胶凝酸对顺北区块奥陶系碳酸盐岩力学特性的影响

从宏观和微观角度研究了压裂现场所用胶凝酸对塔河油田顺北区块奥陶系碳酸盐岩力学特性的影响，从而为目标区块的碳酸盐岩储集层油藏的高效开发提供依据。通过开展胶凝酸处理碳酸盐岩岩样后的微观组构及其力学特性的影响试验结果可知：顺北区块奥陶系碳酸盐岩具高碳酸盐矿物、低石英、少杂质的矿物组分特征；静态酸岩反应后微观矿物晶间距明显增大，矿物中方解石含量由93%减至88%，仍属于高脆性可压裂储集层；不同酸液的静态酸岩反应及其单轴压缩试验可知最佳反应时间为30 min，各物理参数和力学指标劣化效应显著；胶凝酸处理30 min后岩样的密度和纵波速度明显减小，其抗拉抗剪强度明显弱化；胶凝酸作为反应酸液，对碳酸盐岩岩样产生宏观结构的酸蚀和微观孔隙裂隙的损伤，其物理参数和力学指标等均产生了劣化效应，故胶凝酸对碳酸盐岩储集层压裂改造和裂缝扩展具有重要意义。

Influences of Gelled Acid on Mechanical Properties of the Ordovician Carbonate Rocks in Block Shunbei,Tahe Oilfield

From the perspective of macroscopic and microscopic points, the paper studies the influences of gelled acid used during fracturing on the mechanical properties of the Ordovician carbonate rocks in the Block Shunbei of Tahe oilfield, which could provide basis for efficient development of the carbonate reservoirs in the target blocks. The experiments were carried out to test the influences on microscopic structures and its mechanical properties of carbonate rock samples after treatment by gelled acid and the results showed that the mineral components of the Ordovician carbonate rocks in Shunbei area are characterized by high contents of carbonate minerals, low content of quartz and a few impurities; after the static acid-rock reaction, the intercrystal distance of minerals significantly increases and the calcite content reduces from 93% to 88%, indicating a high-brittleness fracturable reservoir; the static acid-rock reactions in different acid fluids and the corresponding uniaxial compression tests show that the optimal reaction time is 30 minutes, and each physical parameter and mechanics index get worse obviously; the density and P-wave velocity decrease obviously after 30 minutes of gelled acid treatment for the rock samples and the tensile and shear strengths significantly drop; the gelled acid as a reaction acid fluid can result in acid etching to the macrostructures and some damages to micropores of the carbonate rock samples. Therefore, the gelled acid is of great significance for carbonate reservoir fracturing and fracture propagation