Oil and Gas Terms Beginning with “B” — Page 8

The bottomhole assembly (BHA) design for directional drilling is the process of selecting and sequencing the rotary steerable system (RSS) or positive displacement motor (PDM), stabilizers, MWD/LWD collars, and drill… Read more →

A bottomhole choke is a flow restriction device installed in the production tubing string at or near the producing formation perforations — rather than at the surface wellhead — to control the flow rate, wellbore… Read more →

Bottomhole circulating temperature (BHCT) is the temperature of the drilling mud or cement slurry at the bottom of the wellbore during active circulation — a dynamic equilibrium temperature that is substantially lower… Read more →

A bottomhole gas separator (also called a gas anchor , poor-boy separator , or reverse-flow separator ) is a downhole device installed at the bottom of the production tubing string, just above the intake of an… Read more →

A bottomhole heater (also called a downhole electric heater or wellbore heater ) is an electrically powered resistance heating element installed in the producing interval of a viscous oil well to reduce near-wellbore… Read more →

Bottomhole injection pressure (BHIP) is the pressure of the injected fluid at the perforations of an injection well — calculated as the sum of the wellhead injection pressure (WHIP) and the hydrostatic head of the… Read more →

Bottomhole pressure (BHP) is the pressure measured or calculated at a specific depth in a wellbore — typically at or near the midpoint of the producing or injecting interval — and is the fundamental pressure datum from… Read more →

A bottomhole sampler is a pressure-rated cylinder deployed in a wellbore on wireline, slickline, or tubing to collect a representative specimen of the in-situ formation fluid (crude oil, gas condensate, or gas) at or… Read more →

Bottomhole shut-in pressure (BHSIP) is the pressure measured or calculated at the producing or test interval depth in a wellbore after the well has been shut in at surface — a pressure that rises from the flowing… Read more →

Bottomhole shut-in pressure in pressure transient analysis provides the foundational measurement from which WCSB reservoir engineers extract formation permeability, skin factor, initial reservoir pressure, and drainage… Read more →

Bottomhole static temperature (BHST) is the undisturbed temperature of the subsurface formation at a specific depth, equal to the geothermal temperature at that point in the Earth's crust before any thermal perturbation… Read more →

Bottomhole temperature (BHT) in general petroleum engineering usage refers to any temperature measurement acquired at or near the bottom of a wellbore, encompassing the single maximum-reading thermometer (MRT) value… Read more →

Bottoms-up (also written bottom's up or BU in mud logging shorthand) refers to the elapsed time required for a volume of drilling fluid or cuttings to travel from the bottom of the wellbore (at the bit face) through the… Read more →

A bottoms-up mud sample is a drilling fluid specimen collected from the surface return flowline or the bell nipple discharge after exactly one lag time has elapsed following a specific drilling event — a drill pipe… Read more →

Bottoms-up circulation in well control kill operations defines the number of pump strokes and circulating time required to displace the entire drill string fluid volume from the bit to surface during a controlled kick… Read more →

Bottoms-up mud sample collection procedure and field show evaluation at the WCSB wellsite requires the mud logger to collect the lag sample at the precise moment it arrives at the surface flowline based on the… Read more →

In nuclear magnetic resonance (NMR) logging, bound fluid is the pore-water volume that is held in place by capillary pressure or electrostatic clay surface forces and cannot be produced under typical reservoir drawdown… Read more →

Bound water in formation evaluation refers specifically to the water fraction held on clay mineral surfaces by electrostatic attraction between the negatively charged clay platelet surfaces and hydrated cations (Na+,… Read more →

The bound fluid log is the nuclear magnetic resonance (NMR) log product that displays the spatial variation of bound fluid volume index (BVI) and free fluid index (FFI) as continuous depth functions derived from the T2… Read more →

Boundary conditions in reservoir engineering and pressure transient analysis (PTA) are the mathematical constraints placed on the outer edges of the reservoir drainage volume that govern how pressure disturbances… Read more →

A bounded reservoir is a reservoir volume enclosed by no-flow boundaries on all sides — sealing faults, stratigraphic pinch-outs, low-permeability barriers, or the outer limit of the aquifer influence — such that… Read more →

A bow-tie diagram is a process safety risk visualization tool that maps the causal pathways and consequence escalation pathways of a single top event — an unwanted loss-of-containment, loss-of-control, or… Read more →

A bow-spring centralizer is a casing-centering device consisting of curved leaf spring bows (typically 6-8 bows per unit) welded or attached between two stop collars that grip the casing outer diameter, designed to keep… Read more →

The box is the female-threaded half of a rotary shouldered connection (RSC), the heavier-walled, externally relieved end of a drill string tubular component that receives the male pin end of the adjacent component and… Read more →

Box plots (or box-counting analysis, also called fractal box-counting or the box-counting method) in petroleum reservoir characterization refers to the quantitative technique that derives the fractal dimension of a… Read more →

Braided line is a downhole intervention wire composed of multiple individual steel wire strands interwoven in a braided pattern around a central core strand — typically 7 × 7 or 7 × 19 wire rope construction, where 7… Read more →

The brake on a rotary drilling rig is the mechanical or electromechanical device on the drawworks that controls the descent rate of the drill string, casing string, or other heavy loads during the tripping, running-in,… Read more →

Break circulation is the act of re-establishing mud pump flow through the drill string and up the annulus after the drilling fluid has been static for a period long enough for its gel strength to develop — the gel being… Read more →

Break-out (also written breakout ) in drilling operations refers to the mechanical unscrewing and separation of threaded drill string connections on the rig floor during a pipe trip — the inverse of making up… Read more →

Breakdown pressure is the wellbore fluid pressure at which a hydraulic fracture first initiates from the borehole wall — the threshold where the combination of applied wellbore pressure, in-situ formation stresses, and… Read more →