Figure 1. A decline curve shows current production rates and projected production and cash flow information. (Images courtesy of Compressco)
It’s no secret that the hottest natural gas play in the United States is the Barnett Shale in the Fort Worth Basin of North Central Texas. With more than 5,700 wells drilled to date and hundreds more in various stages of planning and completion, this is the place for natural gas operators.

Along with this opportunity have come a number of issues, including limited availability of drilling rigs, scarcity of downhole equipment, escalating costs and delays in the issuance of permits for pipeline construction. These issues have stymied many operators seeking to take advantage of this prolific field and, with natural gas prices still at relatively historic highs, they are looking for innovative ways to increase production to capitalize on the current positive market conditions.

Compressco, a subsidiary of TETRA Technologies Inc., is currently introducing an innovative approach for testing the production enhancement capabilities of a GasJack compressor on existing wells in the Barnett Shale. The Oklahoma City, Okla.-based company has been manufacturing and continually improving the GasJack unit for more than 15 years and has installed more than 3,000 units on marginally producing wells across the United States, Latin America and Canada.

GasJack technology
The GasJack compressor is an engineered wellhead compression and production tool designed to dramatically enhance the production and extend the economic life and recoverable reserves of mature or marginal gas wells. Marginal wells currently represent more than 64% of all domestic natural gas wells but account for less than 10% of total domestic production. With demand for natural gas outstripping domestic supply, technologies to enhance both the production and profitability from marginal wells have become increasingly necessary and sought-after.

The unit’s design makes it a cost-effective method of alleviating liquid loading by combining a vertical separator and blowcase to handle a wide range of suction and discharge pressures. Skid- or trailer-mounted, the compressor is easily moved from wellhead to wellhead with little or no required site preparation. Flexible hose connections make installation simple, and increased production often begins less than 2 hours after delivery of the unit. This allows operators to easily test candidate wells or move the unit from one marginal well to the next.

An excellent fit
In the last 3 years, dozens of these units have been set in the Barnett Shale area with outstanding results — dramatically increased production and significantly extended economic lives. The Jones #5 well in Denton County is an excellent example of a Barnett Shale mature gas well that has experienced the production enhancement achievable by implementing this technology.

The Jones #5 well was shut-in when a unit was installed in August of 2006. Figure 1 illustrates the current success of the implementation and the 5-year projected returns. The well is now producing at 175 Mcfd. The incremental reserves over the 5-year project life are 111 MMcf and, at current US $6 net market prices, the projected incremental cash flow from the well is $204,000 over the life of the project.

Figure 1 illustrates the current success of the implementation and the 5-year projected returns. The well is now producing at 175 Mcfd. The incremental reserves over the 5-year project life are 111 MMcf and, at current US $6 net market prices, the projected incremental cash flow from the well is $204,000 over the life of the project.

Figure 2. The “Hunt for a Million” test trailer features satellite telemetry equipment and AutoStart functionality.
‘Hunt for a Million’ program
Early last year, Compressco modified a number of GasJack units to create mobile testing units, kicking off a new program nicknamed “Hunt for a Million” (HFM). The HFM program was pilot-tested with a number of major operators in East and South Texas during the second half of 2006.

These operators accepted the challenge of using the GasJack compressor to find a minimum of 1 MMcf/d of incremental gas production from existing wells without the problems associated with having their own personnel implement and oversee GasJack viability testing. Through the HFM program, Compressco provides a complete turnkey test implementation on a candidate well — from delivery and set-up through disconnection and removal.

After successfully pilot-testing the HFM program, the company has recently launched the program in the Barnett Shale, with a large customer slated to begin HFM viability testing during the first quarter of 2007 and several other proposals under consideration.

The HFM mobile test units combine satellite telemetry with a proven package design to test the viability of candidate wells before permanently setting a unit on any given well (Figure 2). The ePumper satellite system allows the unit to be polled continuously over the Internet by either the operator or Compressco personnel. The online availability provides real-time test results without manpower, logistics or safety concerns.

Prior to beginning HFM testing, engineers work to identify candidate wells. Such wells are chosen for classic signs of liquid loading, elevated line pressures, erratic production rates, distance from central compression stations and tubing size in relation to minimum volumes needed to maintain critical velocity.

Many high-tech features have been included on these specialized HFM test units. They include:

• TOTALFLOW telemetry system, used for collecting critical data such as pressure, Btus, temperature, well specs, and historic and current flow volumes.
• GasJack ePumper and AMCI’s SatAlarm systems, allowing for digital satellite data transmission from the field to the home office, eliminating the need for field personnel to be on site to collect this data. GasJack units are also tracked via GPS to verify where and on which well they are set.
• Compressco’s AutoStart system, which may be used in conjunction with plunger lift systems, tubing jets or intermitters to provide automatic start-up or shut-down of the unit in applications where irregular fluid volumes occur, once again eliminating the need for on-site field personnel.

Over the last 6 months, eight HFM test units were rotated to 32 wells, netting a total increase in gas production in excess of 1 MMcfd. Sixteen of these wells now have permanent (non-HFM) units in place, and their combined production easily surpasses the original goal of the testing program with additional testing an ongoing process.

The benefit of implementing HFM viability testing is that, for a minimal weekly cost, Compressco personnel take care of everything — from delivery and set-up through disconnection and removal. An operator can establish a threshold whereby, if a certain production rate is reached during an HFM test, a standard unit will automatically be installed on the well. Based on the initial success of the HFM program, Compressco plans to almost triple the number of HFM units in its fleet to meet the growing demand for HFM viability testing.

The value proposition of utilizing viability testing such as that available in the HFM program is that operators can more clearly see the hidden value in their existing marginally producing properties. With this low-cost solution, production rates can be increased while allowing operators to identify and quickly begin to benefit from the upside potential of their properties.