Reservoir Characterization

AGAT Laboratories Reservoir Characterization Division offers one integrated source for complete formation and reservoir evaluation through a combination of Special Core Analysis (SCAL), Pressure-Volume-Temperature (PVT), Scale and Corrosion Services and Rock Mechanics studies.

AGAT Laboratories has over 30 years of engineering and geological experience in designing and implementing solutions to effectively resolve issues in all facets of drilling, completion and production.


Special Core Analysis (SCAL)

Pressure-Volume-Temperature (PVT) Analysis

Rock Mechanics

Service Descriptions

Special Core Analysis (SCAL)

SCAL is used for reservoir characterization and provides better predictions of reservoir performance from core samples, as well as in evaluating any detrimental effects of subjecting a reservoir to foreign fluids to avoid or eliminate production problems. SCAL enables more accurate predictions for reservoir conditions and performance leading to informed drilling and casing decisions, correcting reserve estimates and enhancing production.

Capillary Pressure Measurements are conducted using heated ultra-centrifuge or mercury injection. This measurement  provides air/brine or oil/brine capillary curves for the valuation of reservoir hydrocarbon saturations. AGAT Laboratories has the expertise to work with both consolidated and unconsolidated core.

Drilling Mud Leak-off Analysis performed to evaluate drilling fluid systems for horizontal and vertical applications. AGAT Laboratories will custom-design projects to accurately simulate any drilling application to counter-act fluid loss, wall collapse and to determine the appropriate use of drilling fluids.

Electrical Properties tests provide high-quality data that relates the electrical properties of reservoir rock to porosity. This is one of the most meaningful ways to obtain reservoir fluid saturations by means of down-hole, wire-hole and electrical resistivity measurements. In this technique, the electrical resistivity of the formation is directly measured by means of a down-hole logging tool. Electrical properties of fluid saturation in rock have always been fundamental in quantitative formation evaluation.

Fluid Sensitivity and Fines Migration tests measure reservoir sensitivity in a three-stage program to determine fluid-fluid and fluid-matrix compatibility as well as to determine the critical velocity for core flood applications.

Project applications include the following:

  • CO2 /Nitrogen Floods
  • Water Floods
  • Miscible Floods
  • Polymer Floods

Liquid Permeability Recovery Tests provide the most accurate evaluation for any detrimental effects of subjecting a reservoir to foreign fluids such as drilling mud, completion or workover fluids, or injection water for water flood implementation.

Permeability is a measure of the ability of a reservoir rock to transmit petroleum fluids and is a critical parameter in the evaluation of the production potential of a hydrocarbon reserve. There are different types of permeability measurements that can be made including:

  • Absolute Permeability: When a reservoir rock contains only one single fluid. Analysis conducted at reservoir conditions and subjected to formation brine will provide a baseline liquid permeability.
  • Effective Permeability: When a reservoir contains more than one fluid. AGAT Laboratories offers measurements of this method to provide permeability values that are closely related to the actual reservoir conditions.

Permeability Regain is a method that ignores the influence of a reservoir fluid and strictly evaluates the test fluid/rock interaction. AGAT Laboratories’ engineers will provide a comparison between different proposed drilling/completion fluids and predict what damage mechanisms may occur. Permeability Regain is often used for evaluating acid stimulation fluids. Our Permeability Regain services include:

  • Gas permeability regain at reservoir condition.
  • Oil permeability regain at reservoir condition.
  • Routine gas permeability regain.

Relative Permeability is a dimensionless term used to adapt Darcy’s Law to multi-phase flow conditions. Relative permeability data is used to design, optimize and analyze oil displacement processes to maximize the economic recovery of oil.  Relative permeability parameters, measured at full reservoir conditions of pressure and temperature, are essential for reservoir simulations to predict recoverable reserves and to evaluate the economic impact of water floods or other enhanced recovery schemes.

