Oil and Gas Terms Beginning with “K”

With reference to the spontaneous potential log, the coefficient, K, in the equation relating electrochemical potential to the chemical activity of the mud filtrate and formation water. Ec = - K log10 (aw / amf).The coefficient is equal to kT/e in which k is the Boltzman's constant, e is the electron charge and T is the absolute temperature. K is equal to 71 at 25oC [77oF], 12 from the liquid junction potential and 59 from the membrane potential for a perfect shale.

An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameterprofile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table. The rotary motion from the rotary table is transmitted to the bushing through the pins, and then to the kelly itself through the square or hexagonal flat surfaces between the kelly and the kelly bushing. The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself. Depth measurements are commonly referenced to the KB, such as 8327 ft KB, meaning 8327 feet below the kelly bushing.

A mathematical representation of the principle that a wavefield at a given point in space and time can be considered as the superposition of waves propagating from adjacent points and earlier times. It is an integral form of the wave equation in which the wave function at a point is represented as the sum (integral) of contributions from a surface enclosing the given point. The Kirchhoff equation (also called the Kirchhoff integral) is the basis for Kirchhoff migration.

A method of seismic migration that uses the integral form (Kirchhoff equation) of the wave equation. All methods of seismic migration involve the backpropagation (or continuation) of the seismic wavefield from the region where it was measured (Earth's surface or along a borehole) into the region to be imaged. In Kirchhoff migration, this is done by using the Kirchhoff integral representation of a field at a given point as a (weighted) superposition of waves propagating from adjacent points and times. Continuation of the wavefield requires a background model of seismic velocity, which is usually a model of constant or smoothly varying velocity. Because of the integral form of Kirchhoff migration, its implementation reduces to stacking the data along curves that trace the arrival time of energy scattered by image points in the earth.

A curve used to generate a certain type of fractal geometry. Straight lines are replaced by regular polygons repeatedly. These curves look like a snowflake when displayed graphically and are used to illustrate that a curve has a fractal dimension D>1.

A clustering technique that begins with the assignment of the number of clusters to be found. Points that will represent the centroids of these clusters are then evenly dispersed through the data and moved as if by gravity until they settle into positions in the data clouds and cease to move. This technique is much faster than the hierarchical technique but not as accurate, and is often used in electrofacies analysis when large data sets must be analyzed.

A common two-layer clay that does not swell when exposed to water. Kaolinite is used to make paper, pottery and bricks. It occurs naturally in shale and claystone, and therefore is a common component of drill solids in muds.

A type of topography formed in areas of widespread carbonate rocks through dissolution. Sink holes, caves and pock-marked surfaces are typical features of a karst topography.

A long square or hexagonal steel bar with a hole drilled through the middle for a fluid path. The kelly is used to transmit rotary motion from the rotary table or kelly bushing to the drillstring, while allowing the drillstring to be lowered or raised during rotation. The kelly goes through the kelly bushing, which is driven by the rotary table. The kelly bushing has an inside profile matching the kelly's outside profile (either square or hexagonal), but with slightly larger dimensions so that the kelly can freely move up and down inside.

An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameter profile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table. The rotary motion from the rotary table is transmitted to the bushing through the pins, and then to the kelly itself through the square or hexagonal flat surfaces between the kelly and the kelly bushing. The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself. Depth measurements are commonly referenced to the KB, such as 8327 ft KB, meaning 8327 feet below the kelly bushing.

Referring to the condition that occurs when the kelly is all the way down, so drilling progress cannot continue. A connection must be made, which has the effect of raising the kelly up by the length of the new joint of drillpipe added, so drilling can resume.

A large-diameter (3- to 5-in. inside diameter), high-pressure flexible line used to connect the standpipe to the swivel. This flexible piping arrangement permits the kelly (and, in turn, the drillstring and bit) to be raised or lowered while drilling fluid is pumped through the drillstring. The simultaneous lowering of the drillstring while pumping fluid is critical to the drilling operation.

A mechanical device for rotating the kelly. The kelly spinner is typically pneumatic. It is a relatively low torque device, useful only for the initial makeup of threaded tool joints. It is not strong enough for proper torque of the tool joint or for rotating the drillstring itself. The kelly spinner has largely replaced the infamous spinning chains, which were responsible for numerous injuries on the rig floor.

The naturally occurring, solid, insoluble organic matter that occurs in source rocks and can yield oil upon heating. Kerogen is the portion of naturally occurring organic matter that is nonextractable using organic solvents. Typical organic constituents of kerogen are algae and woody plant material. Kerogens have a high molecular weight relative to bitumen, or soluble organic matter. Bitumen forms from kerogen during petroleumgeneration. Kerogens are described as Type I, consisting of mainly algal and amorphous (but presumably algal) kerogen and highly likely to generate oil; Type II, mixed terrestrial and marine source material that can generate waxy oil; and Type III, woody terrestrial source material that typically generates gas.

