Title: A modified exponential decline method for shale gas reservoirs

Authors: Shaolei Wei; Xuebin Huang; Jun Li; Yinghong Su; Quanjie Lu; Wenjun Huang

Addresses: Sinopec Petroleum Exploration and Production Research Institute, Olympic Building, No. 267, 4th North Ring, Haidian District, Beijing, China ' Sinopec Petroleum Exploration and Production Research Institute, Olympic Building, No. 267, 4th North Ring, Haidian District, Beijing, China ' Sinopec Petroleum Exploration and Production Research Institute, Olympic Building, No. 267, 4th North Ring, Haidian District, Beijing, China ' Sinopec Petroleum Exploration and Production Research Institute, Olympic Building, No. 267, 4th North Ring, Haidian District, Beijing, China ' Sinopec Petroleum Exploration and Production Research Institute, Olympic Building, No. 267, 4th North Ring, Haidian District, Beijing, China ' Aerospace Engineering School, Mengminwei Science and Technology Building, Tsinghua University, Haidian District, Beijing, China

Abstract: Compared with the conventional reservoir, the production rate in shale gas reservoir declines rather quickly during the early production period and conventional decline rate analysis becomes not suitable for shale gas production. In this article, we build a four parameter empirical decline model considering the varying decline exponent and terminal decline rate and propose a simple but efficient calculation method. By analyzing the sharp-to-shallow decline trend, a sophisticated decline rate form was assumed, which takes the initial decline rate, terminal decline rate and the curvature of the decline rate curve into consideration. For shale gas reservoirs with short production time and little production data, the early production data may not reflect the real terminal decline rate. A modification for such cases is also proposed. Field examples from a synthetic shale gas reservoir, Barnett shale gas, Haynesville shale gas and Fuling shale gas were used to test our newly proposed model. [Received: October 27, 2017; Accepted: January 30, 2018]

Keywords: shale gas; reserve estimation; varying decline exponent; terminal decline rate.

DOI: 10.1504/IJOGCT.2019.103088

International Journal of Oil, Gas and Coal Technology, 2019 Vol.22 No.3, pp.291 - 314

Received: 27 Oct 2017
Accepted: 18 Mar 2018

Published online: 15 Oct 2019 *

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