A device used to restrict fluid flow to one direction. it consists of a polished sphere, or ball, usually or metal, and an annular piece, the seat, ground and polished to form a seal with the surface of the ball. gravitational force or the force of a spring holds the ball against the seat. flow [...]

The downhole assembly used to lift fluid to the surface by the reciprocating action of the sucker rod string. basic components are barrel, plunger, valves, and hold-down. two types of sucker rod pumps are the tubing pump, in which the barrel is attached to the tubing, and the rod, or insert, pump, which is run [...]

A measurement in the well of the pressure vs. depth. useful for spotting liquid levels, leaks, fluid entries, etc.

A complex, non-newtonian fluid in which the shear force is not proportional to the shear rate. most drilling muds are plastic fluids.

A liquid, usually salt water or oil, but sometimes mud, used in a well when a packer is between the tubing and the casing. packer fluid must be heavy enough to shut off the pressure of the formation being produced, must not stiffen or settle out of suspension over long periods of time, and must [...]

A fluid in which the viscosity remains constant for all rates of shear if constant conditions of temperature and pressure are maintained. most drilling fluids behave as non-newtonian fluids, as their viscosity is not constant but varies with the rate of shear.

Fluid (such as gas, oil, or water) that exists in a subsurface rock formation.

A dilatant, or inverted plastic, fluid is usually made up of a high concentration of well-dispersed solids that exhibits a nonlinear consistency curve passing through the origin. the apparent viscosity increases instantaneously with increasing rate of share. the yield point, as determined by conventional calculations from the direct-indicating viscometer readings, is negative; however, the true [...]

1. to collect a mass of sticky consolidated material, usually drill cuttings, on drill pipe, drill collars, bits, and so forth. a bit with such material attached to it is called a balled-up bit. balling up is frequently the result of inadequate pump pressure or insufficient drilling fluid. 2. in reference to an anchor, to [...]

The amount of the pore volume of a reservoir rock that is filled by water, oil, or gas and measured in routine core analysis.

Distance between well head and point to which fluid rises in the well.

An electric or hydraulic pump on an accumulator that pumps hydraulic fluid under high pressure to the blowout preventers so that they may be closed or opened.

1. a condition in which fluid is free-falling down the well at a faster rate than the pumps can handle.
2. in wireline, trying to pull out of the well faster than the wireline tools are being blown upwards by unexpected pressure.
3. trying to pump out a gas influx before the expansion of gas [...]

A centrifugal device for removing sand from drilling fluid to prevent abrasion of the pumps. it may be operated mechanically or by a fast-moving stream of fluid inside a special cone-shaped vessel. compare desilter.

A device that controls the rate of flow of fluid in a line or opens or shuts off the flow of fluid completely. when open, the sealing surface of the valve is moved away from a seat; when closed, the sealing surface contacts the seat to shut off flow. the direction of movement of the [...]