Onyeagoro, U.O.1, S. J. Naruk1
(1) Shell International Exploration and Production, Houston, TX
ABSTRACT: The Impact of Dynamic Behavior of Fault Zone to Field's Production and Development Strategies
In greenfield or new-field wildcat exploration for fault traps, it is of course critical to be able to predict the static, or geologic-time, seal capacity of the prospect-bounding faults. In contrast, in brown-field or near-field exploration, and in field development, it is critical to be able to predict dynamic fault-seal capacities, i.e., whether or not existing production from one fault block has “broken-down” a fault, caused cross-fault flow, and depleted a nearby fault block. This is especially important in complexly faulted Deep Water developments, where individual wells cost on the order of 50-100 million USD.
Even in relatively less costly but complexly faulted fields like those in the onshore settings of the Niger Delta, dynamic fault seal prediction is critical to well optimization. In particular, estimation of cross-fault flow and fault transmissibility in these influences well counts, well placements, and ultimate recoveries of individual wells and the entire field.
For faulted reservoirs, significant cross-fault production of hydrocarbons appears to be the exception rather than the rule. The real challenge is to find those faults that will allow adequate cross-fault oil production and thereby save the cost of additional wells.
The dynamic fault seal prediction techniques have been applied in the Niger delta, Gulf of Mexico and North Sea to drill high angle wells, design pressure interference tests and obtain better history matches and forecast scenarios in reservoir simulations. These applied results have yielded a producing 20,000bbls/day well, proposed well trajectory that will drain about 80MMSTB connected volume of oil and drilling of an additional well to recover by-passed reserves trapped under a fault compartment.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.