Exploration drilling activities are not endeavors that afford optimization given the variability of the drilling environment and inherent uncertainty of the lateral discontinuous geology. The ongoing exploration drilling program comprising several wells and various wellsites in the shallow waters of the Red Sea is providing an opportunity to progressively refine exploration drilling practices, and extract incremental efficiencies while maintaining a zero saftey incident record.
The Saudi Aramco shallow water exploration drilling program is targeting a transition zone corridor approximately 10-30 km wide in shallow to moderately deepwater straddling the coastline at the northwestern end of the Red Sea. Given the proximity of the Burqan and Midyan fields, geological and stratigraphic analyses are developed using analogues from extensively studied geophysical and geomechanical models.
Initial well designs developed from the basis of design anticipated extensive salt sections and moderately divergent geopressure beginning in the rubble zone and extending beyond the Kial formation. After drilling two successful exploration wells, learnings from solutions developed to address drilling challenges are presented.
Optimization of the casing design afforded by the use of large bore logging while drilling (LWD) tools is complemented by a bottom-hole assembly (BHA) reconfiguration based on results of a BHA dynamics study. The high temperature profile of the wells drilled also presented another dimension to the challenge as well the opportunity to test emerging high pressure, high temperature (HPHT) logging technology. The pore-pressure fracture gradient (PPFG) profile emulating a post-salt abnormally geopressured trend and strike-slip stress regime initially elicited the use of seismic while drilling technology to resolve poor imaging difficulties below the salt but subsequently discontinued to determine the best lookahead strategy and job design.
Ensuring environmental stewardship required careful planning for the disposal of waste from drilling cuttings. For the frontier area in the Saudi Arabian Red Sea, the extensive environmental impact assessment and measures to ensure compliance with national and corporate environmental policy is also presented.
