Experimental Study Of Particle Plugging In Fractured-cavernous Reservoir

Sinopec Tahe oilfield is located in the northern Tarim Basin of Xinjiang province,which reservoir space are holes,fractures and caves.Fractures are the main seepage channel over the throat in reservoir.However,high permeability fractures cause serious water invasion in the producing wells,and the injection water is difficult to spread to the reservoir of high oil content,which leads to the decrease of the final recovery rate.At present,the density of particle plugging used in the field is large and the cost is high.Therefore,it is of great significance to optimize the evaluation of the low-density and low-cost particle plugging system for improving the development effect of the flow channel.This paper collected the 5 kinds of commonly used field particle plugging agent,and studied thier density,deformability,oil-water selectiveity and plugging rule.Finally,a plugging agent system suitable for reservoirs in Tahe is selected.As a result,the following main results and recongnition has been achieved:(1)The density of rubber particles 12 nd and 15 th is close to formation water,and it can soften and deform at high temperature and have poor selectivity for oil and water.The crack model plugging test shows that the sealing effect of 5mm and 9mm is good,and the price is about 3000 yuan per ton.Polystyrene particles have small density,oil-water selectivity,and viscoelastic particles softening at high temperature.Using it or combining with other particle has good plugging effect,and the price is about 5000 yuan per ton.(2)Two different fractured models of stainless steel uniform and trapezoidal glass models were designed.Experimental results that: the location of particles plugging in the same crack depends mainly on the particle size.The greater the particle mass fraction,the higher the plugging efficiency in fracture.The addition of fiber in particle will increase the plugging efficiency and increase the sealing pressure obviously.(3)The matching relationship between particle size and fracture width was studied,the minimum mass fraction of particles with different particle sizes needed to seal different slit width was found.On the basis of this,the fitting formula of different particle size particles and gap width was fitted and the fitting effect was good.The general matching chart based on the fitting formula had guiding significance for the field construction of particle profile control in Tahe oilfield.