Wireline Cable Dynamics and Wellbore Diagnostics in the Deepwater Logging Environment

The evolving complexity of deepwater wellbores has created new challenges and risks for wireline evaluation. Geometries and depths challenge the foundational assumptions of traditional depth control. As complexity grows, formation fluid gradients see scatter, sidewall cores have uncertainty about where they were taken, and mistakes have higher economic and environmental consequences. This study presents empirical data sets obtained from cable-mounted memory sensor packages during deepwater openhole logging operations. This is the first-ever study of wireline dynamics using downhole cable-mounted sensors. The sensors record wellbore temperature, pressure, triaxial accelerometer, and magnetometer data. An independent record of all downhole events like tool movements, depths, speeds, survey intervals, cable torques, and sticking events allows evaluation of hole and mud conditions, cable dynamics, and tool response throughout the logging operation. To date, cable-mounted sensors have been used to acquire data on 64 runs in 15 deepwater wells, covering a wide range of wireline services. These runs have particularly enhanced wireline formation testers and data quality control (QC). These data sets are contributing to new understandings of how depth control during wireline operations can be improved, but also provide practical wellsite data. One practical result of these studies is understanding downhole tool and cable movement compared to bulk creep corrections, as shown in Fig. 1. Fig. 1—The cable-mounted sensor package allows comparison of tool/cable movement to bulk creep corrections. Other practical results include the ability to confirm loss zones and to identify sticking or jarring events. The cable-mounted sensors output depth-based logs that encompass pressure, temperature, synthetic mud weight, cable rotation, casing-collar locator (CCL), inclination, and road noise, leading to the following outcomes: 1. Continuous Extrapolated Temperature Logs: These logs allow us to clearly identify mud column heating and cooling zones, with observable rates of change across consecutive runs and static temperature estimates from different reservoir packages to 10 ft TVD resolution. 2. Mud Column Integrity: Variations in mud column integrity have been detected following sampling operations, including the identification of a leaking packer during an attempted mini-frac. 3. Wireline Creep: Computed from accelerometer measurements after the winch has stopped on the station, wireline creep offsets of up to + 5 ft shallow have been identified. Anti-creep has also been identified, whereby the tool slows then stops before reaching the station, by up to – 8 ft deep. Creep is shown to be highly variable and may be the tip of a depth-discrepancy iceberg, driving scatter on fluid gradient plots. 4. Station Log Validation: Via continuous accelerometer data acquired during the entire pretest or rotary coring surveys, the winch technique and depth control can be validated (and improved if necessary). In deep, tortuous wells with high-viscosity muds, large and long tool strings may become decoupled from winch movements at surface, resulting in major depth errors. A traffic light system for station log depth quality has been established to drive logging procedures on a case-by-case basis. 5. Cable Dynamics: During incidents involving stuck tools, the sensors have been instrumental in confirming cable freedom, and they have recorded jar firing (or failure), providing valuable insights. 6. Torque Logs: These logs offer a downhole record of tension, torque, and rotation count during wireline operations. They supplement shop records and contribute to optimizing cable maintenance and inspection regimes. 7. Road Noise Logs: These logs identify cable contact zones, which may be used to assess wireline casing wear zones before they happen. As we continue to better understand and utilize these data sets, we can anticipate practical and academic improvements that will enhance wireline formation evaluation and benefit the industry.