The Who Dat Development: Evolution of a Project from Lease Sale to First Production

Abstract

This paper provides an overview of the Who Dat development. The Who Dat fieldis located in the Mississippi Canyon protraction area of the Gulf of Mexico inblocks 503, 504 and 547 and is being developed using the OPTI-EXsemisubmersible floating production system (FPS) which has a capacity of 60MBOPD and 150 MMCFD. The Who Dat discovery is primarily oil and consists of tenstacked amplitude-supported reservoirs in a salt withdrawal mini-basin. Threewells have been drilled to date penetrating over 700' of net pay in ninedistinct reservoirs ranging in depth from 12,000' to 17,000' TVD. The fieldwill be developed with twelve subsea wells (i.e. wet trees) flowing to threesubsea manifolds and subsequently to the FPS via two infield flowloops usingflexible risers. The project includes a 10" gas export line and 14" oil exportline also using flexible risers. The paper covers the exploration phase including evaluating the prospect priorto the lease sale and adjusting the delineation plan based on the discoverywell. The paper also covers the development concept selection including theevolution of the project from a long subsea tieback to a new FPS, thechallenges of utilizing an FPS that was built on a speculative basis(modifications required, regulatory approval), and contracting strategy(negotiation of an installment purchase and managing uncertainty in apost-Macondo environment). This development represents a number of firsts: first time that a privatecompany will own an FPS, first time the OPTI-EX semisubmersible FPS will beused, first time an FPS has been approved for installation post-Macondo, firsttime an FPS has been built on speculation, and first time a field has gone fromconcept selection to installation of a new FPS in less than a year. Theproject's accelerated schedule created challenges since numerous items were oncritical path, including items that are typically nowhere near criticalpath. New Seismic Shows Previous Wells were Drilled in Poor Locations. There were a number of amplitudes (bright spots on the seismic data) that werepreviously identified in the Who Dat Area. The objective section, LowerPliocene though Upper Miocene had been drilled in offset blocks MC 460/502/546. The wells were drilled in these blocks from 1985–1998 and found thin and/orpoor quality hydrocarbon bearing sands. Operators presumably assumed that theresults of these wells meant that all of the amplitudes in the area were thinand uneconomic which is the likely reason British Borneo allowed blockMississippi Canyon Block 503 (MC 503) to expire without drilling a well. Withthe release of the TGS MC Revival PSTM 3 D data set in the spring of 2004 overthis area, the poor placement of these wells and the thin pay results werebetter explained. This did not alleviate the risk of finding thin pays in otherwells but LLOG felt it could explain the poor result.