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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.

This paper presents a novel torque and drag analysis approach and demonstrates its robustness when used with a versatile computer program. Torque and Drag analysis remains an important evaluation process for assessing drilling feasibility of directional wells, minimizing the occurrence of catastrophic drill string failures and avoiding premature termination of the drilling operation before reaching planned target depth. From a draft well plan, the drilling engineering analysis is initiated with the development of a representative analytical model using selected entries in a Torque and Drag computer program. Several parameters and instances of evaluation are needed to capture the physical behavior of modeled systems and to produce technically sound results. The availability of computational tools have not necessarily improved the drilling engineering process or enhance the quality of recommendations without a methodical approach and application of results. To minimize the iterative steps required to reach an interpretable result, the analytical process as presented in this paper is accelerated with a directed starch and a convergence to the determinant drilling variables. The novel approach narrows - the design search domain and tests sensitivities of well-plan characteristics, simulates drilling conditions and applicable drillstring - to the dominant operating factors that determine the boundaries of application. A record extended reach well (MD/TVD ratio of 2.9) with a lateral displacement of approximately 6,000 ft. was drilled in the GOM using this approach to select tubulars and their position in the well with respect to well trajectory objectives, bottom-hole assembly (BHA) performance and target reach. P. 243

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Rank wild cat deepwater exploration wells present an escalated set of challenges beyond even those encountered in the most complex offshore well construction. The presence of salt diapirs and well documented stressed pre- and post-salt formation layers produce greater distortion and unpredictability to geopressure and temperature gradients. It is customary to approach these challenges with casing design configurations that afford deployment of contingency casing strings without compromise to mechanical strength, well integrity and reaching the bottom-hole depth objective with the right casing bore size for production testing. The use of expandable liners have become a panacea for extending hole sections — that may otherwise have truncated and narrowed the final depth — and terminating the hole size of deep reservoir targets respectively. Significant compromise in casing mechanical strength accompanies the application of expandable liners and their application must be carefully considered, alongside an array of qualified alternatives, especially above and across high pressured reservoir intervals. The Expandable Hanger and Packer Liner (EHPL) System offers the preservation of the maximum bore size for subsequent hole and casing size, while allowing deployment in the tightest annuli that otherwise will have prevented the pass through and space for a conventional hanger deployment to achieve liner design and effective hang-off capacity. In the account presented in this paper, the technical evaluation process, deployment planning and challenges, and successful application industry-wide of the first liner with an expandable hanger and packer system is enumerated.