Abstract
The WXSO (fig.1) is a profiled wireline standoff which records a unique dataset allowing analysis of wellbore conditions and cable dynamics downhole during wireline logging operations. Typically, the WXSO is attached to the cable ~ 50ft above the cable head and its response accurately tracks the logging tool movements below. This paper discusses the data acquired, examines the various analyses and their applications, and the value delivered by this data. To date, WXSO has logged over 65 runs on 15 deep-water wells with a comprehensive range of wireline services.
The WXSO is approximately ten inches long and three inches in diameter. It houses a miniature multi-channel memory logging package which acquires pressure, temperature, and tri-axial acceleration & magnetometer data. The WXSO logging duration is limited to ~6 days, sufficient to cover most wireline services. The data is time-depth converted post-run to yield the following log deliverables:
Run summary logs: identifying key events downhole (logging times, depths, speeds, survey intervals, and any sticking events).
Depth-based logs of borehole conditions and cable dynamics: pressure, temperature, synthetic mud weight, cable rotation, CCL, inclination and road noise. This data provides an overview of the operation, together with detailed logs for further interpretation.
Continuous extrapolated temperature logs: mud column heating and cooling zones are clearly identifiable, with rates of change observable run by run. Static temperatures of different sand packages may provide valuable data points to aid reservoir description and interpretation.
Mud column integrity log: variations (lower density zones) have been identified after clean-up and sampling
Wireline depth analysis for stationary surveys: computed from WXSO accelerometers after the winch has stopped on station.
Potential station log depth errors from – 8ft to + 5ft have been identified.
Where the WXSO indicated large depth errors during sampling, the tests were repeated, utilising the computed creep offset, with resulting successful test data.
Cable dynamics: during stuck tool incidents the WXSO has been used to confirm whether the cable was free; jar firing (or failure) has been recorded and confirmed by WXSO using computer generated imagery (CGI).
Rotation logs: provide a down-hole record of cable rotation count during the wireline operation, which can supplement cable records to optimise cable maintenance and inspection regimes.
Road Noise Logs; identifying cable contact zones for potential wireline casing wear.
This data provides diagnostics for wireline data packages to improve data QC, decision making and operational procedures, allowing better planning and mitigations for future operations.