Auger TLP Well Systems
Authors: Petersen W.H. , Patterson R.W. , Smith J.D. , Denisen E.B. , Allen D.W. , Ekvall A.G. , Phifer E.H. , Li You Sun 
Published: October 2008

The Auger TLP well system permits use of proven deep water drilling methods and platform-like completion techniques. Key features enabling these operational advantages are a lateral mooring system, a spread well pattern, an open well bay with special well handling equipment and production risers having surface well heads and trees. Significant advances in the understanding of Gulf Of Mexico eddy currents, riser interference and vortex-induced vibrations were made in support of the Auger TLP project.

INTRODUCTION

The Auger TLP well system is designed to drill, complete, produce and maintain up to 32 wells in a record 2860 feet of water (Ref. 1, 2). The well system is based on a unique combination of deep water dri11ing methods and completions similar to conventional, bottom-supported platforms. Auger wells are deep, geopressured, and configured to produce oi1 and gas using gravel packed completions. Auger's well system features include:A spread well pattern for running and retrieving components to the seafloor in the open center of the well pattern without guidelines.Subsea wellheads installed in an oval pattern without use of a unitized template.A rig fixed at the TLP center and a 1ateral mooring system for positioning the rig over the subsea wellheads.A rectangular, open wellbay having special well handling equipment.A guidelineless, deep water dri11ing system employing a subsea diverter and a subsea BOP.Oual-casing production risers with surface wel1heads trees.A surface BOP for well completions and workovers.Rocker- arm-type production riser tensioners having nitrogen-filled, elastomeric compression elements.

Significant efforts were made to design production and drilling risers suitable for operational and environmental requirements. Riser interference, vortex-induced vibration tubular interaction, and connections were studied and validated by 1aboratory experiments. A new threaded connector for the 9 5/8-inch production riser was developed. All well system requirements have been met.

SYSTEM DESCRIPTION

General

Design of Auger's well system was based on the fol1owing principal requirements:Provisions for 32 wells in 2860 feet of water.Pre-drilling from a mobile rig.Drilling, completion, and maintenance from the TLP.Deep (19,000 ft. +- TVD), mildly geopressured reservoirs.Deep water, floating dri 11ing methods using subsea BOPS and low pressure drill ing riser.Dual-casing production risers (9 5/8-inch × 7-inch) having surface trees and surface completion/workover BOPS.Gravel packed completions.Low concentrations of C02 and possible future H2S.Design shut-in tubing pressure of 7500 psi.30 year design 1ife in Gulf of Mexico environment.Ccmpliance with applicable industry regulations and guidelines.

Seafloor Well Equipment

A dispersed, seafloor wellhead pattern, in conjunction with the rectangular, open-type, topside wellbay, was selected to allow running and retrieving components to the seafloor without guidelines - (Figures 1 and 2). Wellheads are installed in an oval pattern (98 feet × 208 feet) on 16-feet centers without the use of a traditional template.