- Settore: Oil & gas
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A cylindrical vessel in which a mud sample can be heated under pressure. Cells, often called bombs, are routinely used for static-aging and hot-roll aging of mud samples. Cells are usually made of metal or metal alloy, such as stainless steel or aluminum bronze, and have open tops. Caps should be fitted with a valve so that gas pressure can be applied and then released before opening the cell. Common sizes are 260 and 500 cm<sup>3</sup>, to accommodate half- and one-barrel equivalent volumes, plus space for thermal expansion. Glass or plastic jars can be used judiciously when pressure is nil and temperature is limited to below about 150掳F (66掳C).
Industry:Oil & gas
A coring fluid formulated with components that are not likely to alter the wettability in the pores of the rock sample and that has low dynamic filtration characteristics. These qualities help retain the core's native properties and can retain some (or all) of the reservoir's fluids (water, oil and gas (gas only if kept under pressure)). Bland water-base fluid is formulated to make the filtrate resemble the connate water in the reservoir. Keeping ionic composition and especially the pH matched to the reservoir water is most important. Thus, strong alkaline agents and clay deflocculants are avoided when designing bland coring fluids. Bland oil-base fluids should contain no water phase, and the base oil should resemble the reservoir oil. (Reservoir crude is used in some cases. ) Amine, amide, phosphonated and sulfonated emulsifiers and the powerful oil-wetting agents are also avoided. Fatty acid soaps are chosen to emulsify the trace of water that is likely to be encountered. Additives that minimize dynamic filtration rate must be chosen. Setting mud density and bit hydraulics to give equivalent circulating density close to the reservoir pressure helps avoid filtrate invasion into the core. Designing core bits to core as fast as possible also limits filtrate invasion ahead of the bit.
Industry:Oil & gas
A copolymer of vinyl acetate (ethylenic polymer) and anhydrous maleic acid (a di-hydroxy acid). The vinyl acetate polymer component is usually high molecular weight. As such, with polar groups on the structure, it is used as a flocculant or bentonite extender.
Industry:Oil & gas
A copolymer of polystyrene (containing sulfonate groups on the ring) and anhydrous maleic acid (a di-hydroxy acid). The sulfonated ring-structure polymer component is anionic and usually low to moderate in chain length and molecular weight. As such, with negative groups on the structure (amount of negativity depending on degree of sulfonation), it is used as a clay deflocculant for bentonite-based water mud. It is especially stable to temperature up to around 400掳F (204掳C), and often used in high-density muds to stabilize rheology. Lignosulfonate is used for this purpose up to about 300掳F (149掳C) and then SSMA polymeric deflocculant is often phased into the mud system for drilling deeper and hotter zones.
Industry:Oil & gas
A copolymer of 2-acrylamido-2methyl propane sulfonate and acrylamide. AMPS polymers are highly water-soluble anionic additives designed for high-salinity and high-temperature water-mud applications. (Alkyl-substituted acrylamide can be used instead of ordinary acrylamide, which lessens its vulnerability to hydrolysis at high temperature and high pH. ) Polymers from 0. 75 to 1. 5 MM molecular weight are suggested for fluid-loss control in these difficult muds. <br><br>Reference:<br>Perricone AC, Enright DP and Lucas JM: "Vinyl Sulfonate Copolymers for High-Temperature Filtration Control of Water-Base Muds," SPE Drilling Engineering 1, no. 5 (October 1986): 358-364.
Industry:Oil & gas
A conventional cement slurry used as the cementitious component of a foamed cement slurry.
Industry:Oil & gas
A contraction of reduction-oxidation, a type of chemical reaction in which one reactant is reduced (gains electrons) while the other is oxidized (loses electrons). Examples of redox mud chemistry are: (1) sulfite anions to remove molecular oxygen, (2) sulfide removal by oxygen or peroxide, (3) air oxidation of lignite to create more humic acid, (4) sulfate reducing bacteria that generate sulfide ions by biological redox reactions, (5) chromate ions being converted to chromic ion in a mud system.
Industry:Oil & gas
A continuous measurement of formation properties with electrically powered instruments to infer properties and make decisions about drilling and production operations. The record of the measurements, typically a long strip of paper, is also called a log. Measurements include electrical properties (resistivity and conductivity at various frequencies), sonic properties, active and passive nuclear measurements, dimensional measurements of the wellbore, formation fluid sampling, formation pressure measurement, wireline-conveyed sidewall coring tools, and others. In wireline measurements, the logging tool (or sonde) is lowered into the open wellbore on a multiple conductor, contra-helically armored wireline. Once lowered to the bottom of the interval of interest, the measurements are taken on the way out of the wellbore. This is done in an attempt to maintain tension on the cable (which stretches) as constant as possible for depth correlation purposes. (The exception to this practice is in certain hostile environments in which the tool electronics might not survive the temperatures on bottom for the amount of time it takes to lower the tool and then record measurements while pulling the tool up the hole. In this case, "down log" measurements might actually be conducted on the way into the well, and repeated on the way out if possible. ) Most wireline measurements are recorded continuously even though the sonde is moving. Certain fluid sampling and pressure-measuring tools require that the sonde be stopped, increasing the chance that the sonde or the cable might become stuck. Logging while drilling (LWD) tools take measurements in much the same way as wireline-logging tools, except that the measurements are taken by a self-contained tool near the bottom of the bottomhole assembly and are recorded downward (as the well is deepened) rather than upward from the bottom of the hole (as wireline logs are recorded).
Industry:Oil & gas
A contamination problem caused by Ca<sup>+2</sup> ions, usually occurring in fresh water, seawater and other low-salinity and low-hardness mud systems. Soluble calcium comes into a mud from various sources: gypsum- or anhydrite-bearing strata, unset cement and hardness ions in make-up water or from an influx of formation water. Ca<sup>+2</sup> can flocculate colloidal clays and precipitate large anionic polymers that contain carboxylate groups, such as an acrylate polymer. On the other hand, some mud types tolerate calcium, in which case calcium is not considered a contaminant.
Industry:Oil & gas
A container, usually made of steel and fitted with a sturdy lock, to store drill bits, especially higher cost PDC and diamond bits. These bits are extremely costly but often small in size, so they are prone to theft.
Industry:Oil & gas
