Bridging the Gap Between Thermal Modeling of Sedimentary Basins and Potential Fields Modeling: Using Geophysics to constrain Hydrocarbon Charge Models In Data-Poor Frontier Areas
Authors: Kennan Lorcan , Kuznetsova Natalya , Spaak Michael , Hafkenscheid Edith , Meuric Olivier , Podlaha Olaf , Biegert Ed 
Published: March 2015

We integrate subsidence, thermal, and potential fields modelling in a single, unified workflow which reduces the propagation of uncertainty when building geological models of data-poor frontier areas such as deepwater continental passive margins. Subsidence analysis is combined with a model for the relationship between mantle melting and lithosphere stretching and resulting isostatic equilibrium to estimate crust thickness and type and the temperature and density of the crust and underlying mantle in the past and at present. The results can be compared to observations, including potential fields such as gravity in addition to well data if this is available. The integration of potential fields and thermal modelling is particularly important in frontier areas where well data is sparse to absent and conventional calibration data (T, VR) is not available to basin modellers. Our methods have been applied to a number of circum-Atlantic margins, allowing us to build basin scale play concepts and hydrocarbon maturation and charge models with greater confidence and guide exploration decision making.

Introduction

Basin subsidence on passive continental margins is a function of sediment-loading and of thermal subsidence (driven by crust and mantle density changes due to thinning and subsequent cooling). The stratigraphy of passive margins acts as a recorder of continental breakup processes. Integrated workflows and tools which model the breakup process can help reduce exploration risk associated with basin scale petroleum systems evolution and help identify appropriate global analogues.

Integrated basin analysis workflow

A wide-ranging collaboration between teams involved in research, software development and deployment, and exploration in both frontier and mature areas has enabled us to develop new basin analysis and modelling tools which integrate with, and leverage the strengths of, both proprietary software and the work of external research partners.

The exploration context

Integrated basin analysis is a vital component of basin to prospect screening of exploration acreage and reconnaissance hydrocarbon charge modelling on data-poor deepwater passive margins. It can contribute significantly to the identification and reduction of geological and stratigraphic risks prior to drilling and provides the framework for analysis of relevant well data, in both discoveries and dry holes, adjacent to the areas being screened.

Building and constraining models for basin evolution

We combine regional geological observations such as constraints from plate tectonic models, backstripping of the basin fill, analysis of physically plausible tectonic subsidence mechanisms, stratigraphic forward modelling and petroleum systems (i.e. hydrocarbon charge) analysis. Tighter integration of a number of workflows yields internally consistent, repeatable and reliable results which can be tested with a wide range of data. Well and outcrop data can be used to calibrate basin models, but in areas where limited (or no) data is available we can also validate models with gravity and magnetic data.