New Logging-While-Drilling Ranging Technique for SAGD: Theory and Experiment

摘要

In a heavy oil production steam-assisted gravity drainage (SAGD) project, two horizontal wells were separated by only a few meters. The separation had to be kept parallel to enable steam to be injected from one well and oil to be produced from the other twin well located below. In general, the currently practiced techniques rely on wireline technology to position the wells; in many cases, the technique requires access to the existing well in SAGD operations. This paper presents a novel technique for locating the relative position of one well with respect to another by using a rotating azimuthal logging-while-drilling (LWD) electromagnetic tool. With this technique, the relative position between a well with a rotating LWD electromagnetic tool and casing in an adjacent existing second well can be determined in real time. Consequently, the relative position and the relative distance between the two wells provide the field engineer with calculated inter-well spacing and direction to maintain the two wells parallel and spaced within a certain distance apart. This paper discusses and explains the fundamentals of the new LWD ranging technique. Several cases were modeled and compared with experimental data collected in a water tank with a conductive casing. The experiments successfully validated the computed responses. The casing position and distance to the LWD tool were successfully determined. This new LWD technique presents a ranging method alternative to the existing wireline technique and can be successfully used in a SAGD application.