Reservoir Pressure Prediction

Physical Sciences : Petroleum

Available for licensing

Inventors

  • Peter Flemings , University of Texas at Austin
  • Baiyuan Gao , University of Texas at Austin

Background/unmet need

The fundamental goal of the petroleum industry is to find and exploit hydrocarbons. In the exploration and production processes, over-pressures (pressures greater than those present in a static body of water) are routinely encountered. To design safe and economic wells, the fluid pressure must be predicted in advance with as much accuracy as possible. Current prediction methods only predict pressures in the low permeability mudstone that surrounds the reservoirs. The dramatic increase in unconventional reservoir development has illuminated a specific challenge: the potential variability between pressure in the mudstone and pressure in the adjacent shale formation. The prevention of over-pressure in wells can be significantly improved by exploiting the relationship between known mudstone pressures and unknown reservoir pressures.

Invention Description

Researchers at The University of Texas at Austin have designed the UTCENTROID program which can be used to simulate the pore pressure within petroleum reservoirs based on an understanding of the pressures present in the bounding mudstones. This program overcomes the challenge of determining reservoir pressure for a complex pressure field surrounded by mudstone. The model uses single-phase flow to describe the flow into and out of the petroleum reservoir. The program incorporates a variety of models to describe the permeability of the bounding mudstone. Additionally, the program’s simulation includes the geometry of the reservoir body.

Benefits/Advantages

  • Overcomes challenge of determining reservoir pressure for a complex pressure field
  • Enables the design of safer, more economic wells
  • Enables the ability to predict how hydrocarbons migrate and are trapped in the subsurface
  • Improves estimation of stable well drilling paths
  • Accounts for the effects of permeability and variable pore pressure profile that are not realized in previous methods

Features

  • Predicts pressure within the reservoir ahead of the drill bit
  • Incorporates the effect of permeability change in the mudstone due to effective stress change around the petroleum reservoir
  • Simulates complex, three-dimensional, reservoir geometries
  • Accounts for the effect of pore pressure that increases non-linearly with depth
  • Predicts the reservoir water phase pressure
  • Predicts the maximum column of hydrocarbons that can be trapped
  • Predicts the contrast between mudstone pressure and reservoir pressure for well design

Market potential/applications

The Canadian Society for Unconventional Gas and Society of Petroleum Engineers have developed a study/model of overpressured shale gas wells, in which it is apparent that productivity declines over time. Additionally, the presence of overpressure in wells can result in blowouts, caving, and lost circulation that result in significant maintenance costs. Service companies can commercialize the proposed program to enhance productivity and safety in overpressured conditions.

Development Stage

Beta product/commercial prototype

IP Status

  • 1 U.S. patent application filed