压力衰竭下疏松砂岩出砂临界生产压差预测方法

Critical Drawdown Pressure of Sanding Onset for Unconsolidated Sandstone Reservoirs when Reservoir Pressure Depleted

石先亚 黄侠 史景岩 赵广渊 徐丽媛

SHI Xianya HUANG Xia SHI Jingyan ZHAO Guangyuan XU Liyuan

中海油田服务股份有限公司, 天津 滨海新区 300459

China Oilfield Services Limited, Binhai New Area, Tianjin 300459, China

海上油气藏多采取衰竭式开发，开发后期储层压力衰竭导致岩石应力状况变化，致使弱胶结疏松砂岩储层严重出砂可能性增加。为了有效做好出砂预测，针对衰竭式开采弱胶结疏松砂岩油气藏，同时考虑储层压力衰竭对地应力影响，基于井壁处岩石应力状态分析，引入岩石骨架破坏Mogi-Coulomb准则，建立出砂临界生产压差CDP模型，给出一种适用于海上储层压力衰竭开采生产井全生产周期出砂预测方法，并结合油田实例，计算并绘制出F-1井全生产周期出砂临界生产压差图版。研究表明，初期出砂临界生产压差较大，随着地层压力逐渐衰减，临界生产压差逐渐降低，至临界储层压力时，由于地层出砂不能生产，需要补充地层能量或者采取防砂措施，预测结果与现场出砂情况相符合，研究成果能为易出砂井配产提供指导意义。

Offshore reservoirs are generally exploited without energy supplement, and reservoir pressure depletion will cause rock stress changes which results in an increasing likelihood of serious sand production in the unconsolidated sandstone reservoir. This paper aims at offshore unconsolidated sandstone gas reservoirs, analyzes rock stresses of the borehole wall with impact of reservoir pressure depletion on in-situ stresses. Combining with fully-polyaxial rock failure criterion Mogi-Coulomb, a new sanding Critical Drawdown Pressure (CDP) calculating model. Furthermore, an applicable sanding prediction method for pressure depleted gas reservoir in well whole life cycle is proposed. The model was applied in F gas reservoir, the chart of sanding CDP for Well F-1 in the whole production life cycle is plotted. The research results indicate:initially, the sanding CDP is relatively large; with formation pressure depletion, CDP is reduced step by step until depleted to the critical reservoir pressure, and sand will be produced no matter how small the drawdown is. The research outcomes are consistent with actual oilfield production situation, which can provide some theoretical supports for sand production gas wells.

10.11885/j.issn.1674-5086.2019.08.12.01