- Industry: Oil & gas
- Number of terms: 8814
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The drop in average reservoir pressure from fluid production. All bounded reservoirs have pressure depletion (a drop in average reservoir pressure) associated with fluid production. Water influx counters this effect in reservoirs that are surrounded or underlain by aquifers. Likewise, the presence of a gas cap can slow pressure depletion.
Industry:Oil & gas
The downward vertical movement of filtrate with time after invasion. In hydrocarbon zones, the filtrate is heavier than the formation fluid. Therefore, in a vertical well, gravity causes the filtrate to sink to the bottom of a permeable zone, while the hydrocarbons move back to the borehole at the top. In a horizontal well, the mud filtrate will sink below the well, leaving hydrocarbons above it. The amount of movement depends, among other factors, on the time since invasion, the fluid mobilities and the difference in fluid densities. <br><br>In water zones, the direction of movement depends on the relative densities of filtrate and formation water. In the more usual case of fresh filtrate and salty formation water, the filtrate will move upwards.
Industry:Oil & gas
The downhole pressure at which a treatment fluid can be injected into a zone of interest. The bottomhole injection pressure is typically calculated by adding the hydrostatic pressure of the fluid column to the surface pump pressure measured during an injection test.
Industry:Oil & gas
The downhole hardware needed to make a log. The term is often shortened to simply "tool. " Measurements-while-drilling (MWD) logging tools, in some cases known as logging while drilling (LWD) tools, are drill collars into which the necessary sensors and electronics have been built. <br><br><br><br>Wireline logging tools are typically cylinders from 1. 5 to 5 in. (3. 8 to 12. 7 cm) in diameter. Since the total length is more than can be conveniently handled in one piece, the logging tool is divided into different sections that are assembled at the wellsite. These sections consist of cartridges and sondes. Different measurements can be combined to make up a tool string. The total length of a tool string may range from 10 to 100 ft (3 to 30 m) or more. Flexible joints are added in long tool strings to ease passage in the borehole, and to allow different sections to be centralized or eccentralized. If the total length is very long, it is often preferable to make two or more logging runs with shorter tool strings.
Industry:Oil & gas
The downhole device used to connect the tool string to the coiled tubing string. Several types of devices with varying principles of operation are commonly used. The primary requirement is provision of an adequate mechanical connection capable of withstanding the necessary tensile and compressive forces, while ensuring efficient hydraulic isolation of the connection between the tool string and the coiled tubing string.
Industry:Oil & gas
The distance from the borehole wall that the mud filtrate has penetrated into the formation. The depth of invasion affects whether a log measures the invaded zone, the undisturbed zone or part of each zone. The term is closely related to the diameter of invasion, the latter being twice the depth of invasion plus the borehole diameter. Depth of invasion is a more appropriate parameter for describing the response of pad and azimuthally focused measurements such as density and microresistivity logs. <br><br>The term is well-defined in the case of a step profile of invasion. In the case of an annulus or a transition zone, two depths must be defined, corresponding to the inner and outer limits of the annulus or transition zone. When the invasion model is not specified, the term usually refers to the outer limit of invasion.
Industry:Oil & gas
The distance from the borehole wall into the formation that the mud filtrate has penetrated. The term assumes equal invasion on all sides of the borehole. It is the diameter of the circle thus formed, with the center being the center of the borehole. The diameter of invasion affects whether a log measures the invaded zone, the undisturbed zone, or part of each zone. The term is closely related to the depth of invasion, being twice the depth of invasion plus the borehole diameter. Diameter of invasion is a more appropriate parameter for describing the response of azimuthally symmetric measurements such as induction, laterolog and propagation resistivity. <br><br>The term is well-defined in the case of a step profile of invasion. In the case of an annulus or a transition zone, two diameters must be defined, corresponding to the inner and outer limits of the annulus or transition zone. When the invasion model is not specified, the term usually refers to the outer limit of invasion.
Industry:Oil & gas
The distance between two points in Euclidian space. Euclidian dimensions are all orthogonal to each other (they are all at right angles to each other) and refer to physical space.
Industry:Oil & gas
The distance between the external surface of the gun assembly and the internal surface of the casing or liner. The gun clearance depends on the position of the gun within the tubular and will vary between phases of shots on any gun unless the gun assembly is centralized. This variation in clearance contributes to variable performance of the perforations. The greater the gun clearance, the smaller the entrance hole-with the effect increasing with depth (pressure).
Industry:Oil & gas
The differential pressure that drives fluids from the reservoir into the wellbore. The drawdown, and therefore the production rate, of a producing interval is typically controlled by surface chokes. Reservoir conditions, such as the tendency to produce sand, may limit the drawdown that may be safely applied during production before damage or unwanted sand production occurs.
Industry:Oil & gas
