- 行业: Oil & gas
- Number of terms: 8814
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Mathematical techniques that require an algorithm or equation to be repeated until a condition is met. These methods usually require the convergence of a result to a value. Computers are excellent tools for performing iterative techniques quickly and efficiently.
Industry:Oil & gas
Mathematical techniques for summarizing large amounts of multidimensional data into groups. The two most popular techniques are: <ul><li>hierarchical</li><li>k-means. </li></ul><br>The hierarchical system calculates as many clusters as there are data points and displays their relative closeness by means of a dendogram. This system is preferred when there are few data points but the user wishes to see the dendogram to chose an appropriate number of clusters for analysis. Principal Component Analysis (PCA) is a form of hierarchical cluster analysis. <br>The k-means system requires the user to choose the number of cluster to be determined. The computation scatters the centers of the clusters among the data and then moves them until they are "gravitationally bound" to the larger groups of data and no longer move. The points determined in this way represent the central points of the clusters. This technique is very fast and appropriate for very large data sets. It is most commonly used in electrofacies calculations. <br>Cluster analysis is often used to provide electrofacies from wireline data where each curve is set to be a dimension.
Industry:Oil & gas
Mathematical methods that require iterative processing of data rather than applying deterministic equations. Some relationships can be solved only by numerical methods, including most integration problems, some differentials and some statistical processes.
Industry:Oil & gas
Materials, especially rock masses, that formed in their present location and have not been transported. Fault surfaces can separate indigenous rocks from allochthonous rocks, although some allochthonous rocks are clearly delineated by their differing composition.
Industry:Oil & gas
Materials used to provide cathodic protection. Galvanic anodes are made of metals such as zinc, magnesium or aluminum, which corrode more easily than the structure, thus developing enough electric current flow through the electrolyte (such as soils or water). <br><br>Galvanic anodes, also called sacrificial anodes, are commonly used when the current required for cathodic protection is small.
Industry:Oil & gas
Materials typically found in certain types of barium or strontium scales that may be deposited in the wellbore or production tubulars. Any attempt to remove and dispose of NORM materials should be performed according to the legislation and policies associated with such potentially hazardous materials.
Industry:Oil & gas
Materials to provide cathodic protection. Impressed current anodes are relatively inert to corrosion and require an external power source to generate the electric current that will bring cathodic protection to the structure. <br><br>Impressed current systems are used mainly when the current required for cathodic protection is large.
Industry:Oil & gas
Logs that have been calculated from other logs to find the rate at which a log is changing with depth. For example, the derivative caliper (rugosity) calculates the rate at which the caliper is changing from one depth to another. Bad hole conditions that cause the density log to produce incorrect measurements are usually more closely related to the rugosity of the hole than the hole size, so the rugosity curve is the more useful in this regard.
Industry:Oil & gas
Located up the slope of a dipping plane or surface. In a dipping (not flat-lying) hydrocarbon reservoir that contains gas, oil and water, the gas is updip, the gas-oil contact is downdip from the gas, and the oil-water contact is still farther downdip.
Industry:Oil & gas
Located down the slope of a dipping plane or surface. In a dipping (not flat-lying) hydrocarbon reservoir that contains gas, oil and water, the gas is updip, the gas-oil contact is downdip from the gas, and the oil-water contact is still farther downdip.
Industry:Oil & gas
