He Pei, Pan Linhua, Lu Zhaohui, Zhou Jiankun, Meng Chun, Yu Huawen
National and Local Joint Engineering Research Center of Shale Gas Exploration and Development, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China.
Key Laboratory of Shale Gas Exploration, Ministry of Natural Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China.
ACS Omega. 2022 Jul 26;7(31):27490-27502. doi: 10.1021/acsomega.2c02517. eCollection 2022 Aug 9.
Hydraulic fracturing plays an important role in the commercial development of unconventional oil and gas, which is directly related to the production of oil and gas wells. An accurate evaluation is critical for hydraulic fracturing, but it is urgent to propose a quantitative assessment of hydraulic fracturing fracture propagation for realizing hydraulic fracturing fracture propagation and multiposition permeability measurement under an in situ stress environment. Herein, a true triaxial stress loading and permeability testing device was designed and fabricated, and a permeability evaluation model was established under various states, which can realize the accurate measurement of multiple faces and the total permeability of tight specimens before and after hydraulic fracturing. It can directly measure permeability under the conditions of the true triaxial fracture propagation experiment. The comparative experimental result shows that the new technique can quantitatively evaluate the fracture propagation experiment of true triaxial hydraulic fracturing. The overall permeability and the directional permeability of the five faces were obtained, and the fracture propagation was evaluated by comparing the change in permeability. The test permeability error rate is within ±10%. Furthermore, a more refined evaluation of hydraulic fracturing fracture propagation can be carried out based on the fracture observation and AE event results. The research results provide a new strategy for a more quantitative and refined evaluation of fracture propagation and help to optimize the parameters of hydraulic fracturing.
水力压裂在非常规油气的商业开发中起着重要作用，直接关系到油气井的产量。准确评估对于水力压裂至关重要，但为了在原地应力环境下实现水力压裂裂缝扩展和多位置渗透率测量，迫切需要提出一种对水力压裂裂缝扩展的定量评估方法。在此，设计并制造了一种真三轴应力加载与渗透率测试装置，建立了不同状态下的渗透率评估模型，该模型能够实现对致密试样在水力压裂前后多面及总渗透率的精确测量。它可以在真三轴裂缝扩展实验条件下直接测量渗透率。对比实验结果表明，该新技术能够对真三轴水力压裂的裂缝扩展实验进行定量评估。获得了五个面的整体渗透率和定向渗透率，并通过比较渗透率变化来评估裂缝扩展。测试渗透率误差率在±10%以内。此外，基于裂缝观测和AE事件结果，可以对水力压裂裂缝扩展进行更精细的评估。研究结果为更定量、更精细地评估裂缝扩展提供了新策略，有助于优化水力压裂参数。
