Residual stresses are self-equilibrating stresses that exist in materials and structures at the absence of instantaneous application of external loadings. In industrial manufacturing and fabrication processes, such stresses can be prominent and may lead to premature failures if uncontrolled. Such failures can be manifested in many forms including stress corrosion cracking, fatigue cracking or brittle facture. This paper is devoted to providing a comprehensive review on residual stress in the manufacturing and fabrication domain with a greater emphasis on welding based residual stresses. Three residual stress evolution mechanisms will be evaluated covering deformation driven stresses during manufacturing, thermally driven during welding and surface modifications such as grinding, carburizing and plating. In welding processes, the residual stresses in the cooling cycle are characterized using Gleeble testing illustrating the stress profiles as a function of temperature. The effect of residual stresses in welded structures will be discussed covering fatigue performance, brittle fracture and effect on Stress Corrosion Cracking resistance. To ensure residual stresses are effectively measured and quantified, a total of nine (9) destructive, semi-destructive and non-destructive residual stress measurement techniques are evaluated. A comparison and evaluation of four (4) common residual stress mitigation techniques are also discussed covering Ultrasonic Impact Treatment, High Frequency Mechanical Impact, shot peening and Post-weld Heat Treatment. The review discussion extends to four (4) factors towards impacting the residual stress magnitude and distribution covering material properties, welding process and clamping and preheating during welding.

The accurate and precise analysis of scale inhibitors plays an important role in making key decisions on the efficiency of scale squeeze and continuous-chemical injection treatments.  At present, several techniques exist for scale inhibitor analysis, but each method has its own limitations and tedious analysis process. In addition, these methods often give results of either total chemical content or elemental analysis without details of chemical speciation.  Especially for phosphonate scale inhibitors, it is well known that there is no analytical methods available on the market to differentiate different species of phosphonate inhibitors, which impedes the applications of different types of phosphonate inhibitors on the scale treatment. There was therefore a need for a next-generation method for phosphonate analysis. An experimental methodology has been developed based upon the use of gold nanoparticles to enhance chemical signatures of scale inhibitors in brines using Surface Enhanced Raman Spectroscopy (SERS).  This methodology enables speciation and measurement at low concentrations in the range of 1 to 100 mg/L (ppm).  This study used two different phosphonate-type scale inhibitors, and initial laboratory results prove that this novel technology can help to differentiate between two different phosphonate-based chemicals. 

Accurate and precise monitoring of corrosion inhibitors in oilfield brine, an important aspect of corrosion control in oil and gas operations, is also a practice recommended by NACE International guidelines. Many operators require residual concentrations of corrosion inhibitors to monitor chemical deliverability at specific locations in a production system.  The residual measurement provides the ability to troubleshoot factors affecting chemical deliverability.  However, residual measurements are notoriously problematic because of the surface-active nature of corrosion inhibitors.  Residual measurement errors can often exceed 100 percent.  Consequently, a need exists for methods that are precise and accurately detect a wider range of corrosion