- Industry: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
- Company Profile:
The upside down V-shaped opening in one side of the derrick that enables long pipes and tools to be lifted into the interior of the derrick. This opening is aligned with the slide and catwalk of the rig.
Industry:Oil & gas
The uncontrolled flow of reservoir fluids from one reservoir into the wellbore, along the wellbore, and into another reservoir. This crossflow from one zone to another can occur when a high-pressure zone is encountered, the well flows, and the drilling crew reacts properly and closes the blowout preventers (BOPs). Pressure in the annulus then builds up to the point at which a weak zone fractures. Depending on the pressure at which the fracturing occurs, the flowing formation can continue to flow and losses continue to occur in the fractured zone. Underground blowouts are historically the most expensive problem in the drilling arena, eclipsing the costs of even surface blowouts. It may prove necessary to drill a second kill well in order to remedy an underground blowout.
Industry:Oil & gas
The uncased portion of a well. All wells, at least when first drilled, have openhole sections that the well planner must contend with. Prior to running casing, the well planner must consider how the drilled rock will react to drilling fluids, pressures and mechanical actions over time. The strength of the formation must also be considered. A weak formation is likely to fracture, causing a loss of drilling mud to the formation and, in extreme cases, a loss of hydrostatic head and potential well control problems. An extremely high-pressure formation, even if not flowing, may have wellbore stability problems. Once problems become difficult to manage, casing must be set and cemented in place to isolate the formation from the rest of the wellbore. While most completions are cased, some are open, especially in horizontal or extended-reach wells where it may not be possible to cement casing efficiently.
Industry:Oil & gas
The total time required for pumping the cement slurry into the well, plus a safety factor. Pumping time can also be the time required to reach a consistency deemed to be unpumpable (generally 70 Bc) during an API thickening-time test.
Industry:Oil & gas
The time taken for cuttings to reach the surface. The term is also used in place of cycle time.
Industry:Oil & gas
The tool used to crush or cut rock. Everything on a drilling rig directly or indirectly assists the bit in crushing or cutting the rock. The bit is on the bottom of the drillstring and must be changed when it becomes excessively dull or stops making progress. Most bits work by scraping or crushing the rock, or both, usually as part of a rotational motion. Some bits, known as hammer bits, pound the rock vertically in much the same fashion as a construction site air hammer.
Industry:Oil & gas
The total force pulling down on the hook. This total force includes the weight of the drillstring in air, the drill collars and any ancillary equipment, reduced by any force that tends to reduce that weight. Some forces that might reduce the weight include friction along the wellbore wall (especially in deviated wells) and, importantly, buoyant forces on the drillstring caused by its immersion in drilling fluid. If the BOPs are closed, any pressure in the wellbore acting on the cross-sectional area of the drillstring in the BOPs will also exert an upward force.
Industry:Oil & gas
The threaded collar used to connect two joints of casing. The resulting connection must provide adequate mechanical strength to enable the casing string to be run and cemented in place. The casing collar must also provide sufficient hydraulic isolation under the design conditions determined by internal and external pressure conditions and fluid characteristics.
Industry:Oil & gas
The term used to describe how off-center a pipe is within another pipe or the openhole. It is usually expressed as a percentage. A pipe would be considered to be fully (100%) eccentric if it were lying against the inside diameter of the enclosing pipe or hole. A pipe would be said to be concentric (0% eccentric) if it were perfectly centered in the outer pipe or hole. Eccentricity becomes important to the well designer in estimating casing wear, wear and tear on the drillstring, and the removal of cuttings from the low side of an inclined hole. In the latter case, if the drillpipe lies on the low side of the hole (100% eccentric), the eccentricity results in low-velocity fluid flow on the low side. Gravity pulls cuttings to the low side of the hole, building a bed of small rock chips on the low side of the hole known as a cuttings bed. This cuttings bed becomes difficult to clean out of the annulus and can lead to significant problems for the drilling operation if the pipe becomes stuck in the cuttings bed.
Industry:Oil & gas
