Subsurface Review of the Who Dat Field
Authors: Zimmermann Eric , Cole Jay , Doughtie John 
Published: April 2012

The MC 503 Prospect was leased in 2005, and subsequently drilled in 2007. Afterthe initial discovery well was drilled, the block MC 547 was leased in 2008. Appraisal and delineation wells were drilled in 2010 to confirm the discoveryand decide the most appropriate means of developing the field. The field isgeologically interpreted as a prograding turbidite system. The deeper sands(Upper Miocene) are interpreted to be basin floor fans which are overlain byprogressively more channelized facies (Lower Pliocene). Geophysically, themajority of the events are Class III amplitude anomalies, with the exception ofthe oldest and deepest horizon which is Class II. After cross plotting log toseismic parameters, a strong correlation was found between net pay andamplitude strength. Because the pay zones in the field are sub-tuning, thiscorrelation was critical in resource mapping and determining the originalreserves in the field.

Introduction

LLOG Exploration was founded in 1977 and was built on developing prospects inS. Louisiana onshore. As the company grew over the years it started moving intoOCS shallow waters and in time the company made a decision to move into thedeepwater. To accomplish these goals, the company acquired a seismic inventoryallowing it to explore and drill in the deepwater.

MC 503 came to review as a prospect in the 2005 Central Lease Sale 194. Theprospect had 3 stacked objectives with amplitude and AVO support and gooddowndip fit to structure. A single well could test 3 objectives - the4000/4200/4800 horizons. All 3 objectives were Class III AVO anomalies. Thetrap for these potential reservoirs was located on the south side of a saltfeature and exhibited both a structural and stratigraphic component withevidence of aquifer support. Due to the lack of well control in the area, aswell as amplitude strength exhibited by each objective, the most likelyhydrocarbon type was projected to be gas.

The Mississippi Canyon 503 lease was available for the first time since 1994when it was leased by Shell and later farmed out to British Borneo. Theobjective section, which is lower Pliocene to Upper Miocene, had beenencountered in the offset blocks which are MC 460/502/546. Wells were drilledin these blocks from 1985–1998, and found thin hydrocarbon bearing sands. Additional review of the seismic data helped explain the placement of thesewells and the thin pay results. This did not alleviate the risk of finding thinpays in other wells but it could explain the poor results. Based on all LLOG'spre lease sale work the decision was made to bid this block. LLOG submitted a$6.7 MM bid for this block, the highest among seven others bids which includeda total of 11 companies.

LLOG drilled the first well on MC 503 in November, 2007. The well was drilledand the results exceeded pre-drill reserves estimates, from higher net to grosswhich was as high as 90% plus the condensate yields were greater than expectedwith 45-90 bbls/mmcf. The 4000 sand had 72' net pay with a net to gross of 90%and a condensate yield of 40 bbls/mmcf. The 4200 sand also had a high net togross plus it is a gas reservoir with an oil rim.