Stripper production is increasingly dependent on new technology.

Reacting to the energy bill debate in US Congress and the conflicts in the Middle East, a flurry of mainstream news reports on energy security issues has heightened (once again) the average American's appreciation of US dependency
on foreign energy supplies. Few people recognize, however, that the United States also "imports" 326 million bbl of its oil supply and 1.26 Tcf of its gas from another potentially precarious source: US stripper wells.
Stripper production, while not dependent on foreign policy or politics, is increasingly dependent on independent producers' access to new technology. Independents are largely responsible for operating US stripper wells.
According to the Interstate Oil and Gas Compact Commission, in 2000, 411,793 stripper oil wells in the United States produced an average of 2.16 b/d and 223,707 stripper gas wells produced an average of 15.4 Mcf/d. For these wells, often operating on the lower edge of profitability, production optimization can mean the difference between continued production and abandonment.
While many of these wells face region-specific problems with potentially simple solutions, smaller independent operators typically have neither the funds nor staff time to develop the new technologies (or variations on old technologies) needed to optimize production.
Recognizing this, in 2001 the US Department of Energy (DOE), through the National Energy Technology Laboratory (NELT), established the Stripper Well Consortium (SWC). As members of the SWC, operators pool their financial and human resources to economically develop these new technologies, with financial leverage from DOE.
SWC has more than 60 members from 14 states. Full membership status is reserved for companies and universities engaged in the US natural gas and petroleum industries. Dues are US $1,000 a year, and only full members are eligible to submit proposals. Details on the benefits of membership and the two dozen or so projects completed or under way are available at www.energy.psu.edu/swc.
DOE and the New York State Energy Research and Development Authority (NYSERDA) provide base funding for
the consortium. "The SWC solicits proposals for technology development projects from its members, and any proposed project requires a minimum of 30% cost share by the proposing organization. Elected members of the consortium select the projects to be funded on a year-by-year basis," Gary Covatch, DOE project manager responsible for SWC, said.
In 2001 SWC funded 13 of 23 proposed projects, committing $921,000. In March 2002 the SWC selected another 13 of 22 proposals, committing $1,338,374. "Ten of the projects selected in 2002 were new ideas, while three were projects that showed promise and were continued from the prior year," said Covatch. Several of the projects selected last year by this industry-driven collaborative effort have borne fruit.
For example, many shallow stripper gas wells that produce via smaller diameter casing require the periodic removal of water and oil that slowly build up in the wellbore. Techniques for doing this can be labor-intensive, pushing wells toward unprofitability.
In one of last year's SWC projects, Brandywine Energy and Development Co. developed the Gas Operated Automatic Lift (Goal) PetroPump for automatically lifting fluids from stripper gas wells. The pump is a unique, free-floating, automatically activated in-casing tool for the removal of downhole fluids using only in-well pressure. The tool is controlled by a preset pressure-sensing control valve within the tool that remains open when the tool is dropped into the casing, allowing it to descend. Upon reaching the desired depth within the fluid column, a sensor closes the valve and, coupled with the sealing cups surrounding the tool, creates a complete seal with the well casing. Downhole pressure subsequently builds behind the tool, eventually lifting the tool and fluid. Following delivery of the fluid to the surface and subsequent production of the gas, the tool valve automatically reopens, allowing the pump to descend for another cycle. According to the developer, the tool's completely automatic operation is primarily what differentiates it from standard casing plungers.
With cost-shared funding from SWC, the prototype pump was field-tested during the winter of 2001-2002 in two Medina sandstone gas wells in New York. It completed 15 to 20 cycles per month on average. Results showed a gas production increase of between 60% and 300% and the elimination of five well tender-assisted plunger runs a month. Additional tests are ongoing this summer in several non-Appalachian areas.
The standard pump is targeted to work in 4- or 5-in. ID casing with downhole pressures ranging from 100 psi to 600 psi. A fluid lift of 0.1 bbl to 3 bbl per cycle is typical. The wellhead must be modified to act as a tool lubricator and receiver, and the inside casing surface must be in good condition.
This sort of relatively low-tech approach to improving a well's performance by a few hundred million cubic feet per month may seem like small potatoes. But multiply that by a few thousand wells and things begin to add up. Production optimization is not just about boosting high-productivity well performance a few percentage points, but also about finding ways to maintain production from the low-productivity wells that have been and can remain reliable contributors to the nation's energy security.
More countries will face the problem of extending production from wells in maturing fields. The United States has mounted an aggressive campaign to develop technologies to keep marginal wells producing, and other countries may want to keep an eye on this model as they begin to face similar situations.
Companies interested in learning more about the Goal PetroPump or in joining SWC should contact Covatch at NELT's Strategic Center for Natural Gas, 304-285-4589 or gcovat@netl.doe.gov.

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