Research on Effective Development Methods for Ultra-thin Heavy Oil Reservoirs

 

The Saertu heavy oil reservoirs in the WE block of Daqing are low-abundance ultra-thin heavy oil reservoirs.Only small -scale steam stimulation field tests have been carried out before.The degree of development is low，and the economic benefits are not up to standard，so an effective development technology system is not formed.The well pattern and effective producing mode of different sand body scales are unclear.

 

There-fore，based on the flow characteristics of reservoir fluid, core flooding experiments, numerical simulation, and economic evaluation research are conducted to compare and analyze the development effects of elastic developmen, hot water flooding, steam stimulation，elastic development to steam stimulation, and steam flooding. The optimization design method of development methods and the well patterns of ultra-thin heavy oil reservoirs are established. The well-controlled reserves of vertical and horizontal wells under different channel sand body scales are evaluated，and the technical and economic well spacing of varying development methods is calculated.The results show that the effective period of elastic development is 240 to 300 days, the recovery rate of elastic development to steam stimulation is higher, and its internal rate of return is the highest. The research results are used to guide the preparation of a well development plan for the block in four phases, 493 development wells (155 horizontal wells) are designed with a designed productivity of 32.59×104 t.

 

The horizontal wells were deployed in areas where the river width exceeds 250m and the effective thickness exceeds 2.3m. The vertical wells were deployed in areas where the river width is less than 250m and the effective thickness exceeds 2.7m. A well spacing of 140m is designed, and the development method of early elastic development and later steam stimulation is adopted. So far, 292 wells have been drilled and put into production, with a cumulative oil production of 32.7 ×104 t, achieving increased reserves, construction of production, and oil production in the same year.