致密储层脆性测井解释方法研究

Log Interpretation Methods for Measuring the Brittleness of Tight Reservoir

随着水平井和体积压裂改造技术的突破,致密油气已经成为现实接替领域。脆性是致密储层测井评价的主要内容,选择合适的方法进行脆性计算及其脆性变化规律的描述需深入研究。通过对计算脆性指数的矿物组分法和弹性参数法的分析和评价,指出这2种方法解释脆性的关键技术,为脆性解释方法选择提供依据;假设地层为块状均质条件下,采用理论推导,得到脆性指数与横纵波时差比值的关系图,以此确定脆性随岩石分选性、泥质含量、物性等变化的规律;根据储层横纵波时差比值变化范围,确定脆性指数解释的合理范围。针对徐家围子断陷沙河子组致密储层,选择弹性参数法解释脆性,为该区致密气储层勘探开发提供了可靠保障。

Tight oil and gas have become a successor after the breakthrough on horizontal well and volume fracturing technology.Rock brittleness is a key factor for evaluating tight reservoirs in log interpretation.Which suitable methods should be selected is important for calculating brittleness and describing brittleness changes of rocks.The effectiveness of mineral component method and elastic parameter method for calculating rock brittleness index are analyzed,based on which brittleness interpretation method can be selected.Assuming that underground formation is massive and homogeneous,the relationship between brittleness index and v s/v p ratio can be established by theoretical deduction,then how rock brittleness changes with rock sortability,shale content,physical properties can be determined.Finally,the reasonable range of brittleness index interpretation is determined according to the v s/v p ratio.Application of the elastic parameter method for interpreting the tight reservoir of the Shahezi formation in the Xujiaweizi fault depression provides a reliable basis for the exploration and development of tight gas reservoirs in this area.