Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Qatar Integrated Charge Evaluation: Sensitivity and Uncertainty Analysis Study Using Experimental Design
(1) Fluids and Basins, Shell International Exploration and Production B.V., The Hague, Netherlands.
As part of a regional review of the Palaeozoic petroleum system of Qatar, an integrated charge study was undertaken to investigate the distribution of hydrocarbons in Palaeozoic reservoirs. The charge study, uses geochemical analyses and 3D basin modelling to detail the structural development and trap filling history of Khuff reservoirs as well as determining generation and expulsion behaviour from the Silurian aged Qusaiba Formation source rock.
The key results of the study are; (i) Qusaiba specific source rock kinetics combined with realistic thickness and richness estimates can explain the reported gas volumes, (ii) Reservoir fluid 
phase
is governed by the recent PVT history, and even slight changes in pressure or temperature can result in phase change within the reservoir.
In order to test the sensitivity of the results to uncertainty in the input parameters, experimental design was employed. In the initial screening phase, input variables were varied to discover which of these had most influence on the volumes, GOR, CGR and API of the discovered fluids. The results show that while the depth and thickness of the source rock had the most influence on absolute volumes, the fluid composition and phase was most affected by depth, hydrogen index and expulsion kinetics of the source rock. In addition, the magnitude of uplifts associated with Tertiary unconformities had a significant effect on the phase
of reservoir fluids. The uncertainty ranges in the output resulting from uncertainties in the inputs are currently being investigated.