快速评价页岩含气量的新方法

A New Method for Rapid Evaluation of Shale Gas Content

梁洪彬 张烈辉 陈满 赵玉龙 向祖平

LIANGHongbin ZHANGLiehui CHENMan ZHAOYulong XIANGZuping

油气藏地质及开发工程国家重点实验室·西南石油大学, 四川 成都 610500 四川长宁天然气开发有限责任公司, 四川 成都 610500 重庆科技学院石油与天然气工程学院, 重庆 沙坪坝 401331

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Sichuan Changning Natural Gas Development Co. Ltd., Chengdu, Sichuan 610500, China School of Petroleum Engineering, Chongqing University of Science & Technology, Shapingba, Chongqing 401331, China

在页岩气藏开发中，明确页岩含气量变化规律是气藏开发方案合理制定的关键，但由于吸附气解吸后会与游离气共同流动，难以获取二者变化特征，常用的测井解释法与现场解吸法因受环境、设备以及人为因素的影响使得两种方法解释结果存在较大误差，为页岩气藏开发研究带来困扰。因此，利用粉体工程中Horsfield填充理论建立了基于容积法的页岩气等温吸附实验的物理模型，提出了确定吸附气与游离气比例关系的方法，结合实测数据验证了方法的可行性。该方法较之于测井解释法、现场解吸法更简单、更精确，且易于计算，能定量地表征页岩气藏开发过程中吸附气量与游离气量的变化特征。结果表明，页岩气藏开发时压力下降显著，孔道内的主要气源从游离气向吸附气转变时对应的压力点与孔隙度呈负线性相关。

It is important to make clear the variation rule of shale gas content for make reasonable development plan of gas reservoir. However, it is difficult to obtain the characteristics of shale gas content as adsorbed gas flow with free gas after desorption during the development. Due to the influence of environment, equipment and human factors, the interpretation results based on the two common methods of logging interpretation and field desorption have great errors, which brings trouble to research on the development theory of shale gas reservoirs. Therefore, the physical model for shale gas isothermal adsorption experiment based on volume method is established by using Horsfield filling theory, and the method to determine the proportion of adsorbed gas and free gas is proposed. This method is verified to be feasible based on the measured data. Compared with well logging interpretation method and field desorption method, this method is more concise and accurate, and easier to calculate. Furthermore, the variation characteristics of adsorption gas and free gas can be quantitatively described by this method during the reservoirs development. The results show that when the reservoir pressure decreases significantly and the main gas source in the pore changes from free gas to adsorbed gas, the corresponding pressure of transition point is negatively linearly correlated with the porosity.

10.11885/j.issn.1674-5086.2019.03.29.02