- Industry: Oil & gas
- Number of terms: 8814
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The chemical CaSO<sub>4</sub>, which occurs naturally as the mineral anhydrite. Gypsum is the dihydrate mineral form, CaSO<sub>4</sub>路2H<sub>2</sub>O. Anhydrite and gypsum (commonly called gyp) are found in the subsurface and drilling even small stringers of these minerals can upset a freshwater or seawater mud. Gyp muds, lime muds and oil muds tolerate these salts best. CaSO<sub>4</sub> is used as a mud treatment when no pH increase is needed to remove carbonate ion contamination in freshwater and seawater muds. (Lime increases pH when added for this purpose. ) Gypsum and lime treatments are often used together to keep pH in the proper range. The test for determining the dissolved and undissolved calcium sulfate in a gyp mud requires two titrations with the strong EDTA reagent and Calver II庐 indicator when performed to API standards. It also requires a retort analysis for water content in the mud in order to calculate CaSO<sub>4</sub> content, lbm/bbl.
Industry:Oil & gas
An additive that kills bacteria. Bactericides are commonly used in water muds containing natural starches and gums that are especially vulnerable to bacterial attack. Bactericide choices are limited and care must be taken to find those that are effective yet approved by governments and by company policy. <br /><br />Bactericides, also called biocides, can be used to control sulfate-reducing bacteria, slime-forming bacteria, iron-oxidizing bacteria and bacteria that attacks polymers in fracture and secondary recovery fluids. In polymers, the degradation of the fluid is controlled, thus avoiding the formation of a large biomass, which could plug the formation and reduce permeability.
Industry:Oil & gas
An extraordinarily poisonous gas with a molecular formula of H2S. At low concentrations, H<sub>2</sub>S has the odor of rotten eggs, but at higher, lethal concentrations, it is odorless. H<sub>2</sub>S is hazardous to workers and a few seconds of exposure at relatively low concentrations can be lethal, but exposure to lower concentrations can also be harmful. The effect of H<sub>2</sub>S depends on duration, frequency and intensity of exposure as well as the susceptibility of the individual. <br />Hydrogen sulfide is a serious and potentially lethal hazard, so awareness, detection and monitoring of H<sub>2</sub>S is essential. Since hydrogen sulfide gas is present in some subsurface formations, drilling and other operational crews must be prepared to use detection equipment, personal protective equipment, proper training and contingency procedures in H<sub>2</sub>S-prone areas. <br />Hydrogen sulfide is produced during the decomposition of organic matter and occurs with hydrocarbons in some areas. It enters drilling mud from subsurface formations and can also be generated by sulfate-reducing bacteria in stored muds. H<sub>2</sub>S can cause sulfide-stress-corrosion cracking of metals. Because it is corrosive, H<sub>2</sub>S production may require costly special production equipment such as stainless steel tubing. <br />Sulfides can be precipitated harmlessly from water muds or oil muds by treatments with the proper sulfide scavenger. H<sub>2</sub>S is a weak acid, donating two hydrogen ions in neutralization reactions, forming HS<sup>-</sup> and S<sup>-2</sup> ions. In water or water-base muds, the three sulfide species, H<sub>2</sub>S and HS<sup>-</sup> and S<sup>-2</sup> ions, are in dynamic equilibrium with water and H<sup>+</sup> and OH<sup>-</sup> ions. The percent distribution among the three sulfide species depends on pH. H<sub>2</sub>S is dominant at low pH, the HS<sup>-</sup> ion is dominant at mid-range pH and S<sup>2</sup> ions dominate at high pH. In this equilibrium situation, sulfide ions revert to H<sub>2</sub>S if pH falls. Sulfides in water mud and oil mud can be quantitatively measured with the Garrett Gas Train according to procedures set by API.
Industry:Oil & gas
An organic acid used in oil- and gas-well stimulation treatments. Less corrosive than the commonly used hydrochloric acid, acetic acid treatments can be more easily inhibited or retarded for treatments of long duration. This is necessary particularly in applications requiring the protection of exotic alloys or in high-temperature wells. In most cases, acetic acid is used in conjunction with hydrochloric acid and other acid additives.
Industry:Oil & gas
An organic acid, properly called 2-Hydroxy-1,2,3-propanetricarboxylic acid, with formula C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>. Citric acid is used to reduce the pH of drilling fluids and hence for treatment of cement contamination. It also acts as a polymer stabilizer.
Industry:Oil & gas
ชนิดของเหลวอินทรีย์ กรดอะซิติก หรือ formic ใช้น้ำมัน และก๊าซดีกระตุ้นการรักษา ใช้ HCl inhibited ที่อุณหภูมิจำกัดค่อนข้างสั้นเวลาถ่ายภาพเนื่องจากความเสี่ยงของการกัดกร่อนเพิ่มขึ้นได้ กรดอินทรีย์ inhibited จะมากน้อยปฏิกิริยากับโลหะกว่า HCl หรือน้ำยาผสมของ HCl และ HF ด้วยเหตุนี้ กรดอินทรีย์โดยทั่วไปใช้เรียบร้อยแล้วที่อุณหภูมิ bottomhole สูงหรือเมื่อครั้งนานติดต่อระหว่างกรดและท่อจำเป็น เช่นระหว่าง perforating กรดอินทรีย์จะใช้เพื่อปกป้องโลหะแปลกใหม่ เช่นอลูมิเนียมหรือชิ้นส่วนที่ชุบโครเมียม
Industry:Oil & gas
น้ำเค็มต่ำก่อตัว น้ำกำลังสดเมื่อนำของต่ำทำให้การตีความบันทึกความต้านทานยาก เค็มที่นี้เป็นสำคัญขึ้นอยู่กับอุณหภูมิและดินเนื้อหา ระหว่างปัจจัยอื่น ๆ แต่โดยทั่วไปจะอยู่น้อยกว่า 10 ppk
Industry:Oil & gas
Water that does not contain divalent cations, such as Ca<sup>+2</sup>, Mg<sup>+2</sup> or Fe<sup>+2</sup> and is therefore suitable for prehydrating bentonite or polymers.
Industry:Oil & gas
A process of exchanging one ion for another ion on a charged, solid substrate, such as a natural clay, zeolite or resin. Cation exchange on clay minerals occurs in muds and during mud testing. In muds, various positive ions (for example, Ca<sup>+2</sup>) on clay surfaces can be replaced by other positive ions (for example, Na<sup>+</sup>) that occur in higher concentration or have a higher affinity for the substrate. In water muds, cation exchange is an ongoing and dynamic process. In mud testing, the methylene blue dye is a cationic dye that goes onto clays in the mud sample being tested to show the extent of cation-exchange capacity. Ion exchange is the basis for clay peptization, which can improve a poorly performing clay.
Industry:Oil & gas
