Title: Practical shale gas decline analysis in Changning shale gas play - a variable pressure drop study

Authors: Man Chen; Hongzhi Yang; Xiaotao Zhang; Xin Jiang; Majia Zheng; Zhou Zhang

Addresses: Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China ' Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China ' Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China ' Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China ' Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China ' Room 531, RIPED Building, 83th, Section 1 North Jianshe Road, Chenghua District, Chengdu City, Sichuan Province, China

Abstract: The Upper Ordovician Wufeng - Lower Silurian Longmaxi Shale in Changning, Southern Sichuan Basin, China has recently been developed by utilising a combination of horizontal drilling and multi-stage hydraulic fracturing. Forecasting production and estimating ultimate recovery (EUR) for these wells is vital to continually optimise development scheme. Regrettably, all of the shale gas decline curves in literature are using time-rate data under constant bottomhole pressure assumption, which greatly violate field observations, as many wells is produced under variable pressure variable rate conditions. This work presents a new approach - variable pressure YM stretched exponential production decline method (VP-YM-SEPD) to handle the complex production data of field wells in Changning. Two field examples are presented to validate the new method. The outcome of this new approach should greatly help reservoir engineers to forecast field shale gas production in variable rate/variable pressure drop cases with a limited history. [Received: April 21, 2017; Accepted: December 1, 2017].

Keywords: shale gas decline; variable pressure YM-SEPD; production forecast; Changning; Southern Sichuan Basin.

DOI: 10.1504/IJOGCT.2018.093136

International Journal of Oil, Gas and Coal Technology, 2018 Vol.18 No.3/4, pp.353 - 383

Received: 24 May 2017
Accepted: 01 Dec 2017
Published online: 10 Jul 2018 *

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