Well Completion and Stimulation in Unconsolidated Sands

Mukul M. Sharma

Well completion and stimulation in unconsolidated formations has wide implications for the US petroleum industry. Most of the production in the Gulf of Mexico comes from unconsolidated sands. Frac-pack completions are being frequently performed in poorly consolidated, high-permeability sand formations to bypass well damage and enhance productivity. Despite the significance of the production from unconsolidated sands for the US, the design and placement of these completions in these sands is often sub-optimal due to lack of proper design tools.

The existing models for predicting fracturing in unconsolidated sands assume, to a lesser or greater extent, the theory of Linear Elastic Fracture Mechanics for fracture propagation. However, for very soft, ductile formations, the assumptions of linear strain with no significant plastic deformation are not valid. Measurements of the stress-strain behavior of unconsolidated sands conducted in our labs indicate elasto-plastic behavior. The primary objective of this proposal is to develop entirely new models for fracturing in unconsolidated sands through a better understanding of the mechanisms of fracturing in such sands. We propose to achieve this by the dynamic coupling of three models for modeling three concurrently occurring phenomena: a pore-pressure propagation model to obtain pore-pressure distribution, a geomechanical model relating poro-elastic stresses to permeability changes, and a model for particle plugging to account for permeability reduction due to particles in the fracturing fluid (gels, proppants etc.).

This proposal proposes theoretical / experimental lab studies combined with analysis of field results to gain insights into the problem. The models will be tested with field data to confirm the efficacy of the models. It is anticipated that the improved design would increase the well productivity up to 50%.

Sponsoring Organizations

  1. The University of Texas at Austin
  2. Conoco
  3. Shell International Exploration and Production

Contact:

Mukul M. Sharma
Center for Petroleum and Geosystems Engineering
1 University Station C0304
The University of Texas at Austin
Austin, Texas 78712-0228
Phone: (512) 471-3257 FAX: (512) 471-9605
Email: msharma@mail.utexas.edu

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