Drilling cements

W. J. Detroit. Oil well drilling cement dispersant. Patent US 4846888, 1989. 

The modem technological needs of stmctural materials are not fulfilled entirely by these two types of materials. There is also a need for materials that exhibit properties in between cement and sintered ceramics. That need can be met by CBPC matrix composites—materials that are produced like cements at ambient or at slightly elevated temperatures, but exhibit properties of ceramics. These composites are attractive for many stmctural applications, including architectural products, oil-field drilling cements, road repair materials that set in very cold environments, stabilization of radioactive and hazardous waste streams, and biomaterials. 

Particulates of fly ash are very fine. Some of the silica in the ash is found in the form of small silica spheres, called cenospheres or extendospheres, which make ash a very flowable material. This property not only makes ash miscible in a CBPC slurry, but it reduces the viscosity of the slurry and makes the slurry smooth, easily pumpable, and pourable. This property is a great advantage with CBPC-based drilling cements (Chapter 15). 

The last five chapters of the book are devoted to major applications of CBPCs. Chapter 14 covers CBPC matrix composites that are finding commercial applications in the United States. Discussed in Chapter 15 are drilling cements developed mainly by the U.S. Department of Energy laboratories with industrial collaborations. Applications of CBPCs in the stabilization of hazardous and radioactive waste streams are discussed in Chapters 16 and 17. Finally, recent advances in CBPC bioceramics are covered in Chapter 18. Appendixes A, B, and C compile relevant thermodynamic and mineralogy data that were useful in writing the book. They serve as a ready reference to researchers who venture into further development of CBPCs. 

PVP-Am should be useful for oil recovery processes such as well drilling, cementing, stimulation, and enhanced recovery. 

Inserts bolts into table legs using pin machine pushes table leg against rotating drill Cements precut laminated plastic covering to plywood panels for desktops, countertops, etc. Uses solvent to remove excess cement... 

Drilling cement, baiytes, and many other dusts are blown aroimd the rig as they are used or moved. But the main problem has restdted from grit blasting. As the platforms got older, repainting was foimd to be an accelerating requirement with grit blasting a necessaiy prerequisite. 

For the very first section of the borehole a base from which to commence drilling is required. In a land location this will be a cemented cellar in which a conductor or stove pipe will be piled prior to the rig moving in. The cellar will accommodate the Christmas tree (an arrangement of seals and valves), once the well has been completed and the rig has moved off location (Fig. 3.13)... 

As in the construction industry, piling of the conductor is done by dropping weights onto the pipe or using a hydraulic hammer until no further penetration occurs. In an offshore environment the conductor is either piled (e.g. on a platform) or a large diameter hole is actually drilled, into which the conductor is lowered and cemented. Once the drill bit has drilled below the conductor the well is said to have been spudded. 

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

Once the cementation has been completed the rig will wait on cement (V OC), i.e. wait until the cement hardens prior to running in with a new assembly to drill out the plugs, float collar and shoe, all of which are made of easily drillable materials. 

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. 

When a production or injection well is drilled, it is common practice to cement in place a casing which extends across the reservoir interval. The alternative is to leave the reservoir uncased, in a so-called bare foot completion, which is rarely done. When the drilling department finishes its work on the well, it is often left in the state of a cased hole, as on the left of Figure 9.14. 

Cross flow inside the casing can also be prevented by isolating one zone. However, this may still result in reduced production. Installing a selective completion can solve the problem but is an expensive option. To repair cross flow behind casing normally requires a full workover with a rig. Cement has to be either squeezed or circulated behind the production casing and allowed to set, after which cement inside the casing is drilled out, and the producing zones perforated and recompleted. 

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. 

Welan has similar properties to xanthan gum except that it has increased viscosity at low shear rates and improved thermal stabiUty and compatibihty with calcium at alkaline pH (90). The increased thermal stabiUty has led to its use as a drilling mud viscosifter especially for high temperature weUs. The excellent compatibihty with calcium at high pH has resulted in its use in a variety of specialized cement and concrete appHcations. 

Petroleum. Apart from its use ia petrochemicals manufacture, there are a number of small, scattered uses of lime ia petroleum (qv) production. These are ia making red lime (drilling) muds, calcium-based lubricating grease, neutralization of organic sulfur compounds and waste acid effluents, water treatment ia water flooding (secondary oil recovery), and use of lime and pozzolans for cementing very deep oil wells. 

---