苏里格气田压裂气井合理关井测压时间

DETERMINATION OF REASONABLE SHUT-IN PERIOD FOR PRESSURE MEASUREMENT IN FRACTURED GAS WELLS OF SULIGE GAS FIELD

为了解决压裂气井压力恢复曲线不能出现边界反映段,以及渗流不能反映地层中真实流动特征的问题,基于苏里格气田低渗透气藏压裂气井试井和实际生产资料,利用现代试井解释理论,研究了合理关井时间的界限及其计算方法。结果表明,当油井关井测压时间达到3倍地层径向流开始出现的时间后,利用此时的压力数据,解释地层参数和地层压力,其结果的误差小于5%,同时能较准确地判断边界类型。计算的理论曲线和霍纳法解释值非常接近,对于苏里格气田压裂气区而言,若预先知道某生产井地层有效渗透率值,可从理论曲线查出压力恢复试井的关井时间,否则,建议按照该井区地层有效渗透率,将不稳定试井测试时间定在以10d以上为宜。

Because the pressure buildup curves of fractured gas wells cannot reflect the boundary effect and the flow is not representative of real flow in the formation, this paper conducted a study on reasonable shut-in time and its calculation method based on well test and production data from gas wells in low-permeability reservoirs of Sulige gas field. It can be seen from the results, when the shut-in time triples the time for radial flow to begin, the interpretation errors of formation parameters and pressure are less than 5%, the boundary types can be accurately identified, and the calculated theoretical curves match Horner type curves very well. For fractured regions in Sulige gas field, the shut-in time can be determined from the theoretical curves if the formation effective permeability is known; otherwise, shut-in time longer than 10 days is recommended providing that the effective permeability is about 0.8×10-3μm2.