基于流固耦合理论的疏松砂岩地层稳定性评价

疏松砂岩油藏开发过程中,井眼形成、各种高强度开采措施的应用极易导致近井壁区域地层发生应力扰动、产生膨胀/压实变形,造成油井出砂,严重时井壁坍塌破坏,影响油井生产.应用连续介质力学理论,综合考虑流体渗流、储层变形、破坏等因素,建立了流固耦合形式的地层稳定性评价模型,采用有限元数值模拟技术定量分析开发过程中近井壁区域储层变形、有效应力变化及相应渗透性能变化.结果表明:井眼曲率、生产压差对地层稳定有显著影响,生产过程中可根据储集层岩性确定临界生产压差,在保持地层稳定的基础上提高产能.

Evaluation of the stability of unconsolidated sandstone formation based on liquid-solid coupling theory

In the development of unconsolidated sandstone reservoirs,the formation of wellbore and the application of various production measures will lead to the change of the formation stress near the wellbore,which will lead to well sand-producing even hole wall collapse.For this reason,the model for evaluating the stability of the unconsolidated sandstone reservoirs is established by applying the theory of continuum medium mechanics,in which the seepage of fluid and the deformation and collapse of solid reservoir are considered.The changes of the reservoir stress,deformation and permeability near the wellbore are simulated using finite element method.The simulation result shows that hole curvature and producing pressure drop are the main factors influencing the stability of the unconsolidated sandstone reservoirs near the holebore.Therefore,the critical producing pressure drop should be determined according to the lithology of the developed reservoirs.