A small-diameter channel worn into the side of a larger diameter wellbore. This can be the result of a sharp change in direction of the wellbore (a dogleg), or if a hard formation ledge is left between softer formations that enlarge over time. In either case, the diameter of the channel is typically similar to the diameter of the drillpipe. When larger diameter drilling tools such as tool joints, drill collars, stabilizers, and bits are pulled into the channel, their larger diameters will not pass and the larger diameter tools may become stuck in the keyseat. Preventive measures include keeping any turns in the wellbore gradual and smooth. The remedy to keyseating involves enlarging the worn channel so that the larger diameter tools will fit through it.

The product of formationpermeability, k, and producing formation thickness, h, in a producing well, referred to as kh. This product is the primary finding of buildup and drawdown tests and is a key factor in the flow potential of a well. It is used for a large number of reservoir engineering calculations such as prediction of future performance, secondary and tertiary recovery potential, and potential success of well-stimulation procedures. Obtaining the best possible value of this product is the primary objective of transient well tests. To separate the elements of the product, it is necessary to have some independent measurement of one of them, usually the estimation of producing formation thickness from well logs. Permeability is then calculated, provided that the fluid formation volume factor and viscosity are known. The accuracy of the calculated permeability is entirely dependent on the accuracy of the estimated formation thickness and the fluid properties.

To flow formation fluids into the wellbore in an unplanned fashion, as in "the well kicked during the trip."

To stop a well from flowing or having the ability to flow into the wellbore. Kill procedures typically involve circulating reservoir fluids out of the wellbore or pumping higher density mud into the wellbore, or both. In the case of an induced kick, where the mud density is sufficient to kill the well but the reservoir has flowed as a result of pipe movement, the driller must circulate the influx out of the wellbore. In the case of an underbalanced kick, the driller must circulate the influx out and increase the density of the drilling fluid. In the case of a producing well, a kill fluid with sufficient density to overcome production of formation fluid is pumped into the well to stop the flow of reservoir fluids.

A high-pressure pipe leading from an outlet on the BOP stack to the high-pressure rig pumps. During normal well control operations, kill fluid is pumped through the drillstring and annular fluid is taken out of the well through the choke line to the choke, which drops the fluid pressure to atmospheric pressure. If the drillpipe is inaccessible, it may be necessary to pump heavy drilling fluid in the top of the well, wait for the fluid to fall under the force of gravity, and then remove fluid from the annulus. In such an operation, while one high pressure line would suffice, it is more convenient to have two. In addition, this provides a measure of redundancy for the operation. In floating offshore operations, the choke and kill lines exit the subsea BOP stack and run along the outside of the riser to the surface. The volumetric and frictional effects of these long choke and kill lines must be taken into account to properly control the well.

A high-pressure pump designated for well-kill purposes. Depending on the application, the kill pump may need to be connected to a ready supply of kill fluid should well control be required at short notice.

A mud whose density is high enough to produce a hydrostatic pressure at the point of influx in a wellbore and shut off flow into the well. Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or a blowout. Thus, it is usually made by weighting up some of the mud in the system or in storage by adding barite or hematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how much dilution will be needed in advance of adding weighting material to the mud in the pits.

A mud whose density is high enough to produce a hydrostatic pressure at the point of influx in a wellbore and shut off flow into the well. Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or a blowout. Thus, it is usually made by weighting up some of the mud in the system or in storage by adding barite or hematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how much dilution will be needed in advance of adding weighting material to the mud in the pits.

The SI unit of measurement for density. Mud weights are typically expressed in kg/m3. The conversion factor from lbm/gal to kg/m3 is 120. For example, 12 lbm/gal = 1440 kg/m3.

A unit of measurement for pressure in the International System of Units (SI), symbolized by kPa. The conversion factor from lb/in2 to kPa is 6.9 kPa per lbf/in2 (psi). For example, 5000 psi = 34,500 kPa.

In a gradiomanometer tool, the pressure difference observed when the fluid velocity opposite the upper pressure sensor differs from that across the lower pressure sensor. This difference usually occurs opposite points of fluid entry or exit, and at sudden changes in diameter, such as at the tubing shoe. The result is a sharp deflection on the log that may be misinterpreted as a local change in fluid density.

Liquid condensed by a scrubber following a compression and cooling process.

A statistical technique used with variograms, or two-point statistical functions that describe the increasing difference or decreasing correlation between sample values as separation between them increases, to determine the value of a point in a heterogeneous grid from known values nearby.

The weights assigned to control points in kriging operations to minimize the variance, thus eliminating systematic estimation errors.

A measure of a curve describing the statistical frequency distribution in the region about its mode; the relative "peakedness" of the distribution. This measure is used in the description of wireline curves and in schemes that attempt to correlate them from well to well.