Abstract: One of the crucial issues in reservoir engineering study is how to choose pattem well spacing in order to reach the highest recovery and optimal economic eficiency by waterooding process for field development project designing and well pattem infill or adjustment. Based on the relationship among recovery, well spacing density and injection-to-production-wel ratio given by Reference [1], integrated with other methods such as economic evaluation and injection-production balance analysis, etc., this paper proposes a new method for determination of .reasonable well spacing density and injection-to production-well ratio in waerlooding field. The case analysis and calculation from QL oilfield shows that there are additional potentials on the primary density and ratio under the rising of current oil price.

Key words: field development, well spacing density, injection-to-production-well ratio, recovery, economic evaluation