基于网络模型的油藏优势通道形成微观机制

基于实际疏松砂岩油藏优势通道发育特征,建立了考虑微粒运移及附加压力损耗的动态孔隙网络模型,对控制优势通道形成的微观因素进行了研究,明确了不同孔喉结构及工作制度下优势通道形成规律。研究结果表明:在常规网络模型基础上,针对孔喉中微粒脱落、运移、堵塞等行为建立数学模型,并考虑由优势通道引起的附加压力损耗,最终建立可模拟优势通道微观发育的网络模型;通过对比所建网络模型与实际优势通道发育特征,验证了网络模型的正确性,初步明确了孔喉半径动态变化与优势通道规模的关系;具有孔喉半径较大、配位数较多、形状因子较大等初始孔喉特征的储层,更易形成优势通道,驱替压差对其也有较大影响,总之,微粒在孔喉中堵塞与疏通所形成的平衡关系对优势通道发育有重要控制作用。该研究可为此类油藏储层伤害研究及注水开发调整提供一定指导。

MICROSCOPIC MECHANISM OF THE DOMINANT FLOWING PATH FORMATION IN THE OIL RESERVOIR BASED ON THE NETWORK MODEL

Based on the developed characteristics of the dominant flowing paths in the actual unconsolidated sandstone oil reservoir,the dynamic pore network model was established considering the particle migration and additional pressure loss,and moreover the studies on the microscopic factors of the formation of the paths were conducted,and then the forming laws of the paths were made clear under different pore structures and operational systems.The research results show that on the basis of the normal network model,the mathematical model has been established in the light of the conditions of the particle fall-off,migration and block in the pores and throats considering the additional pressure loss,finally the network model has been built to simulate the microscopic development of the paths;through the comparison between the new-established model and actual paths,the validation of the model is conducted and the relationships between the dynamic changes of the pore radius and path scale are preliminarily verified;the reservoirs with the original pore characteristics such as pretty bigger radius,much more coordination number and more larger shape factor are prone to form the dominant flowing paths.And moreover,the displacement pressure plays an important role in the process.Finally,the balancing relationship between the blockage and communication of the particles in the pores and throats exerts an important control on the path development and growth.These studies can provide a certain references for the formation damage research and development adjustment of the water flooding.