- 行业: Oil & gas
- Number of terms: 8814
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A hydrophilic polysaccharide from the seed of the guar plant. It is a galactomannan type of saccharide that is highly dispersible into water and brines of various types and salinity. Its water solutions are non-Newtonian and also can be cross-linked by borax to give very high gel strength for suspension. Such a structure is easily broken by breakers in fracturing fluids, so it serves as a carrier for placing sand far back into fractures. It is also used as a top-hole drilling fluid. Disadvantages of using guar gum include its lack of thermal stability and sensitivity to high pH and bacterial fermentation.
Industry:Oil & gas
A hydrocyclone much like a desander except that its design incorporates a greater number of smaller cones. As with the desander, its purpose is to remove unwanted solids from the mud system. The smaller cones allow the desilter to efficiently remove smaller diameter drill solids than a desander does. For that reason, the desilter is located downstream from the desander in the surface mud system.
Industry:Oil & gas
A hydrocyclone device that removes large drill solids from the whole mud system. The desander should be located downstream of the shale shakers and degassers, but before the desilters or mud cleaners. A volume of mud is pumped into the wide upper section of the hydrocylone at an angle roughly tangent to its circumference. As the mud flows around and gradually down the inside of the cone shape, solids are separated from the liquid by centrifugal forces. The solids continue around and down until they exit the bottom of the hydrocyclone (along with small amounts of liquid) and are discarded. The cleaner and lighter density liquid mud travels up through a vortex in the center of the hydrocyclone, exits through piping at the top of the hydrocyclone and is then routed to the mud tanks and the next mud-cleaning device, usually a desilter. Various size desander and desilter cones are functionally identical, with the size of the cone determining the size of particles the device removes from the mud system.
Industry:Oil & gas
A homogeneous, ultralightweight cement system consisting of base cement slurry, gas (usually nitrogen) and surfactants. Foamed cements are commonly used to cement wells that penetrate weak rocks or formations with low formation-fracture gradients.
Industry:Oil & gas
A historical record of how a bit performed in a particular wellbore. The bit record includes such data as the depth the bit was put into the well, the distance the bit drilled, the hours the bit was being used "on bottom" or "rotating", the mud type and weight, the nozzle sizes, the weight placed on the bit, the rotating speed and hydraulic flow information. The data are usually updated daily. When the bit is pulled at the end of its use, the condition of the bit and the reason it was pulled out of the hole are also recorded. Bit records are often shared among operators and bit companies and are one of many valuable sources of data from offset wells for well design engineers.
Industry:Oil & gas
A hinged mechanism that may be closed around drillpipe or other drillstring components to facilitate lowering them into the wellbore or lifting them out of the wellbore. In the closed position, the elevator arms are latched together to form a load-bearing ring around the component. A shoulder or taper on the component to be lifted is larger in size than the inside diameter of the closed elevator. In the open position, the device splits roughly into two halves and may be swung away from the drillstring component.
Industry:Oil & gas
A high-specific gravity and finely divided solid material used to increase density of a drilling fluid. (Dissolved salts that increase fluid density, such as calcium bromide in brines, are not called weighting materials. ) Barite is the most common, with minimum specific gravity of 4. 20 g/cm<sup>3</sup>. Hematite is a more dense material, with minimum specific gravity of 5. 05 g/cm<sup>3</sup>, per API and ISO specifications. Calcium carbonate, specific gravity 2. 7 to 2. 8, is considered weighting material but is used more for its acid solubility than for density. Siderite, specific gravity around 3. 8, has been used to densify mud, but can cause problems by dissolving into the mud at high pH. Ilmenite, specific gravity of 4. 6 has been used in drilling fluid and cement. Only barite and hematite have API/ISO standards.
Industry:Oil & gas
A high-pressure pipe leading from an outlet on the BOP stack to the high-pressure rig pumps. During normal well control operations, kill fluid is pumped through the drillstring and annular fluid is taken out of the well through the choke line to the choke, which drops the fluid pressure to atmospheric pressure. If the drillpipe is inaccessible, it may be necessary to pump heavy drilling fluid in the top of the well, wait for the fluid to fall under the force of gravity, and then remove fluid from the annulus. In such an operation, while one high pressure line would suffice, it is more convenient to have two. In addition, this provides a measure of redundancy for the operation. In floating offshore operations, the choke and kill lines exit the subsea BOP stack and run along the outside of the riser to the surface. The volumetric and frictional effects of these long choke and kill lines must be taken into account to properly control the well.
Industry:Oil & gas
A high-pressure pipe leading from an outlet on the BOP stack to the backpressure choke and associated manifold. During well-control operations, the fluid under pressure in the wellbore flows out of the well through the choke line to the choke, reducing the fluid pressure to atmospheric pressure. In floating offshore operations, the choke and kill lines exit the subsea BOP stack and then run along the outside of the drilling riser to the surface. The volumetric and frictional effects of these long choke and kill lines must be considered to control the well properly.
Industry:Oil & gas
A highly soluble calcium salt of formula CaCl<sub>2</sub> used to make drilling and workover fluids or brines with a density range from 8. 33 to 11. 6 lbm/gal (1. 39 g/cm<sup>3</sup>) at saturation. CaCl<sub>2</sub> can be blended with other brines, including sodium chloride (NaCl), calcium bromide (CaBr<sub>2</sub>) and zinc bromide (ZnBr<sub>2</sub>). Emulsification of CaCl<sub>2</sub> brine as the internal phase of oil-base or synthetic-base mud is an important use because the brine provides osmotic wellbore stability while drilling water-sensitive shale zones.
Industry:Oil & gas
