Abstract: The calculation of well-controlled area is the foundation of geological and remaining reserve evaluation in the oilfield development and adjustment. As in the case of discrete points with variable well spaces, a new kind of edge pivoting boundary searching algorithm with angle identification and variable searching step is promoted. The neighborhood of the current boundary point is firstly determined based on a proper searching step. The corresponding angles of those points in the neighborhood are calculated and sorted, and the next proper boundary point is determined. Based on the identified boundary wells, the general boundary enlarging method is presented. And finally the well-controlled area calculation method is given. The algorithm has the advantages of easy-to-use and high efficiency. It could be effectively used to identify the convex and concave characteristic in a discrete point set with variable point spaces. The method has been applied in the geological reserve recalculation and remaining reserve evaluation in SZ oilfield, which improves the working efficiency more than 5 times, obtains an accuracy of 2.7% in the recalculation of geological reserve and shows a good result of application.

Key words: edge pivoting, boundary, enlarging, injection-production well system, well-controlled area