Abstract

Production from low-pressure gas wells was improved by widespread/extensive installation of well site compression in the Waddell Ranch Project. The Project was implemented in three phases over a period of three years beginning in June 2000. A total of 63 wells have been tested with well site compression; there are now 52 permanently installed compressors. The candidates were selected by testing the wells in the low-pressure area and additional wells highlighted by the Moving Domain study. Compressors were installed on successful test candidates in phases one and two. Phase three involved expanding the project to test the remaining 39 gas wells in the area by leasing compressors. This was done to reduce capital cost, take advantage of higher gas prices at the time, and gather data for proper design and sizing of the compressors.

Following studies were carried out as part of the project:

  1. Compare the response of wells in high-pressure area and low-pressure areas of the reservoir to wellhead compression.

  2. Feasibility study investigated the field wide compression by use of Central Compression System.

  3. This was followed by a study to determine the economics of well site compression versus central compression system.

  4. Financial study was carried out to determine the economics of leasing versus purchasing the well site compressors.

  5. The results and conclusion of project were:

    1. Reservoir technologies like Moving Domain study helped in candidate selection.

    2. The compressor project has been a success with an average initial uplift of 102 MCFD per well for 52 successful Judkins wells tested.

    3. Although the gas production increased significantly the decline rate has also increased indicating that we have accelerated gas production with some addition in reserves.

    4. Central Compression system with an estimated project cost of $12 million was found uneconomical.

    5. Individual well site compression was more economical method for gas production optimization. A total of $850,000 have been spent in three phases over 3 years.

Several operational improvements evolved which decreased downtime and cost of maintenance and enhanced the profitability of these installations. All these have been listed under the lessons learned part of the paper.

Introduction

Waddell Ranch Project is located in the Permian Basin in Crane County, Texas. It started production in the early 1930's and covers more than 1400 active wells in an area about 80,000 acres. The project includes 47 fields, which have produced over 400 million bbl of oil and 1.1 Tcf of gas. Six major fields account for 90% of the production from 12 zones ranging in depth from 2,800 to 10,600 feet. Most prolific of the zones are the Grayburg and San Andres that produce from depths between 2,800 feet and 3,400 feet.

CMC / IPM's performance as the operator has been excellent as illustrated by the project's exploration, exploitation, production, safety and maintenance records. Fig 1 below shows the gross oil and gas production from 1980 through 2003.

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