Resolving Created, Propped and Effective Hydraulic Fracture Length
- Craig L. Cipolla (Pinnacle Technologies) | Elyezer Lolon (Pinnacle Technologies) | Michael J. Mayerhofer (Pinnacle Technologies)
- Document ID
- International Petroleum Technology Conference
- International Petroleum Technology Conference, 3-5 December, Kuala Lumpur, Malaysia
- Publication Date
- Document Type
- Conference Paper
- 2008. International Petroleum Technology Conference
- 5.8.2 Shale Gas, 4.1.2 Separation and Treating, 5.3.2 Multiphase Flow, 4.6 Natural Gas, 5.6.5 Tracers, 2.2.2 Perforating, 1.6 Drilling Operations, 5.8.1 Tight Gas, 3 Production and Well Operations, 5.1.5 Geologic Modeling, 3.3 Well & Reservoir Surveillance and Monitoring, 5.6.4 Drillstem/Well Testing, 2.5.2 Fracturing Materials (Fluids, Proppant), 2.4.3 Sand/Solids Control, 5.5.8 History Matching, 5.5 Reservoir Simulation, 5.6.3 Pressure Transient Testing, 5.1 Reservoir Characterisation, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation
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Recent advances in hydraulic fracture mapping technologies have provided a wealth of information on the created fracture length in numerous geologic settings. Prior to such measurements, fracture length was estimated using "un-calibrated" fracture propagation models--but there was significant uncertainty in the results that cascaded into subsequent production analyses. However, we also need to understand how the created fracture length relates to the location of proppant in the fracture and the producing or effective length to evaluate well performance and improve stimulation designs. Unfortunately, the advanced fracture mapping technologies that today provide accurate measurements of the created fracture length cannot provide any insights (yet) into the propped and effective fracture lengths. Advanced production data analyses, pressure transient testing, and/or numerical reservoir modeling are required to determine the effective fracture length.
This paper begins with a comparison of the strengths, weaknesses, and limitations of fracture modeling, production data analysis (PDA), pressure transient analysis (PTA), and numerical reservoir modeling to estimate effective fracture length and conductivity. This work also evaluates how the complexities (in the hydraulic fracture) associated with non-Darcy flow, multi-phase flow, and complex fracture geometries affect the results from the various techniques. This work documents the significant differences in "effective" fracture length that, in many cases, can result from each technique and how these uncertainties can impact fracture treatment designs and field development decisions.
The paper concludes with several field case histories that illustrate the integration of multiple technologies to determine the created, propped, and effective fracture length, including direct measurements of created fracture length from microseismic fracture mapping. The case histories illustrate the dramatic differences in created and effective fracture length that can occur in some reservoirs, while also showing that in some cases effective fracture lengths can be very similar to the created length (and quite long).
Reliable estimates of fracture length (i.e., that is created, propped, and producing or effective) are necessary to consider design changes in subsequent fracture treatments in order to optimize the performance of hydraulically fractured wells particularly in low permeability reservoirs. The created fracture length is the fracture length propagated during the fracture treatment, while the propped fracture length is the length supported by proppant after the fracture closes. The effective or producing length (the more important fracture length compared to the created and propped length) is the length that is open or contributing to hydrocarbon production after a fracture treatment. That is, increasing the effective fracture length usually means increased production.
|File Size||1 MB||Number of Pages||15|