This paper will illustrate the collaborative approach an international oilfield services company and Gulf of Mexico operator used for the planning and successful execution of a 9-7/8-in. x 14-in. Drilling with Liner (DwL) operation to isolate a 6.5 ppg depleted sand interval and mitigate expected losses in a deep water block of Mississippi Canyon. Conventional methods would have most likely have required an 11-3/4-in. or 11-7/8-in. contingency liner for the operator to meet their well construction objectives. Early collaboration between the service company and operator identified DwL technology as the core technology to meet the operator's well construction objectives. The DwL process allows a hazard interval to be isolated in a single trip resulting in less risk and exposure compared to the use of conventional drilling methods. Since DwL technology encompasses a multitude of engineering disciplines, these were integrated into the drilling plan in a seamless manner, ensuring the DwL objectives would be met. To accomplish this, the service company formed a dedicated well engineering team which collaborated with the operator early on in their well planning process.
The engineering disciplines with associated modeling during the DwL planning phase provided technical assurance the 9-7/8″ liner string could be drilled to a satisfactory setting depth while also providing a high-integrity wellbore to the operator over the entire life of the well. These disciplines included:
Torque, drag and hydraulics modeling of the liner running and drilling operation,
Connection cyclic fatigue analysis,
BHA and directional tendency modeling
Cementation and centralization
Formation drillability analysis
Plastering effect evaluation
During the planning phase, regular operator-service company communications along with project scheduling software gave the operator assurance that agreed upon deliverables would be completed in the allotted time frame with the intended well objectives met.
The 9-7/8-in. x 14-in. liner successfully drilled through the depleted sand reaching a competent setting point, eliminating a potential contingency liner. This paper will present the DwL planning process, associated risk assessment modeling to ensure that safety, environmental and DwL objectives were met, and the DwL operation with its successful outcome