Medusa Project: Integrated Planning for Successful Deepwater Gulf of Mexico Completions

Abstract

The following will outline the Medusa Field development and completion design process highlighting an integrated approach between engineering disciplines and service providers to exploit the enormous amount of exploratory well data. The Medusa development, located in Mississippi Canyon blocks 538 and 582 offshore Louisiana, is a truss SPAR allowing for both dry tree production and multiple subsea tiebacks.A field overview from a geological and reservoir perspective, along with the drilling and field development considerations, will be summarized. The initial phase of the Medusa truss SPAR development includes ten compaction-tolerant FracPac completions in six dry-tree wellbores.Phase II wells included the drilling of two subsea tiebacks.One was drilled and deemed uneconomic while the second, Medusa North, was completed and tied back in early 2005. The paper will show how the information gathered during the drilling phase was applied to the completion design to ensure long-lasting, reliable and profitable wells. Introduction Design of deepwater completions requires a vast amount of planning and communication between all involved engineering disciplines. Bridging the gap between petrophysical, drilling, completions, and operations is imperative to obtaining project profitability through efficient, long-term and robust completions. Mechanical integrity is crucial to any completion design.Deepwater and subsea completions command very high production rates and can require fewer wellbores to develop a field.Add to this the high cost of well intervention and efficient, dependable wells with stacked pay horizons become the primary driver to economic deepwater Gulf of Mexico field development. The quality of a deepwater completion relies heavily on the proper use of reservoir data gathered during the drilling phase.Since it has a direct bearing on the efficiency of the completions, accurate analysis and use of this reservoir data must occur subsequent to the drilling phase.In particular, fluid samples, core samples, and logging data are all imperative. Field Overview The Medusa development, under Mississippi Canyon blocks 538/582 in the Gulf of Mexico, is about 100 miles south of New Orleans, Louisiana in about 2,200-ft of water (Fig. 1). The Medusa prospect originated from the drilling of two exploratory wells from a semi-submersible rig beginning in August 1999.These wells were sidetracked to further delineate the field and gather valuable core, fluid and logging data.Upon drilling of the discovery wells, an evaluation period followed in which economic decisions were made. Once field development was sanctioned, a development drilling program was initiated.Simultaneously, the design and fabrication of the truss SPAR production facility began. Medusa Field Development Timeline 08/99 - Spud Discovery Well 10/99 - Discovery Announced 05/00 - Delineation Drilling Complete 03/01 - Contract Awarded for Floating Production System 07/01 - Development Drilling Begins 03/02 - Development Drilling Complete 02/03 - Hull Installation 05/03 - Topsides Installation 07/03 - Topsides Commissioned 09/03 - Initial Completion 11/03 - First Oil The time from the end of the drilling phase to the commissioning of the production facility was used to analyze all available reservoir data and explore various completion techniques.From this analysis, mechanically sound, high-rate completions were designed and a reservoir depletion plan was developed to efficiently produce the hydrocarbon reserves from the multiple sands in the field.