Experimental Study Of Effective Seepage Flow In Low-permeability Area Of ??LWM Low-permeability Gas Reservoir

LWM gas reservoir is a marine carbonate rock gas reservoir.However,as the gas reservoir development and the knowledge of geological development characteristics deepen,it has gradually revealed that the damage caused by water intrusion to gas reservoir development has grown to be salient,which has become a major limiting factor in the development of gas reservoirs.On the other hand,the reserves of gas reservoir in the low permeability zone have been gradually exploited,and the low permeability zone plays a positive role in separating water bodies.However,the mechanism of low permeability reserves and the ability of water body flow are still unclear.Therefore,it is necessary to carry out in-depth research on the water flooding recovery rate and the water flow capacity of the low permeability zone in the LWM Moxi gas reservoir,which can then provide decision-making basis for effective measures for low-permeability reserves and the overall water control scheme.This paper mainly applies physical simulation technology.It will systematically test the low permeability water flooding recovery under different reservoirs with physical properties,and will determine the failure recovery degree of LWM low permeability gas reservoir,according to the water phase starting pressure gradient and water phase flow capacity test.It will be elaborately explained from the following four aspects:(1)The water phases starting pressure gradient and permeability test on six full-diameter cores different physical properties were conducted.(2)Under high pressure conditions(internal pressure 76MPa,fixed pressure 126MPa),four groups of full-diameter core stress experiments under water stress were carried out.(3)Two sets of core with different permeability grades and high pressure gas supply mechanism experiment on four cores with different gas production rates were conducted.(4)A numerical simulation study of planar gas supply was carried out.The main achievements are as following:(1)The relationship between the water phase starting pressure gradient and the core permeability was obtained.Then the data relationship between those two was established.As the core permeability decreases(physical properties reduce),the starting pressure gradient increases.When the permeability is less than 0.2mD,the starting pressure gradient increases significantly increases.When the core permeability is more than 0.2mD,the starting pressure gradient is very small,less than 0.01MPa/cm,and the change stays stable,with the water body flowing in the core.(2)The gas production per unit pressure fall decreases as the core pressure decreases,and the rate of decline in the middle and late stages increases.The water production rules of cores with different permeability are similar,and they are all unproduced water in the middle and early stages.After seeing water,the water production increases rapidly.The core with 10 times of water is more serious than the core with 5 times of water,and the recovery rate is lower.(3)Proper production reduction can prolong the life cycle of the gas well.In the stable production period,the yields in the high and low permeability areas are higher,but the high permeability areas are always higher than the low permeability areas.The contribution rate of gas production in high and low permeability areas is affected by both permeability and original reserves,and the distribution has little effect on the yield contribution rate of high and low permeability areas.