低效气藏成因层次剖析

由于我国低效气藏的储量所占比例很大，故而有必要对其进行深入研究，形成适合于不同层面的研究方法和思路，以期达到指导勘探开发生产的目的。为此，将低效气藏剖析为四个层面（气藏开发特征层面、现有地质特征层面、历史地质成因层面、预测及改造层面），并用层次分析法对其进行了研究：第一层次是直接由生产来认识，第二层次通过分析、化验、监测来了解，第三层次通过地质过程和地质历史回溯来表述，第四层次依据现有地质理论，通过地质过程叠合，最终达到预测、改造、有效动用低效气藏的目的。研究结果认为，可以依据不同层次特征对低效气藏进行分类评价：第一层次从经济效益出发，依据投入产出比进行分类；第二层次着眼气藏现今地质特征，表征其地质特征，而储层分布、渗透性则为分类的主要依据；第三层次从气藏形成地质过程着手，分析低效气藏形成过程，沉积和成岩作用作为分类的关键因素；第四层次基于气藏地质特征，预测开发动态，改造气藏特征，促使气藏有效动用。

ANALYTICAL HIERARCHY PROCESS OF LOW-EFFICIENCY GAS RESERVOIRS

Low-efficiency gas reservoirs account for a considerable proportion of the total gas reserves in China, thus it is necessary to develop methodologies and ideas suitable for different study hierarchies based on an in-depth study for guiding exploration and development of this kind of gas reservoirs. Low-efficiency gas reservoirs are organized into 4 hierarchies, including gas reservoir development features, current geological features, historical geologic origin, as well as reservoir prediction and modification, and are studied through analytical hierarchy process. On the first hierarchy, the gas reservoirs are studied directly with production data. On the second hierarchy, the gas reservoirs are understood through analysis, testing and monitoring. On the third hierarchy, they are described through reconstruction of geologic process and history. While on the fourth hierarchy, prediction, modification and effective production of low-efficiency gas reservoirs are finally realized through superim-position of geologic processes on the basis of the current geologic theories. It is believed that the low-efficiency gas reservoirs can be classified and evaluated according to their features on different hierarchies. On the first hierarchy, reservoirs are classified according to the input/output ratio. On the second hierarchy, attentions are focused on the current geologic features, and reservoir distribution and permeability are taken as the main criteria for reservoir classification. On the third hierarchy, the process of reservoiring is studied through first analyzing the geologic process of gas reservoir formation, and sedimentation and diagenesis are taken as the key criteria of reservoir classification. While on the fourth hierarchy, reservoir behaviors are predicted and reservoir features are modified based on the geologic features, so as to effectively bring the gas reservoirs into production.