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Abstract: Design, Implementation, and Completion of a Horizontal Tight Gas Wellbore - Case Study: Green River Basin, Wyoming

Randal L. Billingsley, Lesley W. Evans, Timothy M. Anderson, Ronald E. Lengerich

In September, 1993 Amoco Production Company began drilling the Champlin 254B #2H, a horizontal well test located near the Wamsutter Arch, southwestern Wyoming. The Champlin 254B #2H was designed to confirm a fractured reservoir concept and to test the economic viability of a horizontal wellbore in the Almond formation.

The wellbore was designed to determine real-time, the fracture direction and the optimum horizontal leg direction within the confines of the drilling permit. A deviated pilot hole was drilled to optimize our ability to cross vertical natural fractures. MWD gamma-ray, oriented core, a vertical seismic profile, Formation Microimager, and a robust suite of electric logs were obtained to gain information on the presence and orientation of fractures before kickoff for the horizontal leg. Electromagnetic goniometry was used onsite to orient fractures in core. Log and core data were consistent and a wellbore trajectory of due South was chosen.

A two thousand foot horizontal wellbore was drilled, 1700 feet of which is in the upper Almond formation productive zone. MWD gamma-ray, three 30^prime cores, Formation Microscanner logs, and a density-neutron log were obtained in the horizontal hole. This wellbore was completed open-hole with a stabilized gas rate of 1 mmcfd.

In May, 1994 a portion of the original wellbore collapsed and a replacement horizontal leg was drilled. Oil-based mud and rotary BOP's were utilized to minimize damage and invasion to the reservoir. Reservoir pressures encountered in the redrill indicate that depletion along the original wellbore had begun. The redrill was completed open-hole with a pre-perforated (every third joint) 5 1/2^Prime liner and also stabilized at a rate of 1 mmcfd.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada