致密性气藏储层损害实验方法探讨与评价

Investigation on Experimental Methods and Evaluation of Tight Gas Reservoir Damage

致密性气藏具有低孔低渗、高含水饱和度、高应力敏感性和黏土矿物发育等特点,气体渗透率一般小于0.001 mD,这使得气藏损害具有不同于油藏损害的特殊性。目前国内外尚未形成统一的针对致密性气藏储层损害评价方法,而常规储层敏感性评价方法采用液相为驱替介质,在评价致密储层时出现测试时间长、实验误差大、易发生应力敏感的局限。因此,通过对致密性气藏储层损害方法研究,制定了一套“致密性气藏储层损害评价方法,评价了BZ19-25区块储层岩心敏感性损害,并采用行业标准方法对其敏感性损害进行复测,结果表明新方法测试结果与行业标准方法测试结果一致,说明新研究的方法具有可靠性,适合致密性气藏储层损害评价。

A tight gas reservoir generally has low porosity,low permeability,high water saturation,high stress sensitivity and high clay content,the gas permeability of the tight gas reservoir is generally less than 0.001 mD.Gas reservoir damage is thus different from oil reservoir damage because of these characteristics.Presently there is no commonly agreed method for evaluating tight(included fractured)gas reservoir damage worldwide.In the common reservoir sensitivity evaluation method a liquid is used as displacing medium.This method is time consuming and is subject to great experimental errors and stress sensitivity.To overcome these shortages,a new evaluation method was developed based on the study of tight(including fractured)gas reservoir damage,and a set of procedure developed to evaluate the damage to tight(porous and fractured)gas reservoirs.Using this new method,reservoir cores from the block BZ19-25 was evaluated,giving results that were consistent to those obtained with standard industrial methods.This proves that the new method is reliable and is suitable for evaluating damage to porous and fractured gas reservoirs.