An Integrated Workflow for Petroleum Systems Modeling and Prospect Generation
Authors: Mezghani Mokhles , AbuAli Mahdi , Alqattan Hussain , Schmidt Rainer 
Published: November 2018

Abstract

Objectives/Scope
The challenge of optimizing exploration activities using numerical modeling is in having accurate model predictions with acceptable uncertainty tolerance for use in the decision making process. Unfortunately, the prediction results of typical numerical models bear major uncertainties, making any decision-making based on these models risky and greatly increasing exploration costs. The objective of this abstract is to develop an integrated workflow accounting for all geological processes from source to trap.

Methods, Procedures, Process
Aside from tectonic and structural influences, two major processes are responsible for hydrocarbon accumulation: deposition of sediments and fluid migration. Combining these two processes in a single modeling workflow is a powerful approach for accurate quantitative modeling of petroleum systems (forward modeling). This workflow can be used to predict new resources with some range of uncertainties. These uncertainties can be minimized by calibrating the integrated workflow with the well and seismic data (inverse modeling). Therefore, an optimization loop is added to the workflow to automatically calibrate the forward model to the available data: core description, horizons, borehole temperature, pressure, vitrinite reflectance, fluid analysis, known reservoir volume.

Results, Observations, Conclusions
This workflow was implemented for eastern Saudi Arabia (upper Jurassic). First of all, a forward depositional model was built to model the 3D facies distribution within the area of interest. To reduce the uncertainties associated with the 3D facies distribution, the forward depositional model was calibrated with well facies (facies from core description and predicted electro-facies using wireline logs). The 3D facies distribution derived from the calibrated depositional model was used to model and simulate the petroleum systems for the same area of interest (forward model). Data from the wells are used to calibrate the petroleum system model to improve its prediction capabilities. The combined model was used to quantitatively assess the four elements of the petroleum system: source rock, closure, seal, and reservoir rock. Reasonable agreement was obtained between the workflow prediction and the observed hydrocarbon accumulation in eastern Saudi Arabia. This agreement has provided enough confidence to the asset team to use the combined calibrated model in generating new prospects in the area of interest.

Novel/Additive Information
Source rock, closure, seal, and reservoir rock are key elements of identifying a petroleum system. Conventionally, each of these elements is evaluated independently from the others. Our quantitative workflow for prospect generation, using numerical modeling and simulation, is assessing prospect integrity by considering the four elements simultaneously. Moreover, to reduce the uncertainties associated with the prospect generation and prediction, this workflow is calibrated with the historical data (well, seismic, etc.) collected from the nearby area.