Lafarge Well Cements
Well Drilling Necessitates a Significant Investment
The cost of drilling an oil or gas well can range from the $10,000s to well over $100 million. As drilling technology advances and petroleum reserves diminish, the cost of drilling continues to escalate. To insure the integrity of this investment, an effective well cementing approach is paramount. Well cementing calls for the placement of a cement slurry between the casing and the underground formation. A successful cementing operation will ensure "well life" and long term productive capacity.
Lafarge is a Leading Supplier
Lafarge has been a leading supplier of well cements for over 60 years. For decades, Lafarge Well Cements have set the standard for quality. Lafarge Well Cements are noted for their consistency and exceptional field performance. Indeed, many Lafarge customers involved in the drilling industry use Lafarge Well Cements in their product development and designs.
Lafarge Well Cements are not a commodity. Instead, they are a drilling chemical binder produced with the most advanced process techniques and quality control. Lafarge Well Cements are tested to conform to API Spec 10A requirements. They are also tested with Lafarge's customers' additives to ensure superior field performance in many different applications. All Lafarge Well Cements carry the American Petroleum Institute (API) quality monogram. The use of Lafarge Well Cements can result in less additive use and an efficient and high performing slurry mix. The use of high quality well cements is crucial to long term durability.
THE REASONS FOR WELL CEMENTING
Oil and gas wells are drilled to varying depths in many locations and in many harsh environments around the world. A common thread in all these wells is well cement. Well cement is used to form a hydraulic seal between the well casing and the underground formation. This seal must be free of channels and impermeable to gases if the well is to reach its maximum production capability.
Well cement serves many purposes in the drilling project. Foremost among these is protection of the environment, specifically the underground water tables. Well cement isolates and prevents the production fluids and gases from entering the underground water, thus protecting our water supplies. This is referred to as "zonal isolation."
Structural support is important for the casing pipe and production pipes. Well cement is used to form a sheath between the well bore and the casing pipe. A bond is formed between the underground infrastructure and the pipe, anchoring it in place and lending support for the underground well structure. A proper cement bond protects the underground water tables and eliminates the need for remedial cementing, thus resulting in a well having a long life span.
Long Term Durability
Well cements are used to prevent the deterioration of the underground casing and production pipe strings. In many cases fluids which could cause corrosion are used to stimulate the well production. Well cements protect the casings and production strings against corrosion.
Well cements are vital to the long term "well life." Without well cements a costly investment would very shortly lose value.
QUALITY CONTROL: LABORATORY SUPPORT FOR WELL CEMENTS
Lafarge produces premium well cements at four plants: Joppa, Illinois, and Whitehall, Pennsylvania in the U.S. and Exshaw, Alberta and Brookfield, Nova Scotia in Canada. Each plant is dual-certified to ISO 9001:2000 and to API-10A by the American Petroleum Institute. Each plant is licensed by the American Petroleum Institute and authorized to use the API Monogram for the well cements it produces: API Class A (O), API Class G- HSR, or API Class H-HSR.
The Lafarge plants producing well cements have a specific well cement laboratory which undertakes the following:
Lafarge well cements are produced and tested in strict adherence to the following standards:
Well Cement Testing at the Joppa Plant: The Joppa Oil Well Testing Laboratory is an example of the type of testing carried out by Lafarge. Testing capabilities exceed those required to satisfy API Spec 10A requirements. The Joppa Oil Well Laboratory routinely performs:
Quality Management System (QMS): At the four Lafarge plants manufacturing well cements
All of the Lafarge plants in North America producing well cements have comprehensive Quality Management Systems (QMS) in compliance with the internationally recognized standard API Specification Q1, 7th Edition, "Specification of Quality Programs for the Petroleum and Natural Gas Industry". API Specification Q1 corresponds to and exceeds the requirements of ISO 9001-2000.
The QMS of each of the Lafarge plants in North America producing well cement is audited annually by the Monogram Program of American Petroleum Institute (API) located in Washington, D.C. These external QMS audits determine the effectiveness of the QMS as well as the ability of the plant to manufacture and test the cement in accordance with API Spec 10A "Specifications for Cements and Materials for Well Cementing". Completion of a successful audit is confirmed by the issuance of the "Certificate of Authority to use the Official API Monogram."
The Quality of Well Cements Begins at the Quarry
Quarrying and Raw Grinding
The quality of well cements begins with the selection of raw materials. Raw materials must contain appropriate proportions of calcium, silica, alumina and iron components. In the dry cement manufacturing process the raw materials are proportioned into the raw mills where they are finely ground. From the raw mill, the product - now called raw meal or raw mix - is transferred to blending silos. In the blending silos, a homogenous mix of the raw meal is prepared and tested. When the raw meal meets the full quality requirements, it is then transferred to the kiln feed silo. Now the raw meal, called kiln feed, and is ready for firing (clinkering) in the kilns.
Pyro-Processing in the Kiln
The ultimate quality of well cements is achieved after the conversion of the kiln feed to clinker. Clinker is formed in the kiln as the kiln feed is heated to temperatures approaching 15400 C (28000 F). During this burning process the kiln feed is converted into micron-sized crystals (cement compounds). The characteristics of these crystals determine the reactivity of the finished cement. A microscope is used to evaluate the clinker microstructure. Changes in burning conditions are made to optimize the reactivity of the clinker. Quality control steps taken during the burning process are extremely important parameters in producing well cement.
After the burning process, the clinker is stored in clinker bins, or silos. An additional quality step is the blending of the well cement clinker. The final process is grinding the clinker in finish mills to produce well cement. During grinding, the mill is closely monitored for milling temperatures and particle fineness. Gypsum is added to control the aluminate and ferrite reaction during hydration. Chemical checks of the cement are routinely performed during grinding to control, and ensure, the proper gypsum addition rate. The finished cement passes from the finish mill to large cement storage silos and held for shipment.
Schematic illustrating a cemented borehole
Oilfield cement testing lab
Inside of a cement kiln
Cement crystals under a microscope