Study on the influence of injection/production type and well pattern and spacing on producing degree of thin and poor layers

摘要

Daqing Oilfield has already entered the period ofhigh water-cut oil production, and currently the targetwithin the oilfield is thin and poor reservoir layers, whosethickness is less than 0.5 m, and it has very low permeability. These layers also have complicated pore structureand poor developmental benefits because of the low permeability, yet several million tons of remaining reservesexist in these low-permeability, poor and thin layers. Thispaper analyzed the influence of several factors on thedegree of production from these thin and poor layers,specifically focusing on the injection/production type andwell pattern and spacing, in order to provide guidance fordevelopment of thin and poor reservoir. Two producingmodels were used to analyze the influence of injection andproduction type on the production degree of these thin andpoor layers: water injection into thick layers, and producingfrom the thin layers, and vice versa. Also, the effects ofwell spacing and pattern under different pressures wereanalyzed by calculating the effective producing coefficientand areal sweep efficiency based on the flow tube modeland oilfield examples. The results show that the best way todevelop a thin and poor reservoir is thin injection and thickproduction type and that a reasonable well spacing rangeshould be within 200 m. Beyond this 200 m spacing, it isdifficult to increase production, even if the reservoir pressure is significantly increased.