Technical Paper: BC-10: Meeting Drilling Challenges in Shallow Extended Reach Wells

Society: IBP
Paper Number: IBP3092
Presentation Date: 2010


Shell Brazil is developing a structurally complex reservoir in a deepwater, shallow overburden setting. Based on data from one vertical exploration and one appraisal well, the development plan called for completion of six 600-m to 1,200-m long horizontal producers.

The shallow nature of the field (900 m to 1,100 m TVD below mudline) resulted in the need to start the buildup section near mud line. Building the 17½-in hole to 40 degrees inclination in the initial 550 m true vertical depth subsea was found to be very challenging in soft Pliocene and Miocene sediments using the original BHA design.

As problems were identified, Shell well engineers and subsurface teams together with the Schlumberger drilling team worked to optimize drilling parameters through the integration of drilling and subsurface data. Understanding the drilling behavior of specific formations and the lithology at various depths helped in the redesign of BHAs and well paths, refinement of the steering program, and updating of the LWD requirements.

3D and 2D displays of seismic, wellbore lithology, and drilling data such as steering ratio, buils rates, and ROP were used to better understand the relationship between geologic formations, lithology, and drilling behavior. Integration of drilling, directional drilling, and subsurface data was critical in overcoming the challenges and led to significantly improved drilling performance and well placement in some of the most difficult deepwater extended-reach wells ever drilled.

The world’s first point-the-bit RSS BHA from Schlumberger with 17½-in under-reamer was used to directionally drill to the limits of shallow extended reach drilling experience for deep water. Modeling software to project and visualize drilling data across the field was required to predict drilling environment and hazards and be able to construct the correct wellbore is complex lithology avoiding loss of directional control and mud losses while maximizing net to gross..

Technical Paper presented at 15th Rio Oil & Gas Conference, held on Sep 13 -16th 2010 at Rio Centro/RJ.

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