The goal is to improve the economics of marginal gas wells in order to maintain production and maximize recovery of domestic gas resources.
Schlumberger Data and Consulting Services (previously Holditch - Reservoir Technologies) – Project management and all research products
Belden & Blake
Great Lakes Energy Partners
Pittsburgh, PA 15275-1011
Field test – Western PA
The objective is to develop a method for operators to easily and rapidly recognize stripper gas wells that are performing below their expected potential relative to offset wells within a particular geographic area. This would allow for optimal prioritization of wells for remedial stimulation or rework.
The approach in this project was to assume that general, localized production trends exist within a field, and that any abrupt change exhibited by an individual well relative to an established trend in its vicinity can be used to identify that well as a potential remediation candidate requiring additional study. A software product was then developed to perform this comparison and display the results. Field tests of the product, using actual data from stripper well operators, were then carried out.
Stripper gas well operators frequently find it difficult to identify marginal or under-performing wells within producing areas. The primary challenge is the magnitude of the data that must be reviewed and the limited resources for doing so. These operators need an easier and faster way to screen stripper wells and identify candidates in need of remediation. The software developed in this project will provide the operator with a tool to quickly identify the underperforming wells in an area, thereby allowing the operator to prioritize remedial stimulation or repairs to those wells requiring attention. This in turn will help to keep marginal wells operating, maximizing overall production.
The PC-based program developed under this project, Stripper Well Analysis Remediation Methodology (SWARM), utilizes cumulative production and normalized production rates (average monthly production for a desired year) as “indicators” or short-term gauges to assist in predicting long-term performance. Each of these indicators is related to date of first production (DOFP) and plots of “x-year” Cumulative Production vs. DOFP and/or Normalized Production Rate vs. DOFP, and are generated using input production data. The software generates indicators for every well within a field, and then compares each well with each offset within its “domain” (specified radius of investigation). The user chooses a target percentage of the production indicator (PI) of the wells in a given domain that a target well’s PI must fall below in order to be recognized as a low-performer (e.g., 50 percent). The entire well list is processed and all qualifying target wells that meet the chosen criteria are listed. This provides a rapid, efficient, and automated method to identify wells that are underperformers and that may have potential for production enhancement. Although the primary objective of the program is to screen for underperformers, it is important to note that SWARM can also distinguish “overperformers,” by selecting a user-defined percentage of 125 percent or 150 percent.
After this phase is completed, a review of each selected candidate well’s completion data, geologic information, production history, and operating environment should be conducted to determine the most likely cause for its relatively poorer performance. The appropriate remediation treatment can then be recommended, based on the economics of the situation.
SWARM was beta-tested with data from approximately 729 stripper wells in a gas field located in northwestern Pennsylvania, operated by Great Lakes Energy Partners, LLC (Great Lakes) and Belden & Blake Corporation (B&B). SWARM identified 41 wells that performed significantly lower than their offsets and warranted additional review. Eight of these underperformers are operated by Great Lakes and 33 by B&B. However, for reasons unbeknownst to Schlumberger, none of these wells were considered for rework by the operators.
Great Lakes also provided information for more than 2,000 additional wells located in northwestern Pennsylvania in their Cooperstown field. In this field, the SWARM software identified two hundred twenty-two (222) candidates, of which 26 have been reworked to date. 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 remediations.
The project is complete.