Research Of Porosity And Permeability Change Rule At The Different Flooding Development Stage For NP Oilfield

The article is intended for the following problems: the injection pressure of NP oilfield ishigher at present and the research about reservoir porosity, permeability change rule at thedifferent flooding development stage is lack, and regulating reservoir development projectlack of basis and production difficult is bigger and bigger.On the basis of the results ofassessment for reservoir mineral composition of NP oilfield, the potential susceptibility ofreservoir is evaluated by analyzing the potential velocity sensitivity, water sensitivity, acidsensitivity and alkali sensitivity. The result shows: there are montmorillonite, kaolinite, illite,chlorite, montmorillonite and illite interbeds in different extent in all rock sample. The mainpart of D1and D2block are montmorillonite and illite interbeds, montmorillonite andkaolinite, and there is a certain degree velocity sensitivity, strong water sensitivity, potentialacid sensitivity and alkali sensitivity.The evaluation about velocity sensitivity, water sensitivity, acid sensitivity and alkalisensitivity for NP oilfield is done by doing susceptibility evaluation experiment. The resultshows: the velocity sensitivity degree is middle and the critical flow is0.25~0.5ml/min for D1block; water sensitivity degree is low~strong water sensitivity and critical degree ofmineralization is about7500mg/L.Aid sensitivity degree is strong;alkali sensitivity is mediumweak. The velocity sensitivity degree is medium weak and the critical flow is1.0ml/min forD2block;Water sensitivity degree is medium water sensitivity and critical degree ofmineralization is about8000mg/L.Acid sensitivity degree is medium;Alkali sensitivity isweak. At the development stages, the hurt about susceptibility to the reservoir should beavoided.According to the reservoir mineral composition and the experimental result aboutsusceptibility, the porosity and permeability change rule at the different flooding developmentstage is researched. The result shows: in the D1block, with the water injected with differentmultiples of pore volume increase continually, the medium porosity and the diameter ofchannel is increase, hydrophily of reservoir becomes strong and the permeability of reservoirhas the trend of increasing. In the D2block, with the water injected with different multiples ofpore volume increase continually, the medium porosity and the diameter of channel isdecrease, hydrophily of reservoir becomes strong and the permeability of reservoir is decrease.The changes of the average ligancy and pore structure for core are small.