RESEARCH ARTICLE


Productivity Model for Shale Gas Reservoir with Comprehensive Consideration of Multi-mechanisms



Ya Deng1, Rui Guo1, Zhongyuan Tian1, Cong Xiao2, *, Haiying Han1, Wenhao Tan2
1 PetroChina Research Institute of Petroleum Exploration Development, Beijing 100083, China;
2 College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China


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© 2015 Xiao et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: * Address correspondence to this author at the College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China; Tel: 18810907235; E-mail: 987558984@qq.com


Abstract

Multi-stage fracturing horizontal well currently has been proved to be the most effective method to produce shale gas. This method can activate the natural fractures system defined as stimulated reservoir volume (SRV), the remaining region similarly is defined as un-stimulated reservoir volume (USRV). At present, no type curves have been developed for hydraulic fractured shale gas reservoirs in which the SRV zone has triple-porosity dual-depletion flow behavior and the USRV zone has double porosity flow behavior. In this paper, the SRV zone and USRV zone respectively are simplified as cubic triple-porosity and slab dual porosity media. We have established a new productivity model for multifractured horizontal well shale gas with Comprehensive consideration of desorption, diffusion, viscous flow, stress sensitivity and dual-depletion mechanism in matrix. The rate transient responses are inverted into real time space with stehfest numerical inversion algorithm. Type curves are plotted, and different flow regimes in shale gas reservoirs are identified. Effects of relevant parameters are analyzed as well. The whole flow period can be divided into 8 regimes: bilinear flow in SRV; pseudo elliptic flow; dual inter-porosity flow; transitional flow; linear flow in USRV; inter-porosity flow and boundary-dominated flow. The stress sensitivity basically has negative influence on the whole productivity period .The less the value of Langmuir volume and the lager the value of Langmuir pressure, the more lately the inter-porosity flow and boundary-dominated flow occurs. It in concluded that the USRV zone has positive influence on production and could not be ignored.

Keywords: Desorption, diffusion, dual inter-porosity, fractured horizontal well, productivity model, shale gas, SRV, stress sensitivity, type curve.