Targeting Horizontal Wells—Efficient Oil Capture and Fracture Insights

Abstract

Summary Horizontal well targeting is often a greater challenge in massive, fractured carbonates than in low-productivity, poorly connected, and relatively thin reservoirs. This paper discusses methods to target horizontal wellbores in three-dimensional space to both confirm the fracture interpretation and establish high-efficiency oil capture. Several well examples are presented to illustrate the targeting objectives and the resulting well performance. Early in the program, the horizontal drilling objectives sought to maximize the lateral length in a direction determined by offset well productivity; the sample philosophy as is used in matrix-dominated reservoirs. Analysis of these results and employment of methods presented in this paper indicate profit can be maximized by drilling to a specific target to intersect a fracture trend at an optimum elevation instead of concentrating on maximizing length of lateral. Intervals of rapid penetration, lost circulation, and/or bit slides, along with cutting sample compositions, provided insight for confirmation and extension of the fracture network interpretation. The width of disturbance and degree of fracturing observed along interpreted fracture trends are valuable data for improved fracture network interpretation and computer simulation. Both the elevation and number of fracture branches encountered are significant strategic planning issues for oil recovery from unconfined oil columns in a massive carbonate system. Results from a large number of horizontals indicate significant productivity increases are achieved by proper targeting of laterals into major fracture features.