Oil well cement must be strong enough to support the casing and to provide adequate zonal isolation. Before using a cement system in a well, developers must verify its compressive strength through direct measurement.
The OFITE CLF-40 Automated Compressive Load Frame performs destructed compressive strength testing on cement samples. It accepts either 2” cubes (cured in an HTHP Curing Chamber) or cylindrical samples (cured in an Ultrasonic Cement Analyzer). The sample is held between two platens while the instrument steadily increases the pressure. When the sample fails, the software automatically calculates the maximum pressure before failure.
The Ultrasonic Cement Analyzer (UCA) uses the change in velocity of an acoustic signal to determine the compressive strength of a well cement over time. The Static Gel Strength Measurement Device (SGSM) uses a vaned bob submerged in the slurry to determine the static gel strength over time. Together, these two instruments provide a more complete picture of the physical properties of a well cement as the slurry sets.
The all new Model 4005 Automated Twin Cell UCA with optional SGSM automatically controls the temperature and pressure in each cell independently, bringing a new level of precision and control to your cement lab. With the new touch-screen display, you can now run an entire test in standalone mode, without the need for computer software, although the software is still included with the instrument.
OFITE will be exhibiting at the 2018 Global Petroleum Show June 12th – 14th in Calgary, Canada. Stop by booth 1408 and learn about our latest products and services. We will be showing:
Model 4005 Automated UCA/SGSM with automated temperature and pressure control, touch-screen display, and integrated Static Gel Strength Measurement Device.
Model 900 Viscometer, featuring standalone or computer-controlled mode, keypad with digital display, and heat cup and carrying case included.
The MudChecker ES, a solid-state probe that measures the oil, water, and solids content as well as salinity of oil based drilling fluids in just a few minutes.
We will also be discussing our new TLF-112 Triaxial Mechanical Properties Testing System, which measures the compressive strength, Young’s modulus, Poisson’s ratio, and tensile strength (using the indirect Brazilian method) of well cement and the new Multi-Unit Retort, which incorporates five 50 mL retorts into a single instrument for space-saving efficiency.
We will also be discussing our partnership with Salunda Limited to distribute the new MudChecker, a solid state probe that measures the oil, water, and solids content as well as salinity of oil based drilling fluids in just a few minutes. A Salunda representative will be on hand to answer questions and provide hands-on demonstrations. We are excited about the opportunity to bring this new technology to the drilling fluids testing industry.
The mechanical properties of a material describe how that material behaves when subjected to an applied force. When placed in an oil well, cement is subjected to numerous stresses which impact its ability to both protect the casing and maintain zonal isolation. Lateral stresses within the formation threaten to warp and crush the casing. Expansion and shrinkage caused by temperature and pressure cycles cause brittle cement to develop cracks, which place well integrity at risk as the cement debonds from the casing or formation.
There are four primary mechanical properties of cement that oilfield service companies need to understand to predict the behavior of the set cement under downhole stresses:
Cement in an oil well needs to be able to resist the forces found in the formation in order to protect the steel casing around which it is placed. The cement sheath is also required to support the weight of the casing as well as resist perforation operations conducted by wireline operators in preparation for fracturing and stimulation activities. Cement needs to develop an adequate level of compressive strength in order to meet these requirements.
Cement compressive strength describes the ability of hardened cement to resist crush force. Laboratories have multiple options to measure the compressive strength development of a cement design. The most practical and efficient method to accurately calculate the compressive strength is to use an Ultrasonic Cement Analyzer (UCA). The UCA works by sending a continuous sound pulse into the cement slurry. As the cement hardens, the sound pulse travels faster through the cement matrix. The transit time is correlated to the compressive strength of the hardened cement.