基于矿物组分与断裂韧度的页岩地层脆性指数评价模型

Evaluation Model for Shale Brittleness Index Based on Mineral Content and Fracture Toughness

廖东良 肖立志 张元春

Liao Dongliang Xiao Lizhi Zhang Yuanchun

油气资源与探测国家重点实验室(中国石油大学(北京)), 北京 102249; 中国石化石油工程技术研究院, 北京 100101

State Key Laboratory of Petroleum Resources and Prospecting(China University of Petroleum(Beijing), Beijing, 102249, China; Sinopec Research Institute of Petroleum Engineering, Beijing, 100101, China

利用岩石力学参数计算页岩地层脆性指数其结果存在不确定性，而由矿物组成得到的结果不能反映地层的实际脆性。为此，在用矿物组分计算地层脆性的基础上，引入断裂韧度作为每种矿物的加权系数，建立了页岩地层脆性指数评价新模型。用页岩地层的岩石力学模型、脆性矿物模型和建立的新模型分别计算了某井页岩地层的脆性指数，并对其结果进行了对比。结果发现，在岩石力学参数异常段，新模型的评价结果比岩石力学模型高10%左右，且评价结果与压裂效果一致。研究表明，新模型的脆性指数与断裂韧度之间呈负线性关系，地层断裂韧度越大，则脆性指数越小，反之亦然。分析认为，该模型有效避免了单一矿物含量模型带来的缺陷，同时新模型与页岩地层的含气量和有机质含量无关，对页岩地层来说是一种高效的模型。

Some uncertainties exist in shale brittleness index evaluation by using rock mechanics parameters.While it cannot present actual formation brittleness by using mineral content.A new evaluation model for shale brittleness was established based on conventional calculation method using mineral content and integrating fracture toughness as weighing coefficient for each mineral.In this paper,the new model,rock mechanical model and mineral content model were compared.It was found that,for an interval with abnormal rock mechanics properties,the new model provided a result aproximately 10% higher than the rock mechanical model and consistent with the stimulation results.Moreover,a negative linear relationship existes between fracture toughness and brittleness index-higher fracture toughness,lower brittleness index,and vice versa.Analysis showed that the new model avoided the defects of single mineral content model and was irrelevant to gas and organic materials in shale formation.Therefore,the new model is efficient for shale formation evaluation.

中国石油化工股份有限公司油田事业部项目“测井资料在压裂工程设计中的应用”（编号：PT1305）部分研究内容。

https://doi.org/10.3969/j.issn.1001-0890.2014.04.007