Staggering Locations for Oil Wells

The prevailing system of locating wells on a rectangular basis, as shown inFig. 1-A, has developed because of the exigencies of offsetting at boundarylines. When, however, a very large tract is being drilled, it is often possibleto abandon this inferior method for the superior arrangement known as"staggering," which is illustrated in Fig. 1, Band C. The advantages ofthe triangular over the rectangular method are evident from Fig. 2, computed onthe basis of one well to 10 acres (4 ha.). With the triangular system, no landis more than 409.4 ft. (124.8 m.) from a well, while with the rectangularsystem, 14,400 sq. ft. (0.33 acre or 0.13 ha.) lies more than that distancefrom a well. The purpose of this contribution is to assist the producer in planning thestaggering arrangement of wells. Some companies, in staggering wells, haveretained the same distance between the rows as between the wells in the row(Fig. 1-B), but to get equal distances between any two adjacent wells, which isdesirable in order to yield maximum drainage, the triangles must beequilateral, which necessitates the shortening of the distance between the rows(Fig. 1-C), making the quincunx arrangement, as customary in arranging tankfarms. The formulas for computing the distance between wells thus arranged werederived from Fig. 3, representing a well surrounded by the six nearest wells;the dot-dash line midway between the central and the surrounding wellsoutlines, the hexagon drained by this well. This hexagon consists of 12 righttriangles, each of the triangles having as its altitude one-half the distancebetween the wells (r), and as its base one-third the distance between the rows(y). The hexagonal area drained by each well therefore reduces to ry. AIME 061–54