摘要
破裂压力可以有效地反映压裂过程中岩石的破裂难易程度,是压裂施工设计的关键参数.目前破裂压力预测主要通过现场或室内测试的方法,具有费用高、耗时长的特点,且在非均质性较强的地层开展测试得到的结果不具备代表性.本文基于损伤力学理论,利用COMSOL和MATLAB软件对流固温三场耦合作用下的致密砂岩破裂机制开展研究,形成了破裂压力预测方法,并对致密砂岩破裂压力敏感性因素进行了分析.数值模拟结果表明:本文所建立的模拟方法得到的破裂压力预测值与实验测试得到的破裂压力值相比误差较小,满足工程需求.流固温三场耦合作用下,储层非均质性越强,岩石破碎程度越大,破裂压力越低;储层非均质性越极端(非均质性越强或不存在非均质性),弹性模量变化对破裂压力的影响越敏感.温度差对破裂压力影响明显,温度差为200℃情况下得到的破裂压力仅为52 MPa,为不考虑温度差情况下破裂压力的39%;弹性模量降低30 GPa,破裂压力下降幅度达78%.本文方法具有成本低、精度较高的特点,具有较强实用性和推广价值.
The fracture pressure can effectively reflect the likelihood of rock fracturing during the fracturing process and is a key parameter in the design of fracturing operations.Currently,the prediction of fracture pressure mainly relies on field or laboratory testing methods,which are characterized by high costs and long durations.Moreover,the results obtained from testing in highly heterogeneous strata lack representativeness.Based on the theory of damage mechanics,in this paper we utilize the COMSOL and MATLAB software to investigate the fracturing mechanism of tight sandstone under the coupled action of fluid-solid-temperature fields,establish a method for predicting fracture pressure,and analyze the sensitivity factors of fracture pressure in tight sandstone.The numerical simulation results indicate that the prediction values of fracture pressure obtained using the simulation method established in this paper have small errors compared to those obtained through experimental testing,satisfying engineering requirements.Under the coupled action of fluid-solid-temperature fields,the stronger the heterogeneity of the reservoir,the greater the degree of rock fragmentation and the lower the fracture pressure.When the heterogeneity of the reservoir is more extreme(either very strong or nonexistent),the fracture pressure is more sensitive to the elastic modulus.Temperature difference has a significant impact on the fracture pressure.For example,when the temperature difference is 200℃,the obtained fracture pressure is only 52 MPa,which is 39%of the fracture pressure obtained without considering the temperature difference.When the elastic modulus decreases by 30 GPa,the fracture pressure decreases by up to 78%.The method proposed in this paper is characterized by the low cost and the high accuracy,demonstrating high practicality and application value.
作者
任广磊
孙华超
杨京华
张凌筱
REN Guanglei;SUN Huachao;YANG Jinghua;ZHANG Lingxiao(Exploration and Development Research Institute of Sinopec North China Oil and Gas Branch,Zhengzhou 450006,Henan,China;School of Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China)
出处
《力学季刊》
CAS
CSCD
北大核心
2024年第4期1097-1106,共10页
Chinese Quarterly of Mechanics
基金
中国石化开发项目群(P23031)。
关键词
致密砂岩
破裂压力
数值模拟
流固温三场耦合
tight sandstone
fracturing pressure
numerical simulation
three coupling fluid-solid-temperature fields
