不同含油、含水饱和度致密砂岩真三轴力学特征  

True triaxial mechanical characteristics of tight sandstone with different oil and water staturation

作　　者：许鹏祥 陈向东 刘钊 程鑫[1,2] 屈怡倩 李秋实[4] 马春晓 吴汉宁[1,2] Xu Pengxiang;Chen Xiangdong;Liu Zhao;Cheng Xin;Qu Yiqian;Li Qiushi;Ma Chunxiao;Wu Hanning(State Key Laboratory of Continental Dynamics,Xi'an 710069,China;Department of Geology,Northwest University,Xi'an 710069,China;No.5 Oil Production Plant of Changqing Oilfield Company,PetroChina,Xi'an 710200,China;No.8 Oil Production Plant of Changqing Oilfield Company,PetroChina,Xi'an 710021,China;Research Institute of Yanchang Petroleum Group Research Institute,Xi'an 710065,China)

机构地区：[1]西北大学大陆动力学国家重点实验室,西安710069 [2]西北大学地质系,西安710069 [3]中国石油长庆油田分公司第五采油厂,西安710200 [4]中国石油长庆油田分公司第八采油厂,西安710021 [5]延长石油集团研究院,西安710065

出　　处：《地质科技通报》2023年第1期70-77,共8页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目(41304049)。

摘　　要：致密砂岩储层中水、石油或天然气等流体赋存可能会对致密砂岩的力学特征产生影响。选取鄂尔多斯盆地蟠龙地区延长组致密砂岩,利用YSZS-2000型多功能电液伺服岩石真三轴试验机对不同含油和含水饱和度致密砂岩力学特征进行了研究。结果表明:(1)含油性对砂岩的峰值应力和弹性模量产生弱化作用,表现为峰值应力和弹性模量随着含油饱和度的增大而减小,“准饱和”时峰值应力可下降5.35%,弹性模量可下降11.38%;(2)含水砂岩根据其吸水特性曲线分为Pa型与Pb型,含水性对砂岩的峰值应力产生弱化作用,饱和时Pa型砂岩峰值应力可下降11.58%,Pb型砂岩峰值应力可下降15.95%;(3)观察实验后浸油砂岩内部结构发现,油集中分布于砂岩矿物间裂隙,对破裂面产生润滑作用从而降低了砂岩的承载力。本研究成果可以对致密油气的开发提供可靠依据。The occurrence of fluids such as water, oil or natural gas in tight sandstone reservoirs may affect the mechanical characteristics of tight sandstone. This paper selects tight sandstones of Yanchang Formation in Panlong area of Ordos Basin, and uses YSZS-2000 multifunctional electro-hydraulic servo rock true triaxial testing machine to study the mechanical characteristics of tight sandstones with different oil and water saturation degrees. Results show that:(1)The oil contents have a weakening effect on the peak stress and elastic modulus of sandstones. Both the peak stress and elastic modulus decrease with the increase of oil saturation. The peak stress can be reduced by 5.35% and the elastic modulus can be reduced by 11.38% when it is "quasi-saturated".(2)Sandstones containing water can be divided into the Pa-type and the Pb-type according to the water absorption characteristic curve. Water content weakens the peak stress of sandstones. When saturated, the peak stresses of a Pa-type and a Pb-type sandstone can be reduced by 11.58% and 15.95%, respectively.(3)After observing the internal structure of the oil-soaked sandstone, it is found that the oil is concentrated in the fractures between the sandstone minerals, which lubricates the fractured surface and reduces the bearing capacity of the sandstone. The research outcomes of this article can provide a reliable basis for the exploitation of tight oil and gas.

关 键 词：真三轴实验 致密砂岩 力学特征 峰值应力 弹性模量 

分 类 号：TU452[建筑科学—岩土工程]