Smart Entry into Multilateral Wells with Coiled Tubing Fiber Optic Telemetry

Abstract

Verifying that conventional coiled tubing (CT) has entered the correct lateral of a multilateral well can be a time-consuming and tedious challenge. While passing the kickoff point (KOP), surface pressure sensors may not clearly identify that a hydraulic knuckle joint has entered the lateral. To verify which lateral has been entered, the CT must be run-in-hole (RIH) to tag the unique total depth (TD) of the lateral. It can be difficult to prove that the correct lateral has been entered if the TDs for two laterals do not differ significantly. If the CT tags before or after the expected TD is reached, then the operator must pull out of hole (POOH) and repeat this process. This paper presents an improved method for detecting which lateral has been entered shortly after passing the KOP by using a real-time, fiber optic cable (RTFO) bottomhole assembly (BHA). The RTFO BHA is equipped with sensors for gamma radiation (GR), tool inclination, tool face, casing collar locator (CCL), internal and external pressure, and temperature. These readings enable the operator to use the CCL and gamma detector to correlate to the desired lateral’s pipe joints using an existing CCL/GR log. The tool face reading theoretically predicts which angle the knuckle joint should be indexed. The internal pressure sensor provides clear indication of pressure changes when a hydraulic knuckle joint has entered the lateral and the inclination sensor verifies that the inclination of the BHA matches the inclination of the desired lateral. This paper discusses two dual-lateral water injection wells; the TDs of the laterals in the first well were equal, with no trait that conventional CT would be able to distinguish. In addition, the inclination of each lateral was very close to the other, making the difference of pipe weight, read from the surface, not significantly different enough to verify which lateral had been entered. However, with the RTFO BHA, the correct lateral was easily entered and verified, significantly reducing time, risk, fluids, and CT pipe fatigue, while providing assurance that the stimulation fluid was accurately placed. This paper describes the first time that a flow-through gamma, inclination, tool face sensor module was deployed to accurately enter, identify, and stimulate a casedhole multilateral well without cycling the CT at the KOP, and without relying on tagging TD to confirm that the BHA is inside the desired lateral. The new process proved to be a better, more cost effective, and efficient way to stimulate multilateral wells. This solution can be used by operators to extend the life of their mature fields.