- Branża: Oil & gas
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A technique used to minimize the rate of corrosion of a structure. Cathodic protection does not eliminate corrosion, it transfers corrosion from the structure under protection to a known location where artificial anodes (plates or metal bars) are placed and could be replaced easily. Cathodic protection is used for floating vessels, platforms, storage tanks and pipelines <br><br>The cathodic protection principle is based on the electrochemical nature of the corrosion phenomena; the anodic area corrodes (current is discharged) and the cathodic area does not corrode (current is received). Cathodic protection overrides the naturally occurring anodic areas inside a structure, thus turning the structure under protection completely cathodic, which means it receives current from the surrounding electrolyte (for example, soils, water) and does not corrode. Cathodic protection is achieved by passing enough direct current electricity from an external source (a more powerful anode), which could be a galvanic anode or an impressed current anode.
Industry:Oil & gas
A technique used to fire individual perforating guns when multiple guns have been run together in a single trip into the well. Selective firing is used to improve operational efficiency when several intervals are to be perforated.
Industry:Oil & gas
A technique used in squeeze cementing whereby a portion of the slurry is pumped, then pumping stops to expose the slurry to differential pressure against the zone of interest in stages over a period from several minutes to several hours. This pressure, higher than necessary for fluid movement, is applied to force the cement slurry into the area requiring repair. This staged procedure is repeated until all the slurry has been pumped or until no further slurry can be placed into the treatment zone. The cement remaining in the zone forms an effective hydraulic seal with a high compressive strength.
Industry:Oil & gas
A technique used in the assembly of coiled tubing strings at the manufacturing plant. Prior to being formed, the string is assembled from flat steel strips joined by a bias weld that is angled across the strip joint at 45 degrees. When the tubing string is milled, the helical weld form provides enhanced characteristics of the tube at the weld site. These are significantly better than those achievable with the alternative butt weld technique.
Industry:Oil & gas
A technique used in injection treatments, such as matrix stimulation, to ensure a uniform distribution of treatment fluid across the treatment interval. Injected fluids tend to follow the path of least resistance, possibly resulting in the least permeable areas receiving inadequate treatment. By using some means of diversion, the treatment can be focused on the areas requiring the most treatment. To be effective, the diversion effect should be temporary to enable the full productivity of the well to be restored when the treatment is complete. There are two main categories of diversion: chemical diversion and mechanical diversion.
Industry:Oil & gas
A technique used in crosswell seismic and electromagnetic tomography for recording the direct signal from the source or transmitter in one well to the receiver array in another well. This technique is used for mapping the distribution of acoustic velocity and attenuation or electromagnetic resistivity between wells.
Industry:Oil & gas
A technique used for the determination of the electrical properties of a shaly core sample. The sample is flushed with brines of different salinities, and the conductivity determined after each flush. A plot of the conductivity of the sample (C<sub>0</sub>) versus the conductivity of the brine (C<sub>w</sub>) gives the excess conductivity caused by clays and other surface conductors. Then, using a suitable model (Waxman-Smits, dual water, SGS) it is possible to determine the intrinsic formation factor and porosity exponent, and the cation-exchange capacity.
Industry:Oil & gas
A technique used for identifying and measuring the slowness and time of arrival of coherent acoustic energy propagating across an array of receivers. The different packets of coherent energy can then be identified in terms of their origin, for example compressional, shear, Stoneley or other arrivals. In formation evaluation slowness-time coherence is used in conjunction with an array-sonic tool in which the full waveforms at each receiver have been recorded. The technique consists in passing a narrow window across the waveforms and measuring the coherence within the window for a wide range of slownesses and times of arrival.
Industry:Oil & gas
A technique to track the propagation of a hydraulic fracture as it advances through a formation. Microseisms are detected, located, and displayed in time for scientists and engineers to approximate the location and propagation of the hydraulic fracture. Software provides modeling, survey design, microseismic detection and location, uncertainty analysis, data integration, and visualization for interpretation. Computer imagery is used to monitor the activity in 3D space relative to the location of the fracturing treatment. The monitored activities are animated to show progressive fracture growth and the subsurface response to pumping variations. When displayed in real time, the microseismic activity allows one to make changes to the stimulation design to ensure optimal reservoir contact. Also known as microseismic monitoring, this technique delivers information about the effectiveness of the stimulation of a reservoir that can be used to enhance reservoir development in shale gas completions. <br>
Industry:Oil & gas
A technique in which several perforating guns are run on a single trip into the well, and then all are fired simultaneously.
Industry:Oil & gas
