Stim-Lab core flow testing department offers simulation of reservoir production and treatment using samples of actual reservoir rock or quarried sandstones. These simulations evaluate the effect of treatment fluids, such as acids, mud filtrate and other fluids on reservoir productivity. The productivity is evaluated by measuring changes in permeability, a term which indicates the ability of a porous media to conduct fluid flow. Comparison of these values before and after exposure to a treatment fluid allows an estimate to be made of the extent of formation damage a particular treatment may create.

Simulations are conducted using specialized equipment which simulates as closely as possible the "down-hole"; conditions of pressure and temperature. The primary instrument used in these studies is the Hassler sleeve core holder. Core plugs of one to two inches in diameter are drilled from formation samples obtained from larger cores taken from the reservoir through coring. These plugs are mounted in the Hassler sleeve which contains a rubber bladder. Pressure applied to the bladder confines the core and prevents fluid movement around the core. End pieces or mandrels confine the core plug axially and contain ports which conduct fluids or gases to the core faces. Highly accurate differential pressure transducers measure fluid pressures on either side of the core. This data combined with flow rate, fluid viscosity, and core dimensions are used to calculate the core permeability.

A typical treatment simulation begins with saturation of the core plug with a brine solution. Most hydrocarbon bearing reservoirs contain a certain percentage of saline water or brine. Hydrocarbon flow through the porous media typically occurs with a residual amount of brine present. Therefore, initial oil permeability measurements are typically made at a residual brine saturation within the core. This initial saturation is either performed by vacuum saturation or by flooding the core first with a synthetic formation brine. The initial permeability is then measured by flowing oil or gas to a steady state condition. The core plug is exposed to the treatment either by direction injection of the fluid, such as matrix acidizing, or by dynamic leak-off, such as mud circulation or fracturing. The regained permeability of the core is then remeasured by flowing oil or gas and this value compared to the initial value to determine the percent regained permeability and extent of formation damage. Numerous variations to this type of study are possible. Typical studies performed include:

• Mud or cement solids and filtrate damage
• Acid stimulation and damage remediation
• Fracturing fluid and additive damage
• Relative permeability changes
• Critical velocity for fines migration

Long core flow studies are conducted using a multi-port Hassler sleeve where permeability can be examined at multiple points across a 10 in. long core for matrix permeability studies. These tests reveal the depth of damage or penetration of a fluid treatment. Specialized flow heads are available which allow complete exposure of the core face for leak-off type treatments with mud and/or gelled fluids. Custom equipment can be manufactured by our resident machinist for specialized studies.

Core Flow Support Tests

Stim-Lab performs a number of tests to evaluate damage and stimulation processes before and after treatment. These include:

• Petrographic analysis of thin sections
• Scanning Electron Microscopy (SEM)
• X-Ray Diffraction Analysis (XRD)
• Rock mechanical properties
• Atomic adsorption analysis of ions in fracture and treatment fluids
• Special core analysis for relative permeability, pore size distribution, and porosity

Put Our Commitment to Work for You

Stim-Lab Inc. is committed worldwide to special core flow testing and analysis, which meet our clients particular needs. This commitment continues in critical areas of formation damage predictions, product evaluations, simulations of completion sequences, acidizing of sandstone and carbonate formations, and the development of effective fracturing fluids and techniques for coalbed methane wells, shale and conventional wells.

Stim-Lab Custom Designed Tests

We specialize in custom core flow testing to match reservoir conditions to determine the impact of various completion procedures and treatments on formation permeability. In addition, Stim-Lab offers core testing related to formation damage, product evaluation, and acid stimulation. A few examples of the myriad of tests routinely performed are step-rate critical velocity, two phase methane/brine permeability retention, dynamic leak-off of muds, fracturing fluids and other gel systems.

To support our formation damage evaluations, we integrate the expertise of our petrology and reservoir analysis group into the testing process. Petrography and log analysis provides geological data for engineering applications. Support equipment performed on the cores include x-ray diffraction, SEM, and thin section analysis.

Capillary suction time tests, emulsion testing, water and oil analysis and metals analysis of effluents are examples of common fluid studies. Stim-Lab also performs stimulation fluid tests to determine gel rheology, break time, viscosity, acid spending, and emulsion and sludge tendencies. Many standard API routine procedures (RP's) are available, including mud and cement testing.

Stim-Lab insures confidential testing for product comparisons and tight-hole work. Secrecy agreements are available to insure the protection of proprietary products. Our core flow personnel will assist with designing tests that help solve tough problems.

Specialized Equipment to Meet Your Needs

Stim-Lab designs and operates specialized equipment for performing these studies and other more complex test sequences. For example, equipment in the core flow laboratory can be coupled with rheology loops for simultaneous rheology and damage studies of specialized fluids, such as crosslinked foams.

Experiments are specially configured to simulate downhole conditions to collect the desired data. Specialized components include: a four port Hassler sleeve, dynamic leak-off heads for full core face exposure, a Multiported radial flow cell and a specialized methane gas system.

Complete core preparation facilities are available, including the ability to drill unconsolidated cores with liquid nitrogen and storing conventional or frozen core samples.

Stim-Lab can perform the following:

• Permeability measurement under in situ, conditions using conventional Hassler sleeves, Multiported Hassler sleeves and radial flow cells.
• Fluid leakoff studies with specialized flow-by core holders and in slot flow with parallel cores.
• Drilling, completion and stimulation fluid damage potential evaluation with core from 1 to 9 inches long.
• Matrix-fluid interaction in sandstone, carbonate and coal by capillary suction time device and core flow apparatus.
• Measurement of clay sensitivity and dissolution kinetics by bench top sequential spending tests and core flow tests in various flow cells.
• Gas permeability, Klinkenberg permeability determination in natural gas and coalbed methane formations by integrated two phase flow equipment.
• Measurement of Forcheimer (non-Darcy) effect by Hassler sleeves and radial flow cells.
• Determination of depth of damage and cleanup using Multiported long-core flow device.
• Carbonate acid reaction rate measurement in parallel plate or rotating disk reactors.
• Paralleled plate cells of 10 square inches and 100 square inches are used to measure post-fracture acidizing conductivity.
• Radial flow experiments for acidizing in both carbonate and sandstone. Multi-ported cell for in-depth permeability monitoring.

Stim-Lab Experienced Engineering Studies

Our team of engineers, chemists and geologists analyze core and surface samples from around the world including:

• Mid-Continent Formations
• California - Elk Hills and Belridge Fields
• Black Warrior Basin
• Ames Hole Impact Crater
• San Juan Basin
• Michigan - Prairie Du Chein
• Alaska - North Slope
• Gulf of Mexico
• North Sea - Gullfaks and Rotliegendes
• Bolivia - Maranon Basin
• South China Sea - larim Basin
• Russia - Western Siberia
• North Africa
• Middle East
• Australia

Equipment Manufacturing

Who would you trust to manufacture and test laboratory equipment? How about the people who use it daily? Because of our experience and advance technology developed over the years, Stim-Lab designs, manufactures and markets equipment for various testing and research situations. Stim-Lab core holders, cells, flow manifolds, and data acquisition and control systems are available for any company or organization. With the purchase of our customized systems is the commitment to meet your satisfaction with installation, on-site training, and technical support by our team of dedicated and experienced personnel.

Core Flow Training

Stim-Lab, Inc., provides complete training on core flow systems at our facility in Duncan, Oklahoma, or our experienced personnel will install and train on-site. Training includes instruction in core preparation, cell loading, test procedures, test calculations, results interpretation, modeling, and system maintenance.