Abstract

The combination of reservoir modeling, a revised characterization of the reservoir, the incorporation of horizontal drilling technology, followed by an economical program of deepening vertical wells to a deeper, very low pressure reservoir has resulted in a highly viable reserve acceleration program at the Puckett Ellenburger Field.

The Puckett Ellenburger Field is a mature, dry gas, depletion drive reservoir, located in the deep Delaware Basin of west Texas. Cumulative production is 3.55 TCF of the estimated 3.77 TCF OGIP. Reservoir pressure has declined from an original pressure of 6,675 psia to a current pressure of ~ 400 psia in the field’s 48-year history. Reservoir depth ranges from 12,000’ to 15,000’. Until recently, the reservoir was considered fully developed and on a slow, steady decline, with minimal well work activity. The field has 34 active wells operated by four companies. Chevron is the second largest operator in the field with a total of 14 wells.

In early 1997, Chevron performed a reservoir modeling study to understand the effect of our competitor’s accelerated production on Chevron’s reserve base. The study resulted in the initiation of our own reserve recovery and acceleration project. This aggressive project began in late 1997, and included the removal of production tubulars in one well, horizontal recompletion of two vertical wells, vertical deepening of seven wells, and the installation of centralized compression.

Utilizing fracture orientation data from FMI logs and later a reservoir model which targeted the key productive interval within this 1600’ thick reservoir, Chevron’s program proved to be most successful in the cost-effective increase in production and acceleration of reserve recovery. Chevron’s operated production increased from 28 MMCFPD to 102 MMCFPD. Most, if not all, of this incremental production was realized without the benefit of central compression. Chevron’s individual well production increases ranged from 3 to 13 fold. Superior project performance can be attributed to several factors including, a more thorough geologic and engineering understanding of the production characteristics of this reservoir, better drilling techniques in this challenging reservoir environment, and a superior stimulation procedure incorporating new downhole phase separator technology.