- Branża: Oil & gas
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Fluid in the pore space that does not flow under normal reservoir conditions. This fluid may include water, oil or gas, but most often refers just to bound water. Bound fluid does not flow on primary or secondary production, injection or invasion unless the rock wettability is altered. <br><br>When used in connection with a nuclear magnetic resonance measurement, the term refers to the signal that occurs below a certain cutoff, typically 33 ms in sandstones and 100 ms in carbonates. The source of this signal is bound water, but may also include oil with a viscosity above about 60 cp in sandstones or 30 cp in carbonates. Note that, contrary to the sense of "bound," this oil may or may not be moveable under normal reservoir conditions.
Industry:Oil & gas
Fluid in the pore space that can flow under normal reservoir conditions. This fluid may include water, oil or gas, and will flow on production, injection or invasion. When the term is used in connection with nuclear magnetic resonance measurements, it refers to the signal that occurs above a certain cutoff, typically 33 ms in sandstones and 100 ms in carbonates. The source of this signal is free water and oil with a viscosity below about 60 cp in sandstones, and 30 cp in carbonates. Note that, contrary to the sense of "free," this oil may or may not be residual under normal reservoir conditions.
Industry:Oil & gas
Fluid flow that deviates from Darcy's law, which assumes laminar flow in the formation. Non-Darcy flow is typically observed in high-rate gas wells when the flow converging to the wellbore reaches flow velocities exceeding the Reynolds number for laminar or Darcy flow, and results in turbulent flow. Since most of the turbulent flow takes place near the wellbore in producing formations, the effect of non-Darcy flow is a rate-dependent skin effect.
Industry:Oil & gas
Fluid flow in the borehole from one zone into another in response to pressure differences between the zones. Any time the wellbore pressure rises above the average pressure in any zone, backflow will occur. Analysis of buildup tests involving backflow is either impossible or extremely difficult and usually requires expert input to determine useful information from such tests.
Industry:Oil & gas
Families of the paired pressure change and its derivative computed from a model. The model is usually generated from an analytical solution of the diffusion equation with boundary conditions strategically defined to enable observation of theoretical trends in the pressure-transient response. The boundary conditions that can be defined near the well include constant or variable wellbore storage, limited entry (partial penetration), radial composite (damage skin due to permeability alteration), and a fracture extending the cylindrical wellbore to a extended plane. The borehole trajectory can be vertical, angled, or horizontal. The distant boundary conditions include a sealing or partially sealing planar boundary (fault), intersecting faults and rectangular boundaries (sealing or constant pressure). Further, the diffusion equation can be adjusted to accommodate reservoir heterogeneity in the form of dual porosity or layering. Finally, when generated with computer assistance, the type-curve family can account for superposition in time due to flow-rate variations before and even during the transient data acquisition. <br><br>Originally, type-curve families were printed on specialized (usually log-log) coordinates with dimensionless parameters defining the x and y axes. Today, commercial software can generate the type-curve families on the computer screen, enabling a much more flexible and user-friendly analysis. Further, automated regression (usually least squares) permits an optimized match between the acquired data and a selected model. <br><br>Type curves have greatly enriched the ability of interpreters to extract potential explanations for transient data trends that differ from the radial-flow behavior required for conventional semilog (Horner buildup) analysis.
Industry:Oil & gas
Equipment that transfers heat to the produced gas stream. <br><br>Heaters are especially used when producing natural gas or condensate to avoid the formation of ice and gas hydrates. These solids can plug the wellhead, chokes and flowlines. <br><br>The production of natural gas is usually accompanied by water vapor. As this mixture is produced, it cools down on its way to the surface and also when the mixture passes through a surface production choke. This reduction of fluid temperature can favor the formation of gas hydrates if heaters are not used. <br><br>Heaters may also be used to heat emulsions before further treating procedures or when producing crude oil in cold weather to prevent freezing of oil or formation of paraffin accumulations.
Industry:Oil & gas
Electric detonators used in wireline and electronic firing-head perforating operations, which are immune to radio interference and thus cannot be accidentally triggered by radio transmissions.
Industry:Oil & gas
Equipment or systems used for completion of wells in thermal production of heavy oil.
Industry:Oil & gas
Equipment placed in a pipeline for inserting or retrieving a pipeline scraper (pig).
Industry:Oil & gas
During a nuclear magnetic resonance measurement, the loss of energy by hydrogen atoms in a rock as they align themselves with the static magnetic field. The atoms behave like spinning bar magnets so that when a static magnetic field is applied, they initially precess about the field. Then, through interactions with nuclei and electrons, they lose energy, or relax, and align themselves with the magnetic field. The relaxation of the hydrogen atoms does not occur immediately but grows exponentially with a time constant T<sub>1</sub>. There are two mechanisms for longitudinal relaxation, surface relaxation and bulk relaxation.
Industry:Oil & gas
