- Branża: Oil & gas
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A form of homogeneity in a single characteristic. Local stationarity occurs when two or more adjacent, locally homogeneous samples yield similar values of the property of interest.
Industry:Oil & gas
A fluid-flow regime characterized by swirling or chaotic motion as the fluid moves along the pipe or conduit. The linear velocity of the fluid particles is similar regardless of position in the conduit, although particles close to the conduit walls have a lower velocity. This characteristic makes turbulent flow an efficient flow regime for the pickup and transport of solids. However, the potential for erosion may be significant, especially with abrasive fluids and a tortuous flow path.
Industry:Oil & gas
A form of fractal geometry based on a triangle. It has a fractal dimension D = ln 3/ln 2 = 1. 58. . . . <br>A Sierpinski carpet uses a square instead of a triangle and has a fractal dimension D = ln 8/ln 3 = 1. 89. . . .
Industry:Oil & gas
A fluid, generally a liquid, comprising more than one phase, such as water- or oil-based liquids, solid material or gas. Multiphase fluids and their behavior are of concern in two main areas, the flow of multiphase fluids and the separation of the various phases at surface.
Industry:Oil & gas
A fluid, generally water-based, to thin and disperse mud in preparation for cementing. The chemical wash is pumped ahead of the cement slurry to help ensure effective mud removal and efficient cement placement. Other specialized chemical washes may be used in the remedial treatment of scales or paraffin deposits in production tubulars.
Industry:Oil & gas
A fluid that is used to transport materials into or out of the wellbore. Carrier fluids typically are designed according to three main criteria: the ability to efficiently transport the necessary material (such as pack sand during a gravel pack), the ability to separate or release the materials at the correct time or place, and compatibility with other wellbore fluids while being nondamaging to exposed formations.
Industry:Oil & gas
A fluid stage, normally hydrochloric acid (HCl), pumped ahead of the main treating fluid (mixture of hydrofluoric (HF) and hydrochloric (HCl) or organic acids) in a sandstone matrix-stimulation treatment. One of the purposes of a preflush is to displace formation brines that contain K, Na, Ca ions away from the wellbore, decreasing the possibility of crystallizing alkali-fluosilicates that could plug the pores. The other purpose of a preflush is to dissolve calcareous materials to minimize calcium fluoride (CaF<sub>2</sub>) precipitation, and to dissolve iron scale or rust to avoid the precipitation of the gelatinous, highly insoluble ferric hydroxide (Fe(OH)<sub>3</sub>). <br><br>Multiple preflush stages using brines such as ammonium chloride (NH<sub>4</sub>Cl) or solvents are used when multiple damage types are present. A preflush is sometimes called a spearhead.
Industry:Oil & gas
A fluid injected into a well as part of a stimulation operation. Fracturing fluids for shale reservoirs usually contain water, proppant, and a small amount of nonaqueous fluids designed to reduce friction pressure while pumping the fluid into the wellbore. These fluids typically include gels, friction reducers, crosslinkers, breakers and surfactants similar to household cosmetics and cleaning products; these additives are selected for their capability to improve the results of the stimulation operation and the productivity of the well.
Industry:Oil & gas
A fluid designed and prepared to resolve a specific wellbore or reservoir condition. Treatment fluids are typically prepared at the wellsite for a wide range of purposes, such as stimulation, isolation or control of reservoir gas or water. Every treatment fluid is intended for specific conditions and should be prepared and used as directed to ensure reliable and predictable performance.
Industry:Oil & gas
A fluid column (usually water or nitrogen) put in the drillstem to provide the desired backpressure at the start of a drillstem test. The cushion usually serves to limit the differential pressure across the test string and packer to avoid flow below the bubblepoint pressure (in which case water is the usual cushion) or to enable a depleted reservoir to flow (nitrogen is the likely cushion).
Industry:Oil & gas
