Evaluation of Stimulation Techniques Using Microseismic Mapping in the Eagle Ford Shale
- Abhijeet Ashok Inamdar (Schlumberger) | Tolulope Mobereola Ogundare (St. Mary Land & Exploration Co) | Raj Malpani (Schlumberger) | William Keith Atwood (Schlumberger) | Keith Brook (Schlumberger) | Abdunnaser M. Erwemi (Schlumberger) | Dave Purcell (SM-Energy)
- Document ID
- Society of Petroleum Engineers
- Tight Gas Completions Conference, 2-3 November, San Antonio, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2010. Society of Petroleum Engineers
- 3 Production and Well Operations, 3.3.1 Production Logging, 4.1.2 Separation and Treating, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.8.2 Shale Gas, 2.2.2 Perforating, 5.6.9 Production Forecasting, 2.5.1 Fracture design and containment, 5.8.4 Shale Oil, 2.5.2 Fracturing Materials (Fluids, Proppant), 4.6 Natural Gas
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The main goal in stimulating shale formations is to maximize the reservoir contact with the hydraulic fracture face. In order to achieve this goal current practices include pumping low-viscosity fluids at high rates with small mesh proppant cycles. A novel approach was used in a well in the Eagle Ford shale to enhance the stimulated area. This technique, called "relax-a-frac", was developed by an operator/service company alliance during the exploration phase. Real-time microseismic hydraulic fracture monitoring (RT HFM) indicated that the conventional slickwater treatments were not providing adequate lateral coverage across the planned stage. To address this issue, controlled changes were made to the pumping schedule, and the effects were evaluated using RT HFM. The results indicated that relax-a-frac proved to be highly successful in increasing the estimated stimulated volume (ESV) in this formation and area.
In relax-a-frac, a part of the stimulation treatment was pumped (usually pad plus proppant slugs), followed by an extended shutdown to relax the formation. Once the surface pressure reached a predetermined value, the treatment was resumed, as per program, with monitoring for microseismic activity. The microseismic activity observed during the second part of the treatment showed a significant increase compared to that of the first part, with improved lateral coverage. The resultant ESV increased significantly from this technique as compared to any other specific changes tried on these wells. Production log results from Well 1 showed a definitive correlation between production contribution and the ESV derived from HFM analysis. This paper documents that this novel approach more effectively stimulates the Eagle Ford shale when compared to the typical treatment designs. Conclusions from a detailed comparison of the well performance and its relation to the treatment design are included.
Key reservoir parameters that must be studied to evaluate the potential of any shale well are; thermal maturity, adjacent water-bearing formations, mineralogy, faults, fractures, organic richness, effective porosity, matrix permeability, and thickness. Key engineering parameters are: penetration rate, lateral landing point, fluid compatibility, fracture containment, fracture orientation, presence of natural fractures, fracture complexity, and retained fracture conductivity. The relative importance of the engineering parameters varies with the shale play.
Hydraulic fracture complexity is the key to unlocking the potential of shale plays. Microseismic monitoring suggests that complex fracture network can be developed in some shale plays. Microseismic monitoring is a proven technology and has been widely used to monitor and evaluate the effectiveness of hydraulic fracture treatments in various formations, including shale. Theoretically, in shale plays, a complex fracture should produce better compared to bi-wing planer fractures as a result of increased fracture surface area.
This paper outlines the integration of engineering and reservoir parameters with microseismic monitoring to optimize stimulation design.
|File Size||2 MB||Number of Pages||10|