【摘要】 在水压致裂应力测量压裂特征参数中,瞬时关闭压力ps是重要的研究内容,因为它不仅直接代表最小水平主应力,而且在计算最大水平主应力时,该值又是重要的参数。ps判读的准确性和可靠性直接关系到水压致裂应力测量结果的可靠性与精度。结合3个典型的水压致裂测试曲线,分析了单切线法、dp/dt方法、马斯卡特方法和dT/dP法4种常用判读关闭压力方法的取值特点和适用性。结果表明,该4种判读方法对于不同形态的水压致裂测试曲线不具有普遍适用性,因此,对不同形态的水压致裂测试曲线进行判读关闭压力时,所选取的判读方法也不同。对于岩石完整、原生裂隙及节理不发育、岩石结构致密的水压致裂压裂段,应选取以上4种方法中2种或2种以上方法进行判读瞬时关闭压力值;对于岩石完整性差、原生裂隙及节理较发育、岩石结构较破碎的水压致裂压裂段,为取得比较可靠有效的关闭压力值,建议用单切线法计算机自动取值和dp/dt方法所取的关闭压力值。更多还原

【Abstract】 The instantaneous shut-in pressure(ps) is an important parameter in the hydraulic fracturing characteristic parameters.Not only is it assumed to be equal the minor horizontal stress,but also is an important factor to calculate the maximum horizontal stress.The accuracy and reliability of the determination of ps are directly related to that of the hydraulic fracturing results.The applicability and value features of four methods(the single tangent,dp/dt,lg(p)-t and dT/dP methods) frequently used to determine ps are analyzed combined with three examples of test records.The results reveal that the four methods are lack of general applicability at different forms of pressure records.Therefore,different methods chosen to determine the instantaneous shut-in pressure are various for different pressure records of hydraulic fracturing stress test.Aiming at the hydraulic fracturing segments with intact rock,undeveloped preexisting fissures or joints and compact structure,two or more than two kinds of four methods should be applied to determine the shut-in pressure.The methods of technique of single tangent and dp/dt should be suggested to obtain more reliable value of shut-in pressure directing at hydraulic fracturing segments with incomplete rock,more developed preexisting fissures or joints and incompact structure.更多还原