A Rapid and Efficient Method To Identify Underperforming Stripper Gas and Oil Wells
Authors: MacDonald R. J. , Frantz J. H. , Covatch G. , Zagorski W. , Forgione M. 
Published: December 2007

Stripper gas and oil well operators frequently face a dilemma regarding maximizing production from low-productivity wells. With thousands of stripper wells in the United States covering extensive acreage, it is difficult to identify easily and efficiently marginal or underperforming wells. In addition, the magnitude of reviewing vast amounts of data places a strain on an operator's work force and financial resources.

Schlumberger DCS, in cooperation with the National Energy Technology Laboratory (NETL) and the U.S. Department of Energy (DOE), has created software and developed in-house analysis methods to identify remediation potential in stripper wells relatively easily. This software is referred to as Stripper Well Analysis Remediation Methodology (SWARM).

SWARM was beta-tested with data pertaining to two gas fields located in northwestern Pennsylvania and had notable results. Great Lakes Energy Partners, LLC (Great Lakes) and Belden & Blake Corporation (B&B) both operate wells in the first field studied. They provided data for 729 wells, and we estimated that 41 wells were candidates for remediation. However, for reasons unbeknownst to Schlumberger these wells were not budgeted for rework by the operators.

The second field (Cooperstown) is located in Crawford, Venango, and Warren counties, Pa and has more than 2,200 wells operated by Great Lakes. This paper discusses in depth the successful results of a candidate recognition study of this area.

We compared each well's historical production with that of its offsets and identified 339 underperformers before considering remediation costs, and 168 economically viable candidates based on restimulation costs = $50,000 per well. From this data, we prioritized a list based on the expected incremental recoverable gas and 10% discounted net present value (NPV). For this study, we calculated the incremental gas by subtracting the volumes forecasted after remediation from the production projected at its current configuration.

Assuming that remediation efforts increased production from the 168 marginal wells to the average of their respective offsets, approximately 6.4 Bscf of gross incremental gas with a NPV approximating $4.9 million after investment, would be made available to the domestic market.

Seventeen wells have successfully been restimulated to date and have already obtained significant production increases. At the time of this report, eight of these wells had enough post-rework production data available to forecast the incremental gas and verify the project's success. This incremental gas is estimated at 615 MMscf. The outcome of the other ten wells will be determined after more post-refrac production data becomes available. Plans are currently underway for continued future restimulations.

The success of this project has shown the value of this methodology to recognize underperforming wells quickly and efficiently in fields containing hundreds or thousands of wells. This contributes considerably to corporate net income and domestic natural gas and/or oil reserves.