Field experience and numerical investigations of minifrac tests with flowback in low-permeability formations  

作　　者：Yu Fan Rui Yong Bo Zeng Yi Song Xiaojin Zhou Bin Xu 

机构地区：[1]Shale Gas Research Institute of PetroChina Southwest Oil and Gas Field Company,Chengdu 610051,China [2]Origin Geomechanics Inc.,Calgary T3H 0X6,Canada [3]Concordia University,Montreal,Quebec H3G 1M8,Canada

出　　处：《Underground Space》2021年第3期300-315,共16页地下空间（英文）

摘　　要：In this study,flowback-assisted minifrac tests were conducted in low-permeability shale and salt formations to measure the in situ stress.An injection/flowback testing protocol was implemented in each test to achieve accuracy and efficiency.Accurate and efficient injection/flowback testing is very important,given the impermeable nature of these formations and the need to complete each test as quickly as possible.Each flowback cycle yields a distinct and repeatable fracture closure signature,simplifying the interpretation of the fracture closure pressure.The objective of this paper is to share our field experience and to present a numerical analysis of the flowback test pressure responses,fracture closure behaviors,and fracture closure diagnostic methods.Examples from open-hole and casedhole minifrac tests are used to demonstrate site operation procedures.Then,two numerical models are presented for simulating the fracture closure behavior during a flowback test.Field evidence is provided to demonstrate that the fracture closure pressures from the flowback tests are identical to those from tests without flowback.The fracture closure diagnostic methods for flowback tests are discussed,and it is found that the G-function diagnostic method yields a distinct fracture closure signal during the flowback tests.This study is intended to provide additional insights regarding flowback tests by sharing our successes,experience,and knowledge,thereby benefiting the industry.

关 键 词：In situ stress determination Minifrac FLOWBACK Fracture closure diagnostic method Numerical simulations 

分 类 号：TU43[建筑科学—岩土工程]