裂缝-孔隙型低渗气藏损害室内评价方法研究

低渗透裂缝-孔隙型天然气藏具有低孔隙度、低渗透率、高含水饱和度、高应力敏感性和高毛细管压力的特点，使得气藏损害具有不同于油藏损害的特殊性。建立与裂缝-孔隙型气藏相适应的评价方法和标准，搞清裂缝-孔隙型气藏的损害机理，是进行裂缝-孔隙型气藏保护的关键。而建立裂缝-孔隙型气藏评价方法的核心是裂缝性岩心的制备技术。文中提出了3种裂缝性岩样的制备方法，即天然裂缝性岩样的骑缝钻取法、天然岩心人造裂缝方法和预制裂缝压制法。评价实验表明，低渗透裂缝-孔隙性致密砂岩气藏具有很强的应力敏感性和水锁效应，水锁损害和应力敏感性损害是其主要损害因素，说明裂缝性岩样制备方法、应力敏感性和水锁效应评价方法可行。

Evaluation Method for Formation Damage in Low Permeable Fractured-Porous Gas Reservoir

Due to the characteristics of low porosity, low permeability, high water saturation, high pressure sensitivity and high capillary pressure, low permeable fractured-porous gas reservoir has many differences in formation damage with normal oil reservoir. The simulation test of gas flowing in fractured-porous reservoir is difficult because of the gas compressibility and gas-liquid multiple-phase flowing. It is the key to the formation damage control to form an evaluation method for formation damage and understand its damage mechanism of fractured-porous gas reservoir. The preparation techniques of fractured core are the important aspects in the evaluation method. Three preparation techniques of fractured core are put forward in this paper. The three techniques are direct drilling on natural fractured core, producing fracture on natural matrix rock with certain apparatus and prefabricating fracture with special materials. The results show that they have strong pressure sensitivity and water blocking effect which are the main damage factors in low permeable fractured-porous sandstone gas reservoir. All these also indicate that the methods for fractured core manufacturing, evaluation of pressure sensitivity and water blocking effect are practicable and can be applied in lab testing.