The tough-to-drill yet prolific Cotton Valley trend of east Texas and northwest Louisiana doesn’t give up its prize easily, but Goodrich Petroleum has drilled 175 wells there with a 99.5% success rate (Figure 1). With 110,000 acres under lease, nine rigs working full-time and a near-perfect record, one might wonder what else can be improved? The answer is efficiency.
Multizone treatment saves time
Most Cotton Valley and Travis Peak wells need a little help in the form of hydraulic fracturing
Figure 1. The Cotton Valley trend spans East Texas and Northwest Louisiana and is currently a center of drilling and completion activity. (Images courtesy of Schlumberger) |
The traditional process for completing these wells involved four steps: perforate an interval, stimulate it, flow the zone overnight to clean it up and then set a composite bridge plug to protect the zone so the next shallower zone could be treated. After treating all zones, a coiled tubing (CT) unit would be mobilized to drill out the plugs to enable flowback and final completion. Typically, the process would take 5 days and cost more than US $250,000. Although the traditional plan worked, it consisted of essentially the same steps repeated over and over. Usually when processes are repetitious, ways can be found to make them more efficient.
Completion time and money
The company considered alternative procedures to see if completion time and cost could be
Figure 2. The PerfFRAC service sequence is shown. Four zones were perforated and treated in a single wireline run. |
Due to the reservoir conditions in the fields under development, the combined technology made the most sense. The choice was based on having the ability to complete each well with a single wireline trip. No composite bridge plugs were required, and no CT unit was needed. Specific benefits of the chosen technique identified included:
• Reduced costs of multizone stimulations;
• Effective isolation of each zone;
• Point source fracturing of each zone;
• Elimination of plug setting and drilling-out time;
• Compatibility of completion fluid and formation; and
• Commencement of clean-up within 24 hours.
An elegant solution
To perforate and treat a well using the combined perforating and fracture technique requires
Figure 3. The completion technique compares well vs. traditional completion techniques used in offset wells. PerfFRAC enhancements are designed to refine and optimize the technique for each specific application. |
A study comparing the productivity from a well completed using the PerfFRAC technique with two similar offset wells showed significant improvement in cumulative production (Figure 3). In addition, Goodrich Petroleum experienced a 50% decrease in completion time and a 25% decrease in completion costs on the first eight wells treated in the Cotton Valley, Travis Peak and Hosston formations.
Enhancements add value
The use of selective perforating with high-performance guns and perforating techniques
Figure 4. Timeline of completion process using conventional approach versus PerfFRAC. |
The PerfFRAC technique is a part of contact staged fracturing and completions services designed to maximize reservoir contact by offering the most efficient and effective stimulation for each well. It comes with a planning workflow that helps prospective users determine its
applicability for the specific well or reservoir they are targeting and predict with some accuracy the expected result.
In the example given, Goodrich was able to take advantage of a selection of enhancements to the basic procedure to customize the perforation and treatment package to its specific situation and needs. The planning stage allows each enhancement to be evaluated on its own merits and also as part of the collective result of a customized package. The company plans to continue using the technique while developing and evaluating further enhancements.
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