Progressive displacement of residual water past shut-in wells preparatory to tertiary oil recovery

摘要

In the oil-bearing formation wherein primary production has been exhausted and secondary recovery by waterflooding is exhausted or about exhausted, the residual brine is removed by progressive displacement. In this displacement a centrally disposed injection well or, preferably, lineal injection wells are utilized for the initial injection of preflush fluid with the immediately adjacent production and/or injection wells being shut in. After a specified slug of preflush has been injected, a series of chemical slugs is injected followed by drive fluid. After displacement of the residual brine has been effected out past the adjacent shutin wells, as evidenced by the arrival of the preflush, they are utilized as production wells. After oil sweep to these wells is complete, they are used as injection wells and the procedure is moved another step outward.