A Study On Sanding Mechanism And The Change In Flow Field In Unconsolidated Sandstone And Heavy Oil Reservoir Of Block Huan 127

Block Huan127 loates at south-west of Huanxiling oil field which is on the western slope of Liaohe faulted basin. The block cut by two faults is a nose-like structure sloping down south-east. During the development of the block, sanding and fines migration in the oil reservoir is a serious problem. After a long term development of the kind of reservoirs, sand particles release and fines migration in the oil formation will occur due to water flooding for long time. Water sensitivity and sanding problem will lead to the change in porosity and permeability of reservoirs. The serious sanding problem occurred in the vicinity of wellbore will influence oil production. The sanding problem occurred in the formation between injection well and production well will form water flow channels between injection and production wells and leads to reduciton in sweep volume and displacement efficiency. Sanding problems not only cause case damages and high costs for well operation, but also lead to more heterogeneity of formation and more difficulty in improving oil recovery. The water sensitivity of clay is also one factor to change percolation field. Clay swell caused by incompatible injection water and formation water may lead to the reduction in porosity and permeability of oil reservoirs. The causes leading to the changes in properties of percolation field lie in not only reservoir rock facors, but also operation factors such as fluid flooding and thermal prodution. Comprehensive study on the changes caused by oil production in the properties of percolation field has significance for describing remaining oil and improving the recovery of Block Huan 127.By comprehensively using the approaches such as theoratical study, physical simulation in lab, mathematical simlation, and refering to multi-data from oil fields, this paper combines with oil formation physics, oil reservoir engineering, fluid mechanics in porous media and oil reservoir numercial simulation and conduct the following researches.(1) The sanding mechanism of heavy oil and unconsolidated sandstone resvervoirs was studied in this work.(2) The methods to diagnose sanding problems and its effects on the percolation fields in this kinds of reservoir was presented.(3) Theory of modern percolation mechanics and applied mathematics were used to present a percolation mathematical model considering the change in the formation parameters in heavy oil and unconsolidated sandstone resvervoirs.(4) The numerical solution method to solve the percolation mathematical model was chosen and the simulator suit for simulating heavy oil and unconsolidated sandstone resvervoirs was written in computer language Fortran. (5) The changes in the percolation field parameters and their effects on oil production performances were studied by oil field simulaion on the simulator.Achievements and Understandings are obtained from this work:(1) Colloidal force hydrodynamic force are the major causes stimulating sand particles release and migration in oil formation during oil development.(2) Sanding and fines migration and clay sensitivity are two main factors leading to the changes in percolation field during oil production.(3) multi-period Huff and puff of a well causes to serious sanding problems in the vicinity of wellbore and leads to dramatic change in percolation field.(4) Sanding problem caused by steam flooding will leads to strong heterogeneity and high permeability bands, which leads to low flooding efficiency and increase the difficulty in oil recovery.(5) The foundation of mathematical model of heavy oil and sanding percolation and developed simulator improve the prediction accuracy to simulate heavy oil and unconsolidated sandstone resvervoirs.