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  • Publicado : 17 de noviembre de 2010
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Lessons Learned
From Natural Gas STAR Partners
Executive Summary
In mature gas wells, the accumulation of fluids in the well can impede and sometimes halt gas production. Gas flow is maintained by removing accumulated fluids through the use of a beam pump or remedial treatments, such as swabbing, soaping, or venting the well to atmospheric pressure(referred to as “blowing down” the well). Fluid removal operations, particularly well blowdowns, may result in substantial methane emissions to the atmosphere. Installing a plunger lift system is a cost-effective alternative for removing liquids. Plunger lift systems have the additional benefit of increasing production, as well as significantly reducing methane emissions associated with blowdownoperations. A plunger lift uses gas pressure buildup in a well to lift a column of accumulated fluid out of the well. The plunger lift system helps to maintain gas production and may reduce the need for other remedial operations. Natural Gas STAR partners report significant economic benefits and methane emission reductions from installing plunger lift systems in gas wells. Companies have reportedannual gas savings averaging 600 thousand cubic feet (Mcf) per well by avoiding blowdowns. In addition, increased gas production following plunger lift installation has yielded total gas benefits of up to 18,250 Mcf per well, worth an estimated $127,750. Benefits from both increased gas production and emissions savings are well- and reservoir-specific and will vary considerably.

Method forReducing Methane Emmissons
Install a plunger lift system
1 2

Potential Gas Savings from Increased Gas Production and Avoided Emissions (Mcf/yr)
4,700 - 18,2502 per well

Value of Natural Gas Production and Savings ($)
$32,900 - 127,750

Cost of Implementation ($/well)
$2,591 - 10,363

Payback (months)
2 - 14

Value of gas $7.00/Mcf. Based on results reported by Natural Gas STARpartners.

This is one of a series of Lessons Learned Summaries developed by EPA in cooperation with the natural gas industry on superior applications of Natural Gas STAR Program Best Management Practices (BMPs) and Partner Reported Opportunities (PROs).

Technology Background

Liquid loading of the wellbore is often a serious problem in aging production wells. Operators commonly use beam liftpumps or remedial techniques, such as venting or “blowing down” the well to atmospheric pressure, to remove liquid buildup and restore well productivity. These techniques, however, result in gas losses. In the case of blowing down a well, the process must be repeated over time as fluids reaccumulate, resulting in additional methane emissions. Plunger lift systems are a cost-effective alternative toboth beam lifts and well blowdowns and can significantly reduce gas losses, eliminate or reduce the frequency of future well treatments, and improve well productivity. A plunger lift system is a form of intermittent gas lift that uses gas pressure buildup in the casing-tubing annulus to push a steel plunger, and the column of fluid ahead of it, up the well tubing to the surface. The plunger servesas a piston between the liquid and the gas, which minimizes liquid fallback, and as a scale and paraffin scraper. Exhibit 1 depicts a typical plunger lift system. The operation of a plunger lift system relies on the natural buildup of pressure in a gas well during the time that the well is shut-in (not producing). The well shut-in pressure must be sufficiently higher than the sales-line pressureto lift the plunger and liquid load to the surface. A valve mechanism, controlled by a microprocessor, regulates gas input to the casing and automates the process. The controller is normally powered by a solar recharged battery and can be a simple timer-cycle or have solid state memory and programmable functions based Exhibit 1: Plunger Lifts on process sensors. Operation of a typical plunger...
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