库车坳陷克深气田超深层致密储层产能控制因素

塔里木盆地库车坳陷克深气田是世界罕见的超深超高压高温裂缝性致密砂岩气藏,基质低孔特低渗,裂缝是最主要的渗流通道,气藏产能平面分布差异大、高效开发井布署难等问题是制约气田高效开发的关键。在气藏地质特征、断裂裂缝系统、基质物性、储层微观结构和气水关系分布等研究的基础上,结合储层地应力研究,从多个角度系统解剖了主力产气区克深2区块高效井和低效井的差别,揭示了产能的主控地质因素和钻完井因素,提出了高效井布署、实施及开发合理技术政策。研究结果表明:井筒及井周裂缝发育程度、产状、有效性、储层力学特征、气柱高度及其相互之间的匹配关系是制约气井产能的先天地质因素;井周断层、裂缝、隔夹层、气水分布、投产井段及由此制定的合理开发技术政策是制约长期高产、稳产的核心因素;完钻井深、完井投产井段、射孔段优化和储层改造工艺是否合理,也是气井高产、稳产的关键;同时,基质储层物性及孔喉特征对产能也有一定影响。综合分析认为,在高部位集中布井是实现该类气藏高效开发最直接、最有效的手段。

Controlling factors for productivity of ultra-deep tight reservoirs in Keshen gas field,Kuqa depression

Keshen gas field in the Kuqa depression of Tarim Basin is a rare, ultra-deep, ultra-high pressure, and high-temperature fractured tight sandstone gas reservoir in the world. Low porosity and super-low permeability of matrix, fracture as the dominant seepage channel, large differences in the planar distribution of gas reservoir productivity, and difficulties in deployment of efficient development wells are key problems restricting the efficient development of gas field. Based on studying the geological characteristics of gas reservoir, the fracture system, the physical properties of matrix, reservoir microstructure, and the distribution of gas-water relationship, in combination with researches on the ground stress of reservoir, this paper systematically analyzes the difference between high-production and low-production wells in the main gas production area-Keshen 2 block from multiple perspectives, reveals the main geological factors controlling productivity and the factors influencing well drilling and completion, and proposes reasonable technical policies for the deployment, implementation, and development of efficient wells. The research results show that the development degree, occurrence, and effectiveness of fractures in the well bore and its periphery, mechanical characteristics of the reservoir, height of gas column and their matching relationships are congenital geological factors that restrict the productivity of gas well; faults in the periphery of well bore, fractures, interbeds, gas and water distribution, brought in well section, and reasonable technology policies made accordingly for optimization of perforated intervals and reservoir reform are the key factors that restrict the long-term high and stable well yield. Moreover, the physical properties and pore throat characteristics of matrix reservoirs also have a certain impact on productivity. Through a comprehensive analysis, it is believed that well spacing concentrated at high locations is the most direct and effective way to achieve the efficient development of this type of gas reservoir.