Effectiveness Well Integrity Management for Casing Leak Detection Utilizing Temperature Profile in Offshore Oil Field

Abstract

As part of well integrity and safety campaigns in offshore fields, downhole Temperature surveys were obtained as record of temperature values measured with respect to depth steps (logs) in a well. The downhole condition for each well is an essential factor to determine the well status and to prevent a serious reservoir damage if there is a cross flow phenomena. Therefore, temperatures measurement at varies depths were used to establish the temperature profile which is reflecting the downhole condition. Several oil wells are subject to be evaluated through the campaigns in terms of downhole integrity especially casing leaks problems. Due to long period of shutdown for the field, close monitoring surveys with more focus on the aged wells are required to avoid flow behind pipe and cross flow phenomena, which will lead to the formation damage and production losses. The applied approach which is related to Well Integrity Management (WIM) started by creating a baseline in terms of temperatures profile for each well at cost effective time-lapse. The reference is a geothermal gradient log recorded in shut-in condition. Slickline operations were performed to execute the bottomhole temperature surveys. The temperature profile interpretation added great value in terms of confirming the wellbore integrity and detecting anomalies such as a sustained casing pressure and casing leaks. Effectiveness Well Integrity Management (WIM) included the methodology of monitoring, detecting, and localizing leaks phenomena across shallow aquifers was used to extend the well operability life. The approach was implemented on several field cases in order to detect casing leaks in offshore oil wells. A capture of temperature anomalies were found with a clear deviation from the baseline gradient. Based on the evaluation results, many of anomalies were related to the entry of fluids into the borehole. However, there were some cases indicated that the fluid flow was upward. It is noted that the temperature was affected by the type of occupied fluid into the outside casing and by the type of movements. As a result, the temperature profile was sensitive to not only the borehole condition but also the formation type and the casing-formation annulus. The paper covered field wells completions evaluated and interpreted their temperature profiles to capture the temperatures anomalies leading to casing leak, flow behind pipe, and a cross flow phenomena. The approach applied further investigation by integrating technique with other integrity surveillance logs. In addition, the results from the workover operation with the remedial actions shared in order to validate the findings.