裂缝－孔洞型碳酸盐岩储层应力敏感性实验研究

油气储集层具有应力敏感性，以往研究多关注于孔隙型储层和裂缝型储层的应力敏感性，而缝洞型储层的应力敏感性研究鲜见报道。以塔河油田裂缝-孔洞型碳酸盐岩储层为对象，选取天然缝岩样、人工缝岩样、单孔洞岩样和双孔洞岩样，开展应力敏感性实验研究。研究区选取的4组12块岩样的实验结果表明，天然缝岩样、人工缝岩样、单孔洞岩样及双孔洞岩样应力敏感系数分别为0.64、0.75、0.58和0.61，应力敏感程度分别为中偏强、强、中偏强及中偏强。岩样卸载60h后，渗透率最终恢复率分别为69.84%、4.36%、11.86%和38.75%。研究表明，孔洞的存在弱化了裂缝岩样应力敏感程度。孔洞的发育又增加了钻井完井液漏失损害的控制难度。

Simulated Experiment on Stress Sensitivity in Fractured-Vuggy Reservoir

Stress sensitivity exists in oil-gas reservoir. There is a lot of report about stress sensitivity in porous and fractured reservoirs while less attention is paid to stress sensitivity in the fractured-vuggy reservoir. The fractured-Vuggy carbonate reservoir of Tahe oilfield as a case was subjected to simulate stress sensitivity experiment by choosing natural fractured, artificial fractured, single-cavity and double-cavity core samples. Experimental results from 12 rock samples of 4 groups show that stress-sensitive coefficients of the natural fractured, artificial fractured, single cavity, and double cavity core are 0.64, 0.75, 0.58 and 0.61 respectively, corresponding to the stress-sensitive degree changed from med|strong,strong,med-strong, and med-strong, respectively. After 60h of samples download, the final return permeability rate of rock samples is 69.84%, 4.36%, 11.86% and 38.75%, respectively. Thus, the existence of cavity would weak the stress|sensitive degree of fractured reservoir, and the development of cavity also increases the hardness of controlling drill-in fluid loss damage.