An Overview of the Baldpate Project
Authors: Simon John V. , Edel James C. , Melancon Charles 
Published: October 2008

The Baldpate project, completed in 1998 in Garden Banks block 260 in the Gulf of Mexico by Amerada Hess Corporation (AHC) as operator, and Oryx Energy Company as 50% joint-interest owner, included the first use of a freestanding, non-guyed compliant tower. Initial production was in September, 1998. This paper discusses the overall project: the tower, the production facility, the wells and the pipelines. Some focus is given to the selection of a compliant tower over other options for basing of the production facility, and the selection of an articulated tower over several other configurations.

Introduction

The Baldpate project (named after a breed of duck whose name was lent to the original exploration prospect) comprised production facilities for 60,000 BOPD and 200 MMSCFD; two export pipelines (16" oil and 12" gas) connecting to the platform via steel catenary risers; 7 pre-drilled wells; provisions for future platform-supported water-injection wells and equipment, and for tie-ins from remote subsea locations; and a 19-slot drilling/production platform, set over a 9-slot drilling template. This platform, the first free-standing, nonguyed compliant tower, is in 1,648 ft of water and measures 1,900 ft from its flare tip to the seafloor. It also, briefly (i.e., before the Texaco Petronius tower was installed later in the same year) held a record as the tallest free-standing structure in the world, eclipsing the CN Tower in Toronto; the only taller structure of any sort was a guyed radio antenna in North Dakota. The platform was installed in the spring of 1998, and first oil was achieved in September, 1998, at the conclusion of completion operations on the first well.

This paper discusses the background of exploration and development; geology and reservoir characteristics; and selection of the final development concept from among the other alternatives of a floating production system, a spar platform, and a tension-leg platform. In addition, the paper discusses the topsides, pipelines and wells, and overall project schedule and costs. Companion papers offer more in-depth treatments of several other topics: platform design; responsebased metocean criteria; fatigue and wear; platform fabrication; platform installation; and design and installation of the catenary risers.

Project Background

Garden Banks blocks 215 S/2, 216, 259 and 260 were acquired in lease sales in 1984, 1987 and 1989. The Baldpate Unit, comprising all but block 216, was approved by the Minerals Management Service in February, 1991. Block 216 was added to the unit in February, 1994.

The discovery well was drilled by the Diamond Offshore semisubmersible "Ocean Rover" in late 1991, and showed 180 ft of net pay. After several sidetracks to delineate the reservoir, and comprehensive seafloor survey work to identify a suitable development site, the first production well, the GB 260 #3, was drilled and temporarily abandoned at the selected site. A 9-slot template was later fixed to the low-pressure housing of this well, and used to guide the placement of six more development wells drilled from the Ocean Rover and temporarily abandoned before the platform was installed.

The development project, consisting of the construction work and remaining development drilling and completions, was sanctioned in November, 1995 with a budget of $320 million.

Reservoir

The primary Baldpate pay sands, the "Big Sand" and the "Twin Sand", are Pliocene-aged basin-floor fans truncated along the southwest flank of a shallow tabular salt feature (Fig. 1). These two main reservoirs are sheet-type sands that exhibit excellent lateral continuity and consistency, with average porosity of 29% and per