The goal of this project was to develop generalized two- and three-dimensional coupled models for the direct simulation of near-wellbore mechanics. The models were applied to investigate and quantify a suite of industry-selected problems in the near-wellbore region that control the completion and production techniques employed by the industry.

Program
This project was funded through DOE's Natural Gas and Oil Technology Partnership Program. The program establishes alliances that combine the resources and experience of the Nation's petroleum industry with the capabilities of the National Laboratories to expedite research, development, and demonstration of advanced technologies for improved natural gas and oil recovery.

Sandia National Laboratories (SNL)
Albuquerque, NM

Several geomechanical processes in the petroleum industry, including sand production, hydraulic fracturing, and slurry injection, are dominated by the interaction of fluid and solid particles in the near-wellbore region. Our understanding of these processes and our associated predictive capabilities have been limited by continuum modeling approaches and difficult-to-perform experimental studies. Continuum models overlook the detailed solid-fluid interactions from which macroscopic system properties and behavior emerge, while experimental inquiries have been thwarted by the fine scale and complexity of these many-body systems. An alternative approach is to simulate the near-wellbore region at the grain scale.

However, until recently, the direct simulation of these dynamic, three-dimensional solid-fluid systems has proven computationally intractable. Rapid increases in computational resources, combined with the development of efficient and robust modeling schemes, are ushering in an exciting era of simulation-based discovery in the behavior and prediction of near-wellbore mechanics.

Leveraging these developments, the goal of this project is to develop an unprecedented computational capability for the direct and high-fidelity simulation of the solid and fluid phases in the near-wellbore region, fully resolving the interaction of individual solid particles (and particle assemblages) with other solid particles and the surrounding oil or water. The project provides petroleum engineers with a computational laboratory that can be used to investigate the physical processes controlling such outstanding challenges as sand production, hydraulic fracture initiation, and wellbore stability in weakly consolidated sandstone formations. Model applications are expected to lead to fundamental insights that will greatly enhance our understanding of wellbore mechanics and stability.

Project Results
A two-tiered industry partnership was established to encourage maximum industry participation. Companies able to commit financial resources to the project have entered into a cooperative research and development agreement (CRADA) with Sandia. To date, ChevronTexaco, Halliburton, and Shell have joined the CRADA.

The numerical formulation and development of the computer codes has been validated. The two-dimensional version of the coupled code, SandFlow2D, has been refined and now supports interactive model setup and visualization for both Darcy and lattice-Boltzmann fluid flow and particle transport simulations.

Benefits
The new computer codes will improve simulation of three-dimensional models fluid flow for near-wellbore areas. This will allow operators to maximize completion practices in the near-wellbore zone.

Project Summary
The initial focus of the project was on the refinement and implementation of the numerical scheme into a powerful, easy-to-use simulation environment for the computational exploration of near-wellbore physics. A serial two-dimensional code has been developed for the simulation of small problems. Further work will focus on two R&D thrusts: 1) model testing and large-scale application of the two-dimensional code in industry-selected problem areas; and 2) continued development of the three-dimensional capability. A parallel two-dimensional version will be developed in the next year for large-scale applications. This code will support the simulation of O (105) particles forced by fluid, enabling the more realistic application of the code to a variety of industry problems. A serial, three-dimensional version of the coupled model was developed in tandem in recognition of the inherent three dimensionality of the problems of interest.

(October 2005)
The project is complete.

$375,000

$240,000 (39% of total)

NETL - Paul West (paul.west@netl.doe.gov or 918-699-2035)
SNL - Ben Cook (bkcook@sandia.gov or 505-844-3795)