Core flood systems are some of the most versatile lab equipment used in the oil and gas industry. Some of the many applications that a DCI core flood system can be used for include:
EOR test and research
Formation damage test
Relative permeability measurements
Steady state permeability measurements
Flow distribution in multi-layered reservoirs
Diversion of stimulation fluids
Drilling mud invasion
The core holder encloses the core sample and subjects it to simulated reservoir conditions. Some of the options that are available in a core flood system include:
Single or dual core holders
Pivoting mount frame for horizontal or vertical orientation
Roller-supported mount frame for easy movement and maintenance
Pivoting mount to move from inside to outside oven for sample loading.
Radial confining pressure, hydrostatic, or triaxial loading capability
Range of core diameters (1”, 1 ½”, 2”)
Core lengths up to 12”
Multi-tap pressure ports along the core length
Imbedded sensors along length of core holder sleeve.
Upstream Flow System
DCI has designed a family of dual piston syringe pumps (VPA) specifically for core flood applications. These pumps use special algorithms to provide pulse-less flow to drive fluid separator accumulators. Some of the features that can be selected to meet specific test requirements include:
Pressure range and flow rate for the VPA(s)
Multiple VPA’s to allow simultaneous multi-phase flow
Flow path forward or reverse, or in parallel or series through multiple core holders
Wetted parts: Stainless steel or Hastelloy C 276
Tubing size: 1/16”, 1/8”, or 1/4”
Gas injection system
One option is a custom designed, stainless steel oven that houses the core holder(s) and fluid separators. This allows core flooding tests to be conducted routinely to 150°C. With special seal materials and other modifications to components, tests to 200°C are possible. Other options to heat components to reservoir temperatures include heating jackets and rod heaters.
A bank of piston-type accumulators is mounted in the oven to allow multiple fluids to flow through a core sample in sequence or simultaneously. Air operated automatic valves, also in the controlled temperature environment, allow the active accumulator(s) to be selected or be filled without disturbing the temperature environment. The separators are driven by one or more VPA’s. The separators provide capability to flow highly corrosive fluids through the core sample(s) without putting the corrosive fluid in contact with the VPA. Typical specifications for the fluid separators are:
Wetted parts: Hastelloy C 276, Titanium, Stainless Steel, Teflon, and PEEK
Volume: 20 to 2000 ml
Pressure: Up to 20,000 psi
Confining Pressure Control
The pressure control system controls the confining pressure around the core sample and, if applicable, the axial pressure applied to the core sample. Some options include:
Pressure: Up to 20,000 psi
“Passive” pressure control with isolation valves
“Active” pressure control with back pressure regulator or VPA
Separate axial pressure control
Differential Pressure Measurement Module
Accurate differential pressure measurement is the key to accurate permeability and other flow parameter calculations. These measurements include differential pressure measurements over the length of the core and between ports on core holders with multi-tap pressure ports. Selecting the optimum differential measurement transducer(s) depends on the differential pressure to be measured as well as the system pressure rating. DCI engineers can help select the optimum differential pressure transducers for a specific application. A proprietary DCI design uses dual quartz pressure transducers with one part per billion resolution capability and an air-operated shorting valve between the two transducers to provide extremely accurate and stable differential pressure measurement.
Back Pressure Control and Fluid Sampling System
The back pressure control system controls the downstream pore pressure in the system and provides a means of measuring flow rates and volumes of fluids flowing through the core(s). Options include:
VPA in pressure mode to control back pressure and measure volume.
Dome-loaded back pressure regulator
VPA and Acoustic Separator using CFAS™
Coriolis mass flow meter.
Data Acquisition and Test Control System
Data is acquired automatically from each transducer in the system. This PC-based system allows the operator to specify which data are collected for a specific test as well as the data collection rate. The same PC program provides test control capability for the system. A touch-screen interface allows the operator to set the flow configuration, the back pressure control mode, the active accumulator, the oven temperature, the VPA control mode and other test parameters. The flow configuration and other test parameters are displayed graphically to the operator. Other screens allow for functions such as individual control of automated valves for maintenance purposes, entry of transducer calibration values, and more. This data acquisition and test control software is typically customized to each specific test system.