Well Cements and Drilling Fluids
UPDATE: December, 2015
Trabits Group has developed a lightweight zeolite-containing well cement using a patented method for intergrinding cement clinker and zeolite. Trabits Group has completed a full-scale production run of the lightweight interground composite well cement at a western U.S. cement plant. Product information may be obtained by contacting Trabits Group at email@example.com
Trabits Group has a Patent License Agreement with Halliburton Energy Services, Inc. which gives Trabits Group, on a worldwide basis, the right to make, use, sell and sublicense for use specialized zeolite-containing cements and zeolite-containing drilling fluids.
The zeolite-containing cement technology developed by Halliburton in Canada under the name VariSealTM has been proven to be a cost-effective, low-density cementing system for reducing equivalent circulating densities and obtaining improved pipe/cement/ formation bonding. The technology has also been shown to provide thermal stability with little or no strength retrogression.
The zeolite-containing drilling fluids technology, also developed by Halliburton, eliminates the need to remove drilling fluid and filter cake from the well bore prior to primary cementing. Zeolite-containing drilling fluids can be activated (set) to seal permeable areas. Causing the zeolite-containing drilling fluid left in the wellbore to set creates more favorable conditions for primary cementing operations.
|U.S. Patent or Publication No.||Title||Date of Patent|
|6,964,302||Zeolite-Containing Cement Composition||November 15, 2005|
|6,989,057||Zeolite-Containing Cement Composition||January 24, 2006|
|7,147,067||Zeolite-Containing Drilling Fluids||December 12, 2006|
|US2007/0032388||Zeolite-Containing Drilling Fluids||February 8, 2007|
|7,219,733||Zeolite Compositions for Lowering Maximum Cementing Temperatures||May 22, 2007|
|7,285,166||Zeolite-Containing Cement Composition||October 25, 2007|
|7,332,026||Cementitious Compositions Containing Interground Cement Clinker and Zeolite||February 19, 2008|
After drilling an oil or gas well a cement slurry composition is introduced in the well bore for cementing the pipe string or casing. This process is known as "primary cementing" with the cement slurry pumped into the annular space between the walls of the well bore and the casing. The cement sets in the annular space which supports the casing and forms an impermeable barrier, isolating the well bore from the surrounding formations.
Changes in well pressure or temperature can produce stress on the cement. Well development activities such as hydraulic fracturing, pressure testing and even oil or gas production can also cause stress on the cement. When the stresses exceed the strength or the expansion and contraction flexibility of the cement, failure results and formation isolation is lost. Neat or pure cement is undesirable due to its incompressible nature with little ability to withstand expansion or contraction. Although a variety of additives can be added to cement to alter physical properties to improve strength and flexibility, many such additives are expensive. Additionally, such cements tend to be "single purpose" blends and may require that several blends be taken to the wellsite for well completion. The zeolite cement technology is designed to allow well operators to adjust cement slurries for changing well conditions without using additional blends or additives.
Drill Core from a Zeolite deposit.
Zeolites are a porous aluminosilicate natural mineral with a structure characterized by a linked, three-dimensional, tetrahedral framework. This three-dimensional structure creates a very high surface area. The framework contains open cavities in the form of channels. Because of these channels zeolites are microporous and have the ability to act as "molecular sieves" to selectively sort molecules based on size exclusion. The channels are typically occupied by water molecules giving zeolites the ability to hold more than 25% of their weight in water.
Zeolites have the ability to absorb and lose water without damage to their framework structure. The porous structure of zeolites can accommodate a wide variety of cations such as Na+, K+, Ca2+, Mg2+ and others. These positive ions are loosely held and can be readily exchanged for others in contact with solution. Different framework structures and different combinations of cations result in more than 40 known naturally occurring zeolites. The more common natural zeolites are analcime, clinoptilolite, chabazite, phillipsite and mordenite.
Zeolite Cement Technology
Dorwin Smith inspects a cement kiln
Not all zeolites are effective in the technology. Some will add compressive strength while others provide water absorption but add no strength. The only way to determine zeolite suitability is by testing for desired characteristics. Proprietary aspects of the technology are the zeolite or zeolites used, the zeolite particle size, and the percentage of zeolite by weight of cement.
Wells drilled through weak formations present challenges to cementing operations where the cementing process can damage the formation and result in lost-circulation. Typically high-cost, low-density cementing using hollow beads or cement foamed with nitrogen is used in weak formation completions. The zeolite cement technology is a non-nitrified cement system that provides low-density, low-viscosity slurries that result in the lowest equivalent circulation densities while maintaining sufficient set properties.
Heavy-oil recovery uses a process of steam assisted cycles to improve production viscosity. The zeolite cement technology is a lightweight system that resists thermal regression to minimize the risk of lost circulation while providing thermal stability. Zeolite cement slurries do not shrink but expand providing improved contact with the well casing.
Quality control is a critical aspect of the technology to ensure consistency. Detailed core drilling is completed on the zeolite deposit prior to mining. Selected intervals of the core samples are tested by X-ray Diffraction to identify the zeolite type and zeolite percentage. During the proprietary micronizing process particle size and particle size distribution must be carefully controlled.
X-ray Diffraction - Ferrierite