AGAT Laboratories offers two methods for obtaining relative permeability data including steady-state and unsteady-state, both in a core plug or core plug stack system. This is available for a two or three fluid system at ambient and reservoir conditions up to 10,000psi and 200C for the following:

  • Water-Oil Relative Permeability
  • Gas-Water Relative Permeability
  • Gas-Oil Relative Permeability

Customized Core Floods; Along with the above studies, AGAT Laboratories can customize core floods to meet our client’s needs and suite their specific type of application. Some examples of this include the following:

  • CO2 / Nitrogen Floods
  • Water Flood
  • Miscible Flood
  • Polymer Flood
  • Expanding Solvent Flood
  • Gas Flood
  • Steam Flood
  • Surfactant Flood

Wettability Evaluation is the tendency of a fluid to spread over a surface of a solid. For reservoir rocks, this depends on affinity of the surface for water and oil. AGAT Laboratories utilizes a combined AMOTT/USBM test procedure that effectively differentiates between mixed and neutral wettabilities in addition to basic oil versus water wet conditions.

Net Overburden Petrophysical Measurements includes routine and net overburden (NOB) porosity and permeability.

Klinkenberg Permeability or equivalent liquid permeabilityis  determined by measuring the gas permeability of a core plug sample at a series of increasing pressures while held at a specific confining stress. The Klinkenberg effect is the observation that the absolute gas permeability is always greater than the absolute liquid permeability as a result of “slip flow” between gas molecules and the solid walls of the porous medium.

Pore Volume Compressibility is used to evaluate the pore volume compressibility, which is the fractional change in pore volume per unit pressure change. The porosity of a core sample is measured at a series of different confining pressures to evaluate the changes in the pore volume as a function of pressure.

Mercury Injection Porosimetry involves the high-pressure injection of liquid mercury into a core sample in order to evaluate the capillary pressure. Advantages of this test are that it can be performed quickly, low permeability samples can be analyzed and uniform sample shapes or sizes not required. The resulting data can also be used to evaluate the pore throat size distribution of the core sample, affording a break-down into micro and macro pores.

Pressure-Volume-Temperature (PVT)

Reservoir fluid studies are conducted on reservoir hydrocarbons acquired through down-hole sampling or the recombination of surface separator samples.  AGAT Laboratories' advanced mercury-free PVT units offer a cleaner and safer alternative to traditional PVT analysis while reducing testing time. Results obtained through PVT are essential for the predication of reservoir performance and product mix throughout the producing life of the reservoir.

Differential Liberation simulates the pressure depletion process, which occurs during production and predicts the changes in fluid properties associated with the evolution of gas from the oil or the condensation of liquids from a rich gas system.

Field Sampling Services are provided by our trained personnel to ensure representative hydrocarbon fluid samples are collected from surface separators or with our downhole sampling tools.

Live Oil Viscosity Tests evaluate the effects on the fluid viscosity both above and below the saturation pressure of the hydrocarbon system to predict any decline in production rates.

Pressure-Volume Relationship Tests document the volumetric changes to the fluid system as the reservoir pressure declines during fluid production.

Single Stage or Multiple Stage Flash Tests are utilized to determine oil and gas ratios along with the multiphase stages that occur during formation pressure, separator pressure and pipeline pressure changes. Multiple incremental reductions in pressure are controlled to determine target gasses that are released.

Rock mechanics

Rock mechanics testing provides key information on the strength and stability of reservoir rocks with respect to drilling, fracturing and production.

  • Acoustic Velocity is a non-destructive analysis to determine the Young’s Modulus and Poisson’s Ratio of a rock sample. Utilizing ultrasonic waves through the core samples, compression and shear wave velocities can be determined.
  • Compressive Strength Testing is a destructive analysis that is used to evaluate the ultimate strength of a core plug sample.
  • Elastic Modulus is a destructive analysis that is used to determine the Young’s Modulus and Poisson’s Ratio of a rock sample.
  • Mohr’s Circle is a destructive analysis used to obtain Coulomb’s Failure Envelope, which represents the strength of the rock at various in-situ confining pressures.
  • Splitting Tensile Strength is used to evaluate the tensile strength of a core sample by indirect means.