基于地质力学模型的X气田防砂临界生产压差预测

Predicting the Critical Differential Production Pressure of Sand Prevention for X Gas Field Based on Geomechanics Model

摘要: X气田多口气井出砂，为最大限度地消减出砂危害，建立气井防砂地质力学模型，预测气井临界生产压差。X气藏为胶结程度较好的砂岩储层，其破坏机理遵从Griffith准则。依据弹性理论，通过近井地带储层岩石应力分析，导出能够避免气井出砂的最大允许井底流压计算公式。利用测井数据，计算储层不同深度的孔隙压力、主地应力，以及储层岩石的抗拉强度等参数，使用临界生产压差计算公式计算储层不同深度的临界生产压差。考察X气田若干口气井的出砂情况，结果表明当气井实际生产压差小于计算出的临界生产压差时，气井没有出砂；当气井实际生产压差大于计算出的临界生产压差时，气井出砂。该防砂临界生产压差预测方法可有效指导X气田气井工作制度的制定，消减气井出砂危害。

Abstract: Many wells in X gas field produced sand. Geomechanics model was founded and critical differential production pressure was predicted for avoiding the harm induced by sand production. The sandstone in X gas reservoir has a good cementation, and the fracturing mechanism complies with the Griffith criterion. The computational formula of the maximum bottom hole flowing pressure permitted for eliminating sand production was derived through elastic theory and stress analysis of the sandstone around well hole. The pore pressures, principal ground stresses, tensile strength, etc., in different depth of gas reservoir, were calculated by utilizing logging data. And the critical differential production pressures in different depth of gas reservoir were computed with these parameters. The sand production situations of several gas wells in X gas field were investigated, which indicated that the wells would not produce sand while the practical production pressure was less than the critical differential production pressures and the wells would produce sand while the practical production pressure was greater than the critical differential production pressures. The prediction method of the critical differential production pressure for preventing sand production of gas well is capable of guiding the working system of gas wells in X gas field and weakening the harm of sand production.