Impact of Asymmetric Stimulated Rock Volume on Casing Deformation in Multi-Stage Fracturing; A Case Study
- Hao Yu (Southwest Petroleum University, China) | Arash Dahi Taleghani (Pennsylvania State University, United States) | Zhanghua Lian (Southwest Petroleum University, China) | Tiejun Lin (Southwest Petroleum University, China)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 30 September - 2 October, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2019. Society of Petroleum Engineers
- Stress re-Distribution, Multi-stage Fracturing, Asymmetric Fractures, Casing Deformation, Microseismic Data
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Microseismic data and production logs in our study area have confirmed an asymmetric development of the stimulation rock volume, while severe casing deformation problems have been reported frequently in this area. In this paper, we investigate the possibility of casing failure due to strong shear stresses developed by asymmetric stimulated zones. Overlapping stimulation zones in adjacent stages may intensify asymmetry of the pore pressure distribution and resultant shear forces. Although induced shearing may have a positive impact on fracture permeability, but it may also cause operational problems by inducing severe casing deformations. While most of the casing deformation models only consider rock deformations very close to the wellbore, we developed a 3D coupled model for fracture network growth and stress re-distribution during hydraulic fracturing to achieve a more realistic model for casing deformation. This reservoir-scale model is tied to a more detailed near-wellbore model including the casing and cement sheath to simulate casing deformations. Case studies were conducted using data from a shale gas well that experienced severe casing deformation during hydraulic fracturing. Impact of stage spacing, and pumping rate are incorporated to investigate their potential impacts on casing and well integrity. Multi-stage hydraulic fracturing considering the development of complex fracture network is simulated at the reservoir scale based on the microseismic events. Continuous re-distribution and re-orientation of stress field near the borehole are tracked during the development of the fracture network which reveals some pocket of tensile stresses along the casing. Asymmetric fractures are observed to generate strong shear stress on the suspended casing. These shear forces result in deflection and S-shape deformations. Some regions receive repeating treatments, which leads to increase formation stress heterogeneity and worsen casing deformation severity. Our analysis has indicated that simply increasing the flexural strength by increasing thickness of casing cannot radically mitigate casing deformation problems. This paper provides a novel workflow for a coupled modelling of casing deformation during hydraulic fracturing operations, while current modelling efforts assume symmetric fracture geometries.
|File Size||2 MB||Number of Pages||17|
Lin, R., Ren, L., Zhao, J., and Huang, J., 2017. Stimulated Reservoir Volume of Multi-Stage Fracturing in Horizontal Shale Gas Well: Modeling and Application. SPE-186294-MS, presented in SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition held in Jakarta, Indonesia. Society of Petroleum Engineers.
Zhao, C., Li, J., Liu, G., Zhang, H., Wang, C., Ren, K., and Zhang, X., 2018. The Casing Deformation during Shale Gas Hydraulic Fracturing: Why it is so serious in Weiyuan-Changning, China? SPE-191273-MS, presented in SPE Trinidad and Tobago Section Energy Resources Conference held in Port of Spain, Trinidad and Tobago. Society of Petroleum Engineers.