Distribution Of Oil-water And Effective Development Of A Oil Field Of Daqing Oilfield

The oil area of A oilfield is N1km2,and proved unused reserve is N2×104t.There are total 150 wells in this region including thirty testing wells.Fifteen wells of testing wells achieved commercial oil flow,three wells had low productivity and twelve produced water,which shows desirable development potential.However,the reservoir was thin and unfavorable,the production of testing wells varied a lot and oil-water distribution was complex.What's more,there were both two-dimension seismic data and three-dimension seismic data in this region.Therefore,in order to find out the structure,reservoir and oil-water distribution,researches have been carried out to further study geologic characteristics,which can provide foundations for the appropriate development.The structure of north work area was high in the north and west while low in the east and north.There were a lot of faults which stretched mostly SN and NNW direction.The work area has been cut into two relatively separate blocks by step-fault zone.The reservoir of north work area was mainly lithologic and fault-lithologic whose oil-water interface was not unified.Oil-bearing series were mostly on the upper part of the structure while oil-water reservoir was on the lower part of the structure.The reservoir of south work area was lithologic where there were oil beds,poor oil beds and oil-water beds.Local reservoir showed oil bed interbedded with water bed in PI 2 reservoir caused by the lithologic control.Favorable region has been predicted according to the study above,and favorable oil area has been chosen in the unproved reserve region.The study on feasibility of horizontal well has been carried out which indicated that the PI2 and PI4 would be targeted.The horizontal section has been optimized to as long as 700 m and parallel to fissure.The butt end and toe end should be avoided perforating 130 m from each end.It has been calculated that economic limit well spacing was 247 m and well spacing has been optimized to 300 m.Square five-spot pattern has been decided for the vertical wells and well spacing and row spacing was 300 m and 150 m respectively.It has been decided that injecting with vertical wells while producing with horizontal wells for horizontal wells,while advanced water injection has been adopted.