Print this pageRanking of Possible Processes Leading to Heavy Oil Zones by Basin and Petroleum Systems Modeling — A Kuwait Case Study
Biodegradation, water washing, oil mixing, degassing along faults and gravity segregation are possible reasons for alteration processes in reservoirs that can lead to heavy oil occurrence. Detailed knowledge of the charge history of the reservoir is one critical element in order to understand these processes. The description of the charge history and the natural processes that lead to a heavy oil occurrence in the reservoir can be assessed by Basin and Petroleum Systems Modeling over geologic timescales using high resolution multi phase kinetic reactions for the kinetic modeling of source rock maturity and the produced crude oils, in combination with PVT modeling of the reservoir. Source rock tracking allows the description of the charge history of each accumulation in high detail.
Migration induced heavy oil occurrence can be caused by mixing of different oil phases in the reservoir and the different migration timing of produced components in the source rocks with maturation of this source rock.
In basin and petroleum systems modeling, the resolution of the model is in most cases too coarse to be able to describe the distribution of single components of oils in reservoir scales properly. In large, regional scale petroleum systems on the other hand, the kitchen areas of the source rocks can be sometimes tens to hundreds of km away from the trap structures where the accumulations can be found. To solve this dilemma a new method is applied to an oilfield in Kuwait by combining a regional scale petroleum systems model with a local high-resolution model of the field.
The migration from the kitchen areas to the reservoirs is modeled using the regional model. In a second step, the simulation results for temperature, pressure and fluid flow from the regional model are taken into consideration by the local model and migration from the regional model is applied to the high-resolution geometries of that local Model. The PVT boundary conditions of the regional model are taken, to constrain the local model.
In a case study of the application of this method to an oilfield in Kuwait the different possible processes leading to heavy oil in the reservoir have been investigated and ranked in their importance. The results of this study will be used to further improvement of the reservoir model of the field and a refined resource assessment.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil