Corrosion Control Saves Money Throughout the Life of a Well
Noninvasively quantitatively scan the interior surface and determine the thickness of production casing in liquid or gas environments and at up to 90° deviation.
Measure internal and external casing corrosion with full azimuthal coverage.
Measure and monitor the inner wall of casing and tubing strings with accurate radial measurements from the Multifinger Caliper Tool (PMIT).
Detect metal loss and changes in casing geometry, regardless of casing fluid type.
The PAL pipe analysis log is a corrosion-monitoring service primarily for detecting small holes and defects.
Pinpoint electrochemical corrosion problems, present and future.
The PS Platform Multifinger Imaging Tool (PMIT) is a multifingered caliper tool that makes highly accurate radial measurements of the internal diameter of tubing and casing strings.
Why evaluate corrosion?
It has been estimated that 1% of the total operating costs of the petroleum industry could be saved by the correct application of existing corrosion protection technology. Wireline corrosion evaluation services can be used to save money throughout the life of a well. Corrosion control is particularly cost effective for deep or remote wells, wells expected to have a long lifetime, or wells producing CO2 or H2S.
When problem areas are predicted, prevention budgets may be spent wisely. It is worthwhile to monitor for weak points because corrosion or damage prevention is less costly than repair. And precise identification of failure can be used to minimize repair expense.
What causes corrosion?
Electrochemical corrosion can occur when a metal is immersed in a conductive medium. Galvanic or bimetallic corrosion occurs when two metals in contact are immersed in the same fluid (the most obvious example is a battery in which the two metals are very different). Slight differences between casing joints, defects and impurities can also trigger galvanic action. Concentration cell corrosion occurs when the same metal is immersed in a fluid that varies in composition from one point to another. The change in composition may be due to differences in pH or the concentrations of dissolved gas (e.g., oxygen) or dissolved salts. Galvanic and concentration cells exist on scales ranging from kilometers to millimeters or smaller. Other corrosion processes that can cause problems downhole are stress corrosion, hydrogen embrittlement, and chemical corrosion.
In addition, noncorrosive metal loss can be caused by abrasion from produced fluids and solids or by mechanical wear. The nature of corrosive attack can be relatively uniform, as in general corrosion, or highly localized, as in pitting, where penetration can be very rapid.
Hydrogen sulfide, carbon dioxide, and oxygen and chloride ions are known to promote corrosion, though the mechanisms by which they act are very different. The effects of corrosion can be reduced (and in some cases eliminated) by using resistant metals or inert protective coatings, or by introducing chemical inhibitors into the fluid. Corrosion can be controlled with electrochemical means by applying cathodic protection through the placement of sacrificial anodes, but more commonly a DC current is impressed on the casing from a rectifier and groundbed.
Corrosion monitoring
Downhole corrosion problems are many and varied, requiring many techniques for their detection and monitoring. We provide a combination of measurements—acoustic, electrical, and mechanical—so you can make the right choice to get the answers you need:
- inside diameter
- casing thickness
- scale detection
- pipe sections
- hole detection
- metal loss indicators
- mechanical wear
- corrosion rate
- condition of multiple strings
- string composition
- effectiveness monitoring of anticorrosion systems.
Related products and services
Request More Information
|