| A successful fracturing treatment is highly dependent upon the rheological properties of the fracturing fluid. Fluids with insufficient viscosity will not completely transport the proppant into the formation, thus favoring a poor fracturing treatment. In the design of the treatment, it is imperative to accurately predict the frictional pressure losses. These estimates are highly dependent upon laboratory data. Cross-linked polymers with high apparent viscosities are commonly used as fracturing fluids and the magnitude of the viscosity makes it difficult to measure the shear stress with a conventional rotational rheometer. Research engineers have determined that the best method to measure the rheological properties of a fracturing fluid is by the utilization of a pipe rheometer. Shear stress and shear rate may be calculated by measuring the frictional pressure loss created by flowing a fluid at a constant flow rate through a pipe of known length and diameter.
Naturally, in the application of dimensional similitude analysis, the closer the scale model to the actual application, the more accurate the test results. Unfortunately, constructing a full scale model of a well would be cost prohibitive and impractical. OFITE developed the Model 320 Pipe Rheometer to provide a means for engineers to accurately determine the rheological properties of fracturing fluids. Applying precise data with a minimal scaleup factor makes it possible to achieve more reliable frictional pressure loss estimates and improved fracturing treatments.
Method of Operation:
A polymer, usually either HPG or guar, is mixed in the 500 gallon tank with the lightening mixer. The crosslinker is poured into the 30-gallon reservoir and the metering pump is adjusted to the required crosslinker loading. The progressive cavity fluid delivery pump is regulated to the desired flow rate. The heating system is set to the desired temperature and allowed to reach test temperature. The crosslinker additive pump is started and the crosslinker is added to the polymer fluid just before the fluids enter a static mixer, which ensures that the polymer and crosslinker are thoroughly mixed. The fluid mixture is normally pumped through the shearing coil before testing the fluids in the pipe rheometers. However, valves are installed so that the fluid may be diverted directly to the pipe rheometers. The differential pressure is measured across the length of each pipe rheometer (20 feet) via pressure transducers. The temperature is measured via thermocouples. Valves may be adjusted so that the fluid may be disposed of or re-circulated for further investigation. All measured variables are digitally displayed and recorded on a multi-channel strip chart recorder. An optional data acquisition system is available, which utilizes a personal computer to measure and record data.
Features and Specifications:
- Powerful 10 horsepower motor
- Variable-speed controller for motor
- Progressive cavity pump with maximum flow rate of 40 gpm
- Temperature (350ºF maximum) maintained via PID controller
- Process temperatures displayed digitally
- Three 316 stainless steel pipe viscometers (0.25", 0.5" & 1.00")
- Temperature measured via thermocouple
- Differential pressure transducers measure Delta P
- Six-channel strip chart recorder provides hard copy of data
- Precision metering pump delivers crosslinker
- Meters measure the flow rate of each viscometer tube, 0.5" diameter, 200 ft shear history coil
- All wetted components manufactured from 316 SS
- All necessary tools and calibration equipment included
Options:
A Data Acquisition System (DAS) is available for OFITE’s Pipe Rheometer. This option utilizes an IBM-compatible computer with a 13" color monitor, and an Epson printer to measure, record, display, and print all necessary data. In addition, measured variables are graphically displayed and the included software calculates all important parameters to permit for professional presentation of results.
Instrument Requirements:
- 40 psi 10 gpm water supply
- Water drain
- 220 Volt, 50/60 Hz, 20 KVA power source
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