1.
2.
3.
4.
In addition to incremental production and improved reserve recovery, these worldwide CT drilling campaigns are yielding con- tinual improvements in wellsite safety and operational effi ciency.
Accessing Lateral Well Branches
This prevented remedial operations on individual laterals and precluded effective reser- voir management. Schlumberger developed the Discovery MLT multilateral tool to selectively access all types of multilateral junctions using standard CT equipment. The Discovery MLT tool provides CT-conveyed cleanout, stimulation, cementing and well- logging options for wells with previously inacces- sible junctions and for multilateral completions without specialized diverter equipment. This acid-resistant tool operates solely on pressure and fl ow. Reentry operations are performed in a single trip into the wellbore. A fl ow-activated bent-sub controls tool opera-
In the past, reentry access to sidetracks from an openhole main wellbore (TAML Level 1 junction) or openhole drains and dropoff lateral liners in a cased well (TAML Level 2 junction) was not possible.21
tion (above). Initially, the tool is indexed through 360° to establish the lateral orientation. After repeating this process to confirm the junction location, a pressure-telemetry signal to the surface confirms lateral access. Zakum Development Company (ZADCO) applied this
> Multilateral well interventions. The corrosion-resistant Discovery MLT system includes a controllable orienting device to rotate the tool and an adjustable bent sub. Wellbore junctions are located by moving the tool, which is actuated by uid ow, up and down across a target interval (1). When uid ow exceeds a threshold rate, the lower tool section changes from straight to bent (2). Each actuation cycle rotates the tool 30° , producing a surface-displayed pressure pro le that con rms lateral orientation (3). This system allows coiled tubing to selectively access any type of lateral for well cleanouts, logging, perforating, stimulation and cementing (4).
17. Mathes RA and Jack LJ: “ Successful Drilling of an Underbalanced, Dual-Lateral Horizontal Well in the Sajaa Field, Sharjah UAE,” paper SPE 57569, presented at the SPE/IADC Middle East Drilling Technology Conference, Abu Dhabi, UAE, November 8– 10, 1999.
18. Suryanarayana PV, Smith B, Hasan ABM, Leslie C, Buchanan R and Pruitt R: “ Basis of Design for Coiled Tubing Underbalanced Through-Tubing Drilling in the Sajaa Field,” paper SPE 87146, presented at the IADC/SPE Drilling Conference and Exhibition, Dallas, Texas, USA, March 2– 4, 2004.
19. Pruitt R, Leslie C, Smith B, Knight J and Buchanan R:
“ Sajaa Underbalance Coiled Tubing Drilling ‘ Putting It All Together’ ,” paper SPE 89644, prepared for presentation at the SPE/ICoTA Coiled Tubing Conference and Exhibition, Houston, Texas, USA, March 23– 24, 2004.
20.Wright HJ, Aristianto B, Gan RG, Jenie JR and Kyaw HA:
“ Coiled-Tubing Drilling Reentry: Case History from East Kalimantan,” paper SPE 89632, presented at the SPE/ICoTA Coiled Tubing Conference and Exhibition, Houston, Texas, USA, March 23– 24, 2004.
21. Multilateral wells are classi ed according to de nitions established during the Technical Advancement of Multilaterals (TAML) Forum held in Aberdeen, Scotland, July 26, 1999 and recently updated in a July 2002 proposal that was approved in 2003. These standards characterize wellbore junctions as Level 1, 2, 3, 4, 5 or 6 based on degree of mechanical complexity, connectivity and hydraulic isolation.
Spring 2004
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