An Innovative Approach to Development Drilling in Deepwater Gulf of Mexico

Abstract

Anadarko Petroleum's Marco Polo development is located in approximately 4,300 ft. of water in Green Canyon Block 608, in the central Gulf of Mexico (GOM). The discovery and appraisal wells were drilled in 2000, and the field will ultimately be produced using a tension leg platform (TLP). The development drilling, which will be complete by 1st Quarter 2003, uses several innovative approaches to maximize project value. Some of the approaches challenge current industry trends and will be highlighted in this paper. Introduction Over the past decade, multiple fields in deepwater GOM have been developed and the region remains one of the frontier exploration areas of the world. The challenge of the Marco Polo development is the same as with most projects - to deliver maximum value. What makes this project unique is the approach. The first step was to evaluate the major components to determine the most appropriate use of current technology. Those selected technologies that significantly challenge current industry trends include: Rig Selection. The rig selected to drill the development wells is an Express-Class, dynamically positioned fifth generation semi-submersible with enhanced pipe handling capabilities. Drilling Fluid System. A newly developed water-based mud (WBM) was used in lieu of the synthetic-based drilling fluids (SBMs) traditionally used in the GOM. Cement Design. To address shallow water flow concerns, a non-foamed slurry was used on the conductor casings instead of foamed cement-the predominate slurry for cementing conductor casing in shallow water flow areas in the GOM. Additionally, a flexible slurry was used on the production casing to mitigate annular pressure buildup (APB). Both of these slurries are new developments in technology. Casing and Wellhead Design. The casing design was optimized from the exploration wells and drew on recently published casing failures in deepwater GOM1. Subsea wellheads were used and will be tied back to the surface once the TLP is installed. To meet the design criteria, the wellheads included a "thick wall extension" below the 18 3/4-in. high-pressure wellhead housing (HPWHH). The 36-in. low-pressure wellhead housing (LPWHH) and casing above the mudline was also externally insulated for flow assurance reasons. Rig Selection As with all drilling projects, rig selection plays an important role in success - particularly with batch set operations. Key issues related to rig selection for the Marco Polo project included:The ability to work in high current environments. Immediately prior to beginning the drilling program, a fourth generation, moored semi-submersible had drilled a well in an offset block where loop currents were present. As a result of these high loop currents, the drilling operation was suspended a total of 21 days.Enhanced pipe handling, which could add significant value during batch set operations.Variable deck loadLiquid mud storageBulk storage (cement and mud)Hydraulics Once qualifications were set, the rig list was narrowed down to two rigs;a fourth generation moored semi-submersible that had been used to drill the discovery and delineation wells and an immediate offset; anda fifth generation dynamically positioned (DP) semi-submersible with enhanced pipe handling capabilities. Because a batch set operation was planned, the fifth generation rig's increased variable deck load, additional bulk storage, and enhanced pipe handling capabilities delivered improved performance over the fourth generation rig. These features, combined with DP capabilities, established the fifth generation rig as the optimal choice.

Development and Performance Evaluation of a Deep Water Synthetic Based Drilling Fluid System

“…The oil field has achieved great success [5] [6] huge benefits [8]. However, the rheology of the second-generation synthetic-based drilling fluid is greatly affected by temperature [9]. The viscosity of the drilling fluid is too high at low temperatures, and the viscosity of the drilling fluid is too low at high temperatures, especially the dynamic shear force is too low to carry the solid phase in the drilling fluid effectively [10].…”

Methods of setting depth range with credibility of conductor for deepwater drilling based on probability statistics

“…Affected by the drilling vessel drifting and sea current beating and other issues, the riser would threaten the stability of subsea wellhead mechanics [4][5][6][7]. Recent years scholars have conducted relational studies such as riser stress state, the stability of subsea wellheads, the bearing capacity of casing string below the mud line, the setting depth of conductor and so on, they have drawn some valuable conclusions [8][9][10].…”