- 行业: Oil & gas
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A compound of formula CaBr<sub>2</sub> used in conjunction with calcium chloride (CaCl<sub>3</sub>) in completion operations to make solids-free brines with densities in the range 11. 5 to 14. 5 ppg.
Industry:Oil & gas
A compound containing the bicarbonate ion (HCOO<sup>-</sup>). The term is commonly used to refer to the ion itself. Bicarbonates are common constituents of drilling fluids. The ions are in equilibrium with carbonate and CO<sub>2</sub> gas.
Industry:Oil & gas
A compound containing hydroxide anions in association with two or more metal cations. MMH particles are extremely small and carry multiple positive charges. They can associate with bentonite to form a strong complex that exhibits highly shear-thinning properties, with high and fragile gel strengths, high yield point (YP), and low plastic viscosity (PV). MMH is described as a mixed-metal layered hydroxide (MMLH). In the crystal layers, Al<sup>+3</sup> , Mg<sup>+2</sup> and OH<sup>-</sup> ions reside, but due to symmetry considerations, there is not enough room for sufficient OH<sup>-</sup> ions to electrically offset the charges of the two cations. Therefore, a net positive charge exists on the crystal surfaces. Exchangeable anions sit on the positive surface (much the same as cations sit on negative clay surfaces). MMH muds are used as nondamaging drilling fluids, metal-reaming fluids (to carry out metal cuttings) and for wellbore shale control. Being cationic, MMH mud is sensitive to anionic deflocculants and small anionic polymers, such as polyphosphates, lignosulfonate or lignite. <br><br>Reference:<br>Burba JL III and Crabb CR: "Laboratory and Field Evaluation of Novel Inorganic Drilling Fluid Additive," paper IADC/SPE 17198, presented at the IADC/SPE Drilling Conference, Dallas, Texas, USA, February 28-March 2, 1988. <br><br>Fraser L and Enriquez F: "Mixed-Metal Hydroxides Fluid Research Widens Applications," Petroleum Engineer International 64, no. 6 (June 1992): 43-46.
Industry:Oil & gas
A component of a drillstring that provides weight on bit for drilling. Drill collars are thick-walled tubular pieces machined from solid bars of steel, usually plain carbon steel but sometimes of nonmagnetic nickel-copper alloy or other nonmagnetic premium alloys. The bars of steel are drilled from end to end to provide a passage to pumping drilling fluids through the collars. The outside diameter of the steel bars may be machined slightly to ensure roundness, and in some cases may be machined with helical grooves ("spiral collars"). Last, threaded connections, male on one end and female on the other, are cut so multiple collars can be screwed together along with other downhole tools to make a bottomhole assembly (BHA). Gravity acts on the large mass of the collars to provide the downward force needed for the bits to efficiently break rock. To accurately control the amount of force applied to the bit, the driller carefully monitors the surface weight measured while the bit is just off the bottom of the wellbore. Next, the drillstring (and the drill bit), is slowly and carefully lowered until it touches bottom. After that point, as the driller continues to lower the top of the drillstring, more and more weight is applied to the bit, and correspondingly less weight is measured as hanging at the surface. If the surface measurement shows 20,000 pounds (9080 kg) less weight than with the bit off bottom, then there should be 20,000 pounds force on the bit (in a vertical hole). Downhole MWD sensors measure weight-on-bit more accurately and transmit the data to the surface.
Industry:Oil & gas
A commonly used preservative for starch, xanthan gum, guar gum and other natural polymers that are prone to attack by bacteria. It is as a trimer of formaldehyde and has the formula O-CH<sub>2</sub>-O-CH<sub>2</sub>-O-CH<sub>2</sub>. Paraformaldehyde is a white, water soluble powder. When added to a mud in advance of a bacterial inoculation and maintained, paraformaldehyde can effectively control many strains of bacteria. The amount or paraformaldehyde in a mud can be estimated by oxidizing it with sulfite into formic acid and performing an alkalinity titration, according to a procedure published by API.
Industry:Oil & gas
A common and inexpensive measurement of the natural emission of gamma rays by a formation. Gamma ray logs are particularly helpful because shales and sandstones typically have different gamma ray signatures that can be correlated readily between wells.
Industry:Oil & gas
A common anaerobic bacterium, commonly abbreviated SRB, that can convert sulfate ions, SO<sub>4</sub><sup>-2</sup>, into S<sup>-2</sup> and HS<sup>-</sup>, with the concomitant oxidation of a carbon source. The lignite, lignin, tannins, cellulose, starches and fatty acids found in many mud systems are carbon food sources for SRB. Where mud is stored, precautions should always be taken when handling or reconditioning water muds containing lignosulfonates, gypsum (sulfate sources) and starches, cellulose, xanthan gum and lignite (food sources). These muds can harbor SRB and can have high sulfide accumulations. Mud filtrate should be tested with the Garrett Gas Train to determine sulfide concentration in a stored mud, followed by treatments with caustic soda to raise pH and zinc-based scavengers to remove sulfides as ZnS. Before storage of mud, treatment with a bactericide can inhibit SRB growth. Also, circulating mud from time to time, with air entrainment, can retard development of anaerobic conditions. <br><br>Anaerobic bacteria can convert the sulfate or sulfite present in water handling facilities to hydrogen sulfide (H<sub>2</sub>S). This by-product, combined with iron, can form iron sulfide, a scale that is very difficult to remove. SRB occur naturally in surface waters, including seawater. Bacteria accumulation can lead to pitting of steel, and the buildup of H<sub>2</sub>S increases the corrosiveness of the water, thus increasing the possibility of hydrogen blistering or sulfide stress cracking.
Industry:Oil & gas
A colloidal suspension or emulsion of specific organic materials. Certain latices may be used as cement additives. Latex is used to provide gas-migration control, improve durability and improve bonding. It also offers excellent fluid-loss control. Latex additives also impart some acid resistance to cement.
Industry:Oil & gas
A collective term for organic salts made by reacting an aliphatic carboxylic acid with a base. The base can be an alkali-metal hydroxide (NaOH or KOH), alkaline-earth hydroxide (Ca(OH)<sub>2</sub> or Mg(OH)<sub>2</sub>) or oxide (CaO or MgO). Fatty acids are the carboxylic acids often used to make soaps for oilfield applications, such as emulsifiers for oil muds. Aluminum soaps are used as defoamers in drilling fluids. Sodium and potassium soaps are detergents to emulsify oil into water.
Industry:Oil & gas
