Integrated Reservoir Characterization for Efficient Exploitation of J Sandstone Reservoir,

Wattenberg Field, Denver Basin

By

Guonong Hu and Jeffrey C. Simmons

Kerr-McGee Rocky Mountain Corporation, Denver, CO

The J Sandstone is one of the most important hydrocarbon reservoirs in the Wattenberg Field. Since 1998, field operators have been implementing an active infill-drilling program, which is breathing new life to a 30-year old field, with very attractive economic results. Some background information about the infill-drilling program is presented. It is recognized that in order to have a successful infill-drilling program, two crucial challenges must be met: 1) delineate areas within the reservoir region that have favorable geological conditions; and 2) understand the present reservoir drainage status as well as the remaining reserve and pressure distributions.

Accordingly, we will discuss several important geological factors controlling the reservoir productivity trends, such as reservoir rock distribution and petrophysical/diagenetic characteristics. The discussion is based on a very detailed geological study, which used data from 3,600 J Sandstone penetrations in the Wattenberg Field.

We will also present the concept and application of an infill-drilling simulator (MBCONIX). It was designed to provide a platform to conduct integrated geological and engineering reservoir studies. The simulator combines an elliptoconic drainage model with engineering and geostatistical analysis techniques. It can be used to evaluate the reservoir drainage status at different time frames, adjust infill well reserves for offset drainage effects, make pre-drilling predictions of reserves, predict pressures for any potential infill location and run what-if scenarios. When coupled with properly designed databases, the simulator can be used to select and rank infill locations, perform pre-drilling economic analysis and optimize drilling sequences. It also helps to streamline and simplify the tasks in the planning, management and optimization of a large, multi-year infill-drilling program, providing accuracy, consistency, vigor and completeness. The simulator is written as a single efficient computer program, which greatly simplifies its use.

AAPG Search and Discovery Article #90004©2002 AAPG Rocky Mountain Section, Laramie, Wyoming