Research On Formation Damage Mechanism In Yaoyingtai Area

Though the basic causes of formation damage are known, given a reservoir, we must analyze the idiographic reasons of it due to the variety of geology and formation condition.In this paper, according to standard experiment program, systemic analysis of reservoir sensitivity of Yaoyingtai oilfield is carried out, the result is as following:Water sensitivity (strong medium), salt sensitivity (medium), alkali sensitivity (medium), velocity sensitivity (weak).Based on sensitivity analysis, a systematic study on formation damage mechanism is carried out, which indicates that the main reason causing Yaoyingtai area formation damage is the liquid phase damage, and the solid phase damage is very little; drilling fluid filter loss,especially high temperature and high pressure filter loss is very big to the reservoir permeability influence; along with drilling fluid pressure enlargement, the resumer of permeability tend to drop, and filtrate depth of penetration increase; along with drilling fluid harm time enlargement, the resumer of permeability tend to drop, and filtrate depth of penetration increase, but the change scope is not big;the resumer of drilling liquid permeability of DB27 well tend to be the highest,next is Daqing amphoteric complex ion drilling fluid, the resumer of drilling liquid permeability of DB38 well to be the lowest.On the basis of traditional"2/3"bridging law, this paper sets up fractal theory to optimal selection of temporary blocking agent.