Cementing fluids

J. F. Baret. Why cement fluid loss additives are necessary. In Proceedings Volume, pages 853-860. SPE Petrol Eng Int Mtg (Tianjin, China, 11/1-11/4), 1988. 

L. K. Moran and T. R. Murray. Well cement fluid loss additive and method. Patent US 5009269,1991. 

D. T. Muller. Performance characteristics of vinylsulfonate-based cement fluid-loss additives. In Proceedings Volume, pages 609-617. SPE Rocky Mountain Reg Mtg (Casper, WY, 5/18-5/21), 1992. 

P. Schilling. Aminated sulfonated or sulfomethylated lignins as cement fluid loss control additives. Patent US 4990191, 1991. 

S. Schilling. Lignin-based cement fluid loss control additive. Patent US 4926944, 1990. 

Petroleum production In drilling muds, cementing fluids, hydraulic fracturing fluids, workover fluids, completion fluids, pipeline cleaning fluids, and enhanced recovery fluids... 

An interesting and separate application proposed for borate is as a component of a cement fluid loss additive. Cements require a minimum amount of water for proper hydration and setting and if water from the cement filters into the formation, the setting process can be compromised. Cements therefore contain fluid loss additives. A dried, preformed borate cross-linked polyvinyl alcohol (PVA)-sorbitol complex has been proposed for use as a fluid cement fluid loss additive [100]. This may have wider application in other oil well fluids. 

Eikenberg Lichtner (1992) Model 50000 a Muscovite -chlorite marl Cement fluids Mostly feldspars zeolites up to 3 km from site Plume front propagates slowly and retains a steep pH gradient... 

A third important alteration process in cement/rock interaction is the precipitation of calcite and other carbonates and sulphates. This happens when calcium hydroxide-rich cement fluids come into contact with various sources of carbonate and sulphate, such as local ground-waters or carbonate and sulphate phases already present in the rock which may dissolve when the highest pH fluids are encountered. Calcite precipitation due to these processes has been predicted by models (Jefferies et al. 1988 Lunden Andersson 1989 Eikenberg Lichtner 1992 Steefel Lichtner 1994). Calcite has also precipitated in some experiments, even if attempts were made to keep carbonate and CO2 out of the system (e.g. Pusch 1982 Jefferies et al. 1988). 

In Hadrian s Wall, mineral/cement fluid reactions in the dolerite produced a zone of increased porosity (caused by dissolution) and a deeper, parallel zone in which macroporosity was unchanged due to replacement by reaction products. The combined effect is to increase the surface area of solid material (dolerite or reaction product). This could increase the extent of any subsequent matrix/fluid interaction. 

Collapse load originates from the hydrostatic pressure of drilling fluid, cement slurry outside the casing and later on by moving formations e.g. salt... 

Sometimes primary cementations are not successful, for instance if the cement volume has been wrongly calculated, if cement is lost into the formation or if the cement has been contaminated with drilling fluids. In this case a remedial or secondary cementation is required. This may necessitate the perforation of the casing a given depth and the pumping of cement through the perforations. 

The chemistry of cement slurries is complex. Additives will be used to ensure the slurry remains pumpable long enough at the prevailing downhole pressures and temperatures but sets (hardens) quickly enough to avoid unnecessary delays in the drilling of the next hole section. The cement also has to attain sufficient compressive strength to withstand the forces exerted by the formation over time. A spacer fluid is often pumped ahead of the slurry to clean the borehole of mudcake and thereby achieve a better cement bond between formation and cement. 

Polyacrylamides are used in many other oilfield appUcations. These include cement additives for fluid loss control in well cementing operations (127), viscosity control additives for drilling muds (128), and fracturing fluids (129). Copolymers [40623-73-2] of acrylamide and acrylamidomethylpropanesulfonic acid do not degrade with the high concentrations of acids used in acid fracturing. 

Searching a crime scene is a complex process (25), involving poHce, crime scene technicians, and forensic scientists. The procedure requires careful documentation, collection, and preservation of the evidence. Trace evidence (26) in criminal investigations typically consists of hairs (27,28) both natural and synthetic fibers (qv) (29,30), fabrics glass (qv) (31,32) plastics (33) sod plant material budding material such as cement (qv), paint (qv), stucco, wood (qv), etc (34), flammable fluid residues (35,36), eg, in arson investigations explosive residues, eg, from bombings (37,38) (see Explosives and propellents), and so on. 

The calcium chelate cements are limited to the use of a cavity liner. They may be placed directly over an exposed tooth pulp to protect the pulp and stimulate the growth of secondary dentin, or used as a therapeutic insulating base under permanent restorations. The high alkalinity and high solubihty of these materials prohibits use in close proximity to soft tissues or in contact with oral fluids. 

The chelated calcium cementing materials are suppHed as two-part paste products. In use, equal parts of the two pastes are thoroughly mixed together to give a fluid mass that can be appHed without pressure over an exposed tooth pulp or in a deep-seated cavity. Under the influence of the oral temperature and humidity, the fluid mass sets to a hard, strong, therapeutic protective seal. 

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