- Settore: Oil & gas
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The force per unit area exerted at the bottom of a wellbore when it is closed at either the Christmas tree or the BOP stack. The SIBP is generated by a combination of the hydrostatic pressure from the weight of the liquid in the well and any additional applied pressure. The applied pressure component may be from the formation or from an external source at the surface.
Industry:Oil & gas
The fluid, usually drilling mud, used to force a cement slurry out of the casing string and into the annulus.
Industry:Oil & gas
The flow of fluid across the bottom of the bit after it exits the bit nozzles, strikes the bottom or sides of the hole and turns upwards to the annulus. Modern, well-designed bits maximize crossflow using an asymmetric nozzle arrangement.
Industry:Oil & gas
The fixed set of pulleys (called sheaves) located at the top of the derrick or mast, over which the drilling line is threaded. The companion blocks to these pulleys are the traveling blocks. By using two sets of blocks in this fashion, great mechanical advantage is gained, enabling the use of relatively small drilling line (3/4 to 1 1/2 in. Diameter steel cable) to hoist loads many times heavier than the cable could support as a single strand.
Industry:Oil & gas
The fineness to which cement is ground. Grind also may refer to a specific production of cement, such as the lot number.
Industry:Oil & gas
The exit velocity of the drilling fluid after it accelerates through bit nozzles.
Industry:Oil & gas
The evaluation of various well parameters in an attempt to identify when the pore pressure in a drilling well is changing. A team consisting of geologists, engineers and most of the rigsite personnel usually conducts the hunt. The purpose of a pressure hunt is to detect the pore pressure transition (usually from lower to higher pressure) and safely set casing in the transition zone to maximize wellbore strength. A casing string set too shallow, while eliminating some problems associated with drilling fluid contacting the wellbore wall, may not add strength or aid in drilling deeper, perhaps abnormally pressured formations. On the other hand, if drilling is continued too deep into a transition zone, a kick may be taken that cannot be contained in the open wellbore, causing an underground blowout. The hunt team, therefore, seeks to get into the transition zone far enough to gain wellbore strength without taking a kick.
Industry:Oil & gas
The evaluation of physical properties, usually including pressure, temperature and wellbore trajectory in three-dimensional space, while extending a wellbore. MWD is now standard practice in offshore directional wells, where the tool cost is offset by rig time and wellbore stability considerations if other tools are used. The measurements are made downhole, stored in solid-state memory for some time and later transmitted to the surface. Data transmission methods vary from company to company, but usually involve digitally encoding data and transmitting to the surface as pressure pulses in the mud system. These pressures may be positive, negative or continuous sine waves. Some MWD tools have the ability to store the measurements for later retrieval with wireline or when the tool is tripped out of the hole if the data transmission link fails. MWD tools that measure formation parameters (resistivity, porosity, sonic velocity, gamma ray) are referred to as logging-while-drilling (LWD) tools. LWD tools use similar data storage and transmission systems, with some having more solid-state memory to provide higher resolution logs after the tool is tripped out than is possible with the relatively low bandwidth, mud-pulse data transmission system.
Industry:Oil & gas
The escaping tendency, or vapor pressure, of water molecules in an aqueous solution compared with that of pure water, typically abbreviated a<sub>w</sub>. Activity is expressed mathematically as the ratio of two vapor pressures: a<sub>w</sub> = p/p<sub>o</sub>, where p is vapor pressure of the solution and p<sub>o</sub> is vapor pressure of pure water. The ratio ranges from near 0 to 1. 0 and corresponds to percent relative humidity (% RH) of air in equilibrium with the aqueous solution. For pure water, a<sub>w</sub> = p<sub>o</sub>/p<sub>o</sub> = 1. 00 and RH = 100%. By increasing the concentration of salt (or other solutes) in the solution, a<sub>w</sub> decreases, because vapor pressure of the solution decreases. However, a<sub>w</sub> never reaches zero. Known-activity, saturated-salt solutions are used to calibrate RH meters. Measuring RH of air above an oil mud is a simple way to measure the activity (salinity) of its water phase. Adjusting the salinity of the water phase is a way to control movement of water into or out of shales that are being drilled with an oil mud. Chenevert related a<sub>w</sub> in oil mud to RH above the mud sample and devised a practical test using an electrohygrometer to measure RH, called the "Chenevert Method. "
Industry:Oil & gas
The enlarged and threaded ends of joints of drillpipe. These components are fabricated separately from the pipe body and welded onto the pipe at a manufacturing facility. The tool joints provide high-strength, high-pressure threaded connections that are sufficiently robust to survive the rigors of drilling and numerous cycles of tightening and loosening at threads. Tool joints are usually made of steel that has been heat treated to a higher strength than the steel of the tube body. The large-diameter section of the tool joints provides a low stress area where pipe tongs are used to grip the pipe. Hence, relatively small cuts caused by the pipe tongs do not significantly impair the strength or life of the joint of drillpipe.
Industry:Oil & gas
