Streamlined Completions Process: An Eagle Ford Shale Case History
- Andrew Lee Arguijo (Cabot Oil & Gas Corp.) | Lee S. Morford (Triton Engineering Services Co) | Jason Baihly (Schlumberger) | Isaac Aviles (Schlumberger)
- Document ID
- Society of Petroleum Engineers
- SPE Canadian Unconventional Resources Conference, 30 October-1 November, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 1.6.6 Directional Drilling, 2 Well Completion, 1.6 Drilling Operations, 5.8.4 Shale Oil, 2.5.4 Multistage Fracturing, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 4.6 Natural Gas, 3 Production and Well Operations, 1.10 Drilling Equipment, 4.3.4 Scale, 1.2 Wellbore Design, 6.6.2 Environmental and Social Impact Assessments, 4.1.2 Separation and Treating, 5.8.2 Shale Gas, 2.2.2 Perforating, 2.5.2 Fracturing Materials (Fluids, Proppant), 1.14 Casing and Cementing
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The Eagle Ford shale is a hydrocarbon-producing formation of significant importance due to its capability for producing at high-liquid/gas ratios, more so than other traditional shale plays. Situated in south Texas, the total Eagle Ford liquids production in 2007 was less than 21,000 bbl total. In 2011, production averaged 65,500 BOPD in the play (EIA, 2011). Activity in the Eagle Ford continues to increase because the benefits from producing high liquid yields across much of the play, along with attractive commodity prices, have made the Eagle Ford a more attractive development over many other shale reservoirs.
The rapid development of the Eagle Ford shale was enabled by horizontal drilling. In 2007 none of the reported production was from horizontal wells. In 2011 alone over 2,800 drilling permits were issued, virtually all of them for horizontal wells (RigData, 2012). The Eagle Ford shale has low-clay content, high-carbonate content, and is in an extensional basin, making it conducive to somewhat complex hydraulic fracturing (Martin et al, 2011). The plug and perforating technique has become the preferred completion method in the play due to multiple entry points creating complex fractures at a minimal cost. This completion technique requires a mechanical means for conveying perforating guns, such as coiled tubing (CT), wireline tractor or stick pipe, for the first fracturing stage at the toe of the well.
To streamline their completion process, an Eagle Ford operator chose to use an initiator valve that is run at the toe of the well as part of the final completion design. This pressure activated valve is capable of initiating operations on the first fracturing stage without the need for CT or other mechanical means of conveyance of perforating guns. Simple and robust, the valve is activated by a pressure increase from the surface. The valve uses a rupture disc for precise activation and a helical port design that allows for hydraulic fracturing to be performed through the valve into the cement and the formation. With over a dozen wells completed in the Eagle Ford formation by the operator, the valve has provided logistical and economic benefits to the streamlined completion process.
This paper describes the initiator valve completion tool and its application in the Eagle Ford shale. A case history is presented to show the specific design and operation of the initiator valve, as well as its benefits over other completion practices that target the first stage in a closed lateral system. Detailed activation of the valve and fracturing data through the valve are also presented.
Tight economics in many onshore North American unconventional oil and gas plays has made it important for operators in such reservoirs to maximize economics as much as possible. One way to aid in maximizing the economics is through the use of improved drilling and completion techniques and cost control; one such method is to eliminate interventions during the well completion process. Every time a tool is run in the hole, the total cost of the well increases. One costly intervention that can be eliminated is the initial perforating run on the first stage of a cemented lateral well. During this operation, the well is a closed system which prevents the plug and gun assembly from being pumped to the toe of the lateral. To address this inefficiency a costly, timely, and in some cases risky CT, stick pipe, or wireline tractor run must be used to convey the guns into the lateral which is a closed system. A novel valve was developed to initiate the fracturing process in horizontal cemented wells. The process eliminates the intervention historically used to perforate the first stage. The initiator valve is a pressure-activated valve installed as part of the casing string placed at the toe stage of the well. The valve, cemented in place and requiring no changes to the cement operation or chemistry, is pressure activated and once the sliding sleeve in the valve is opened, the wellbore fluid is exposed to the cement sheath in the annular space. At this point the fracturing operation can begin. Once the first stage is complete, lower cost pump down plug and perf operations can begin.
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