低压致密气藏气井产能潜力的识别技术研究

四川盆地川南、川中过渡带荷包场-界石场地区的须家河组砂岩储层是一套典型的低压致密储集层。由于储层具有低压、低渗、高束缚水饱和度的特点，其渗流机理不同于常规储层。气井在低渗、低压力系数的储层开发过程中表现为低自然产能，有些井受到钻井污染，基本没有产量。通常水力加砂压裂是经济高效开发此类气藏的必要手段，但由于常规低渗透储层试井方法及油气测试手段对低产甚至无产量气井的测试、评价受到限制，使得压裂前储层物性和气井产能无法确定，无法对气井压裂效果做出客观正确地评价。为此，基于脉冲试井不稳定渗流原理，开展了低压致密气藏气井微型注入测试技术研究，提出了确定低压致密气藏储层物性和气井产能识别的新方法。应用该方法可以准确评估低渗致密气藏储层渗流物性，确定气井生产潜力，并为低丰度、低压渗致密气藏储层效益开发提供了理论依据。

THE RESEARCH ON THE WELL PRODUCTIVITY IDENTIFICATION IN LOW PRESSURE AND TIGHT GAS RESERVOIR

Xujiahe sandstone formation is a set of typical low pressure and tight gas reservoir in the Hebaochang-Jishichang Area between central and southern Sichuan Basin. Due to the characteristics of low pressure, low permeability, and high irreducible water saturation, the penetration mechanism of Xujiahe reservoir differs from other conventional reservoir. Gas wells of low permeability and low pressure formation demonstrate low productivity and some are almost yield-less owing to drilling contamination. Generally, hydraulic and sand fracturing is necessary to develop this type of gas reservoir economically and efficiently. Yet, because well test method and measures effective for conventional low permeability reservoir are inefficacious for testing and evaluation of low or even no yield gas wells, pre-fracturing reservoir physical property and well productivity are unable to be evaluated, therefore it is impossible to carry out appropriate appraisal of well fracturing effects. Based on unsteady flow pulse testing method, this paper studies micro-injection testing technology of low pressure tight gas reservoir and introduces a new method of formation evaluation and well productivity identification, which provides an efficient way to evaluate formation performance, identify gas well potential and provide theoretical basis for economic development of low abundance, low pressure, tight gas reservoirs.