Research On The Formation Sensitivity And Damage Mechanism Of Hailaer XiSan Block

The reserves of low permeability oil field is rich in our country, according to incomplete statistics, the unproducting reserves of low permeability oil field account for over fifty per sent of the total unproducting reserves in our country. The output of low permeability oil field is increasing year by year. Though the geologic condition of low permeability oil field is bad and it is difficult to be developed, the rich reserves of low permeability oil field are getting more and more notice with high speed economic growth and more and more demand for oil product in our country. The Hailaer oil field belongs to mesoporosity and low permeability oil field. It's pore configuration is complex and contains much clay. To evaluate the sensitivity of the formation exactly and analyse the damage mechanism of the formation will supply the reservoir engineering with valuable data.This paper analyzed type and quantity of clay mineral according to the characteristic of Xisan block in Hailaer oil field. Reference to formula reduction of critical condition of particle starting, calculate the condition of rate sensitivity happening. It can direct the experiment. Build on the analysis of clay mineral, the sensitivity experiment is conducted.The sensitivity of Xisan block are as follows: water sensitivity (high),salt sensitivity (medium to high),alkali sensitivity (midium),rate sensitivity (medium). On the base of departmental standard, the kerosene rate and rising salinity experiment were added. The test result is more reasonable for field actual condition. Recommended water intake per unit thickness was given.The formation damage mechanisms was researched in the paper, the main reason of leading to the formation damage is adventitious fluid invading, it means the main damage way is liquid phase damage. The solid phase damage is little.According to the distinguishing feature of Xisan block, existing drilling fluid system was improved, no invasion protection agent JYW-1 was added in the drilling fluid, made it convert to ultra-low permeability drilling fluid. The sand bed filter loss was lowed a big margin. The permeability recovery rate was raised and got good formation protection effect.