Investigation on Hydraulic Fracture Initiation and Propagation with LPG Fracturing in Shale Formation based on True Tri-Axial Laboratory Experiments
- Ruxin Zhang (State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, and State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum) | Bing Hou (State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, and State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum) | Yijin Zeng (State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Sinopec Research Institute of Petroleum Engineering) | Jian Zhou (State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Sinopec Research Institute of Petroleum Engineering) | Qingyang Li (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University)
- Document ID
- Society of Petroleum Engineers
- IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, 27-29 August, Bangkok, Thailand
- Publication Date
- Document Type
- Conference Paper
- 2018. IADC/SPE Asia Pacific Drilling Technology Conference
- 2.5.2 Fracturing Materials (Fluids, Proppant), 2 Well completion, 5.5 Reservoir Simulation, 3 Production and Well Operations, 5 Reservoir Desciption & Dynamics, 3 Production and Well Operations, 2.4 Hydraulic Fracturing
- Fracture Geometry, Engineering Factor, Laboratory Simulation Experiment, LPG Fracturing, AE Monitoring
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Traditional hydraulic fracturing requires lots of water and sand resulting in short fracture length and small SRV with a low production. However, a new waterless fracturing, called Liquefied Petroleum Gas (LPG) fracturing, is applied to stimulate shale formation effectively.
In order to figure out the mechanism of fracture initiation and propagation in LPG fracturing, four large-scale true tri-axial fracturing simulation experiments have been conducted on shale outcrops. Meanwhile, the effects of engineering factors, pump rate and fluid viscosity, on fracture propagation behavior in the shale formation are discussed.
The experimental results indicate that LPG fracturing not only activates discontinuities to form a complex fracture network, but also enhances induced fracture length to form a large SRV. Induced fractures have two initiation points, open-hole section and stress concentration point of wellbore wall, and have three main propagation behaviors, crossing, shear and arrest, dilation and crossing in shale formation. A low viscosity fracturing fluid activates discontinuities resulting in complex fractures, whereas, a high viscosity fluid would like to create some main fractures without opening discontinuities. Moreover, a high pump rate offers more energy for induced fractures to cross the discontinuities resulting in a long fracture length and large SRV. In addition, the anisotropic of shale formation and the existence of discontinuities cause signals attenuation, which increases the arrival time, resulting in location deviation of acoustic emission (AE) events in the AE monitoring. The pressure-time-energy curve, however, shows that the fracture initiation is earlier than the sample ruptured. That is, the initiation pressure is smaller than the ruptured pressure.
The experiments conducted in this paper prove that the LPG fracturing indeed has some advantages than traditional hydraulic fracturing, such as long fracture length and large SRV. And then, the research results provide the theoretical basis for the LPG fracturing operation in shale formation.
|File Size||2 MB||Number of Pages||14|
Fallahzadeh SH, James Cornwell A, Rasouli V, ., 2015. The Impacts of Fracturing Fluid Viscosity and Injection Rate on the Near Wellbore Hydraulic Fracture Propagation in Cased Perforated Wellbores. ARMA 15-645 presented at the 49th US Rock Mechanics / Geomechanics Symposium held in San Francisco, CA, USA, 28 June-1 July.