一种“压力衰竭”假象的识别与对策

D油田的第一口井DST5压力曲线显示可能存在"压力衰竭",解释过程中边界模型选为多条不渗透边界,这与本地区的地震、地质认识相矛盾。从地震和地质的研究成果、PPD函数和区域压力系数三个方面分析,否定了不渗透的边界模型。研究表明,测试资料所显示的测试过程中似乎出现了"压力衰竭",事实上只是一种假象。从岩性物性和初开井时间两个方面分析了造成"压力衰竭"假象的根本原因。建议试井解释要注重与其他学科相结合。此类储层的测试,应该采取延长初开井时间、降低泥浆比重、采用井下关井等措施,避免出现"压力衰竭"的假象。

A Kind of False “Pressure Depletion” Identification and Countermeasure

DST5 pressure derivative curve of the first well in D field shows that "pressure depletion" probably exists during the test,so many impermeable boundaries are selected as the outer boundary in well test interpretation.But seismic and geology data show that there weren’t any bounded boundary.Impermeable boundary model is denied based on the three aspects of PPD function,pressure coefficient and the study of seismic and geology.The reason that false "pressure depletion" appears is analyzed from initial flow time,lithology and physical property.The research result shows that current well testing data cannot prove pressure depletion appears but a false "pressure depletion" phenomenon.Well testing interpretation should be integrated with other subject.For such formation,longer initial flow period,lower mud density and down-hole shut-in method should be chosen to avoid appearing false "pressure depletion".