TUFACE has several testing facilities including a Hydrate flowloop, two Cold flowloops, a mini-cold flowloop, a DEH test rig, an autoclave, a Jumper/riser, a low pressure test section and an analytical laboratory that supports these units.
Hydrate Flow Loop
The University of Tulsa hydrate flow loop consists of a 160-ft long 3” schedule 80 stainless steel pipe surrounded by a 5” annular jacket for coolant circulation. Loop pressure is measured at the inlet and outlet of the pump. There are several bulk temperature measurements on the loop. Differential pressures are also measured at different locations. Three fixed densitometers as well as a 50-ft scanning densitometer give measurements of the overall density inside the pipe. Four high pressure view ports allow visual observations inside the pipe. The loop is mounted on a rocking table used to drain fluids or change the flowing angle. A twin-screw multiphase pump (Leistritz) is used to circulate the fluids inside the loop. The hydrates flow loop is controlled by an Allen Bradley system.
The facility is equipped with an auxiliary live oil system that is capable of maintaining loop pressure by adding live oil at the same GOR as the flowing mixture. Also, the system is equipped with a high pressure bladder that can be used to withdraw and replace samples at high pressure. The system can be used to generate hydrates at pressures up to 2200 psi and temperatures as low as 30 F. A combination of the gas charging system, live oil system and high pressure bladder allow the system to operate at a constant GOR, constant volume and/or constant pressure. The current operating capacity is 62.5 gallons (including the deposition spool) which allows easy and accurate control of watercut, liquid loading and gas consumption. A deposition spool (an “inverted-U” pipe configuration) is installed on the hydrates flow loop. It allows complete isolation from the rest of the loop and draining of the fluids to leave only solids that are physically bonded to the wall. It is intended to distinguish between settling particles and a deposit stuck on the pipe. The temperature of this spool can be controlled independent of the rest of the loop. It is also equipped with a high pressure camera system to enter the pipe and perform visual inspection of the pipe wall at the testing condition, as well as a rotating densitometer to measure deposit thickness.
Direct Electrical Heating (DEH) Test Rig
The DEH test rig is equipped with two spools, dry and wet (Figure (a)). The test rig also consists of a gamma densitometer and Isco pumps used for final trimming of the plug to the target permeability. Over 30 tests have been conducted on this test rig using 2, 4 and 8 inch spool pieces that were 30 foot long. To date, gas-water, gas-water-oil and slush plugs have been tested. The test rig is equipped with a fiber optic system (hoop & loop every foot) and 6 thermocouples installed at the top and the other 6 at the bottom.
Cold Flow Loops
The cold flow facility consists of two main 3-inch flowloops. The facility operates at pressures up to 150 psi. It is equipped with a pigging system and two heavy duty chillers that can cool to and maintain -40F. The facility has been used to study wax and ice. A smaller version of the loops was developed to form the mini cold flowloop.
The facility capabilities are outlined below:
- Ability to simulate temperatures from -40 F to 100 F as well as transition from positive to negative thermal gradients to mimic following a volume of oil flowing through the sea pipeline
- Ability to simulate flow rates ranging from 200 to 500 MBOPD with equivalent wall shear stresses
- Ability to maintain constant water content
- Enable continuous monitoring of oil flow velocity at an accuracy of less than 1%
- Visual observations of potential ice buildup in low spots and clapper valve
- Ability to maintain water content of 0.2 % with droplet size distribution of 2 microns
- Ability to simulate flow in uphill and downhill sections +/- 200 inclinations
- Pig launcher and pig receiver to enable single pass pigging, emulsify and recycle pigged fluids
- A 10 psi dP for pushing a 3” pig through the loop
- Ability to conduct isothermal tests at constant water cut with chemicals
- Standby generator to ensure uninterrupted power supply
- Remote web page monitoring of data and flow loop status
Analytical Capabilities
In addition to the pilot scale flow loops and bench scale testing facilities, TUFACE also has an analytical laboratory that supports various studies related to flow assurance. Research scientist and engineers with broad experience in petroleum characterization are a part of the analytical team. TUFACE analytical laboratory is equipped with standard equipment for obtaining analytical data for fluid characterization and quality control as well as data which is relevant for understanding and interpreting flow assurance challenges. Majority of our tests follow ASTM procedures while others are in-house proprietary methods.
In order to understand testing results, a thorough understanding of the test oils and gas phases is essential. Several in-house fluid and gas composition analysis devices are used to characterize the test fluids, test samples and deposits. A gas chromatography (GC) equipped with a TCD detector is available for gas characterization of up to 22 gases including several C6- hydrocarbons, hydrogen, nitrogen, hydrogen sulfide, and CO2. A BR distillation device can be used to obtain TBP data of the crude oil according to ASTM standards for atmospheric and vacuum operations. A high temperature GC equipped with an FID detector and a capillary column can be used for the Simdis of crude oil. This GC can be customized for C60 paraffin analysis.
Other analysis include:
- n-Pentane & n-heptane insoluble Asphaltene analysis
- Saturate, Aromatics, Resins, and Asphaltene (SARA) analysis
- View Cell
- multi-temperature viscosity and density measurements
- salinity evaluation of brine for quality control
- Reid Vapor pressure analysis used to compare flow loop RVP after charge to target RVP
Other typical analytical tests are:
- Wax Appearance Temperature (WAT) & Wax content of crude oils and petroleum waxes. A Differential Scanning Calorimeter (DSC) and a Cross Polar Microscope (CPM) are available for use for the wax analysis. The WAT of a petroleum fluid is useful information for risk evaluation during flow or shut-in in cold environments. The wax content gives an upper limit for the total wax available for precipitation from a crude oil and it can be useful for analyzing the nature of a flowloop deposit.
- Interfacial Tension (ITS) / Surface Tension (ST): Our device can be used to determine the surface tension for crude (or other test fluids), brine (or produced water) and the interfacial tension between their mixtures as a quality check to simulate field conditions, to help understand emulsion stability/instability, and/or to help interpret test results.
- Water content measurement can be carried out in-house using BS&W Centrifuge, Karl Fisher (KF) volumetric titrator or KF columetric titrator. The water content analysis is used to verify flow loop charge as well as analyze the water content of flowing samples or deposits in the loop. The KF columetric titrator can measure down to ppm levels of water while the volumetric titrator can measure up to 100% of water.
