Parameterization of Mudrock Properties for Pre-drill Pressure Prediction via Burial History Models

Michael Cheng*, Jennifer Wolters, Raleigh Blumstein, Robin Pilcher, Andy Pepper, and Niall McCormack
Hess Corporation, One Allen Center, 500 Dallas Street, Houston, Texas, USA
* Corresponding author: [email protected]

Importance of pre-drill pressure prediction cannot be overemphasized in the context of safety, environment, and drilling costs. High overpressures are often encountered during exploration drilling in mudrock-dominated sedimentary basins such as the Gulf of Mexico, offshore Trinidad, and Caspian Sea. Burial history modeling is a technology routinely applied for pre-drill pressure prediction. This technology applies numerical codes/softwares to simulate loading of sediments, compaction, and draining of pore water, results of such simulation include pressure and effective stress for present day and geological past. Selected software for pressure prediction may be a commercial vendor product (e.g., Temis, PetroMod) or a company-proprietary code, nevertheless Darcy’s Law is the same underpinning for these numerical codes. These softwares, even though with abundant validation and stability testing, still may yield variant output. Equally variant, if not more so, is the model building and calibration procedures among petroleum systems analysts. In our collective opinion accuracy and robustness of pre-drill pressure prediction models, to a large extent, depend on selecting geologically-sensible parameters for mudrocks, including compaction curves, poro-perm relationship, and permeability anisotropy ratio, among others. Such parameters are generally not well constrained because reliable direct measurements are currently not yet available for mudrocks.

We present our technique for parameterizing burial history models, including mudrock properties and their evolution (family of compaction curves and poro-perm relationships), model calibration, overall workflow, and pre-drill/post-drill comparison. This paper is intended to stimulate discussion in hope of an improved procedure for pre-drill pressure prediction via burial history models.

 

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands

 

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands