NA
Morton 1964 1980 2.6 60% 40% NA
Morton East 1970 1986 1.7 84% 16% NA
Saunders 1950 1957, 1980 38.6 68% 8% 23%
Tulk 1951 1969, 1983 2.4 65% 23% 12%
Young North 1989 1991 0.9 10% 90% NA