دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: on a roller cone bit, a coneshaped steel device from which the manufacturer either mills or forges steel teeth, or into which the manufacturer inserts tungsten carbide buttons. Most roller cone bits have three cones, which roll, or rotate, on bearings as the bit rotates. As the cones roll over the formation, the cutters on the cone scrape or gouge the formation to remove the rock.

n: the motion a bit makes when it does not rotate around its centre but instead drills with a spiral motion. It usually occurs to a bit drilling in a soft or medium soft formation when the driller does not apply enough weight or does not rotate the bit fast enough. A whirling bit drills an overgauge hole (a hole larger than the diameter of the bit) and causes the bit to wear abnormally.

n pi: coverings used to contain flying debris and rock caused by the use of explosives during pipeline ditching.

a flange plate without an opening, normally used as seal-off assurance over an unused line.

n: any assembly of pulleys on a common framework;in mechanics. one or more pulleys. or sheaves. mounted to rotate on a common axis. The crown block is an assembly of sheaves mounted on beams at the top of the derrick or mast. The drilling line is reeved over the sheaves of the crown block alternately with the sheaves of the travelling block. which is hoisted and lowered in the derrick or mast by the drilling line. When elevators are attached to a hook on a conventional travelling block. and when drill pipe is latched in the elevators. the pipe can be raised or lowered in the derrick or mast. See crown block, travelling block.

n: a technique in squeeze cementing in which (1) the zone below the producing interval is perforated and a high pressure squeeze carried out;(2) the zone the producing interval is perforated and squeezed off in a similar manner;(3) the hole is drilled out;and (4) the producing interval is perforated. The purpose of block squeezing is to isolate the producing interval and prevent communication with the sand immediately above and below the producing interval.

a cement squeeze into a area of perforations. Often done initially over the frac pressure.

v: to empty or depressure a vessel. Also called depressure.

to release gas pressure. In a reservoir, blow down is often after the oil recovery phase has been complete and the majority of the gas from the gas cap needs to be recovered.

a conditional surface pressure barrier often consisting of a set of hydraulically operated rams containing equipment designed to grip pipe, seal around pipe, shear off pipe or seal an open hole during drilling or a workover. It may also contain an annular

n: the part of a valve that packs off and encloses the valve stem.

the section of the valve housing that covers the stem and protects the seals.

n: a cash payment by the lessee for the execution of an oil and gas lease by the mineral owner;expressed as dollars per acre. Occasionally, an oil payment or overriding royalty may be reserved as a bonus by a lessor in addition to regular royalty.