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Reservoir Rock and Fluid Properties

Competency Statement:

Define the properties of the reservoir rock/fluid system.

Learning Objective:

Upon completing this Learning Module assignment, the participant should be able to
  • define the following reservoir properties and understand their importance in the overall reservoir development scheme:
    • Rock properties: porosity, permeability, fluid saturation, compressibility, anisotropy
    • Fluid properties: phase behavior, PVT relationships, density, viscosity, compressibility, formation volume factor, gas-oil ratio
    • Rock/fluid interactions: wettability, interfacial tension, capillary pressure, relative permeability
  • read and understand wellsite descriptions of recovered core material, evaluate the core handling and preservation techniques employed, and select sample intervals for laboratory analysis
  • generate a procedure for preparing and analyzing selected core samples, specifying the tests to be run and the information to be obtained; describe the laboratory techniques and perform the calculations used for determining rock properties
  • design procedures for obtaining representative surface and subsurface formation fluid samples
  • describe procedures for generating PVT analyses of reservoir fluid samples, and interpret the resulting reports
  • use published correlations to estimate reservoir fluid properties

Assignment Instruction:

In this assignment, you will define the basic rock and fluid properties of a recently discovered reservoir in the Republic of Sucre.

You will be in charge of obtaining representative fluid samples and determining their Pressure-Volume-Temperature (PVT) characteristics. You will also design a coring and core analysis program for a new well, and use the results to define basic rock properties and rock-fluid interactions.

The discovery well, Well 4E1-NE, tested at 1550 STB/D of 35 degree API oil [246 m3/D, 0.85 specific gravity], with a producing gas-oil ratio of 680 SCF/STB [121 m3/m3] and a water cut of about three percent. It is currently on an extended production test.

The second well drilled in this field , Well 5C1-SW, tested all water and was subsequently suspended.

Before your company acquired these drilling blocks, a medium-sized independent had run a series of seismic surveys in the area. Your company purchased these data, from which the Geology and Geophysics departments constructed a subsurface contour map showing the approximate structure boundaries and the top of the Upper Sand.

You are now part of the interdisciplinary team charged with characterizing the reservoir and developing an optimal exploitation strategy. Right now, you do not have much to work with—just the contour map and the well data obtained so far. (You can access this material by clicking on the References that accompany each assignment question.)

What you will need to do at this point, then, is to use the available data to try to define some basic reservoir rock and fluid properties.