Ultradeepwater Drilling Campaign, GOM Perdido Fold Belt | SLB

Drilling Evolution of the Ultra Deepwater Drilling Campaign in Mexico, Perdido Fold Belt

Published: 03/23/2014

Schlumberger Oilfield Services

The Mexican National Oil Company (NOC), PEMEX, increased its ultra-deep-water exploration investment in the North Tamaulipas region of the Gulf of Mexico after four major oil deposits were discovered during 2012 and 2013. The new ultra-deep-water Perdido fold belt exploration region has a high potential for commercial production. The hydrocarbon reserves from the Perdido region were found in the Tertiary geological system that includes the Middle Oligocene Frio sandstones, Lower Eocene sandstones, and the Lower Paleocene sandstones. This region has challenged the ultra-deep-water semisubmersible rigs to work at their operational technical limits. The technical challenges include ultra-deep-water depths (more than 1,500 m < 2,900 m); narrower drilling mud weight windows; shallow geohazards; subsalt drilling; deeper target depths (7,000 m to 8,000 m); high-pressure, high-temperature (HPHT) conditions; and uncalibrated pore pressure models derived from seismic velocities obtained from surface seismic. Accurate reservoir evaluation is challenged with known low resistivity pay and highly laminated reservoirs, complex geology that consists of high angle dips and faulting. Operating conditions are impacted by remote offshore operations with complex logistics.

The NOC has successfully drilled three wells in the Perdido area with oil reservoir discoveries: Supremus-1 and Trion-1 drilled in 2012, and Maximino-1 drilled in 2013. Currently, the operator is drilling one appraisal well and another exploration well in the Perdido area, applying the lessons learned to reduce nonproductive time (NPT) and improve drilling performance in every hole section. The cross-functional drilling group comprising of drilling engineers and Geologist and Geophysicist (G&G) members utilized the front-end- loading methodology to define stage gates and well-defined milestones within the project's lifecycle to ensure the important lessons learned were communicated and applied on subsequent wells.

The project’s economic priority to optimize investment and reduce costs requires a comprehensive approach to the design and operational requirements. The process starts with good planning and testing multiple design scenarios with specialized software that can help recreate possible operational conditions. The well design may include multiple contingencies that may increase the number of casing strings, thus the importance of performing efficient simultaneous formation evaluation, drilling, and hole enlargement activities. Drilling and undereaming operations must consider the real- time data acquisition that requires complex drilling assembly designs that include logging-while-drilling (LWD) and measurement-while-drilling (MWD) tools. Hole size and wellbore quality are considerations for the wireline evaluation program in acquiring the data needed for reservoir characterization. Acquiring wireline pressure and fluid samples is more difficult in shallower geological targets where a hole size of 12 1/4 in is considered the optimum size for achieving best results.

Mexico, North America, Offshore
Victor G. Vallejo, Aciel Olivares, and Octavio Saavedra, Pemex; Juan R. Lopez and Manuel E. Torres, Schlumberger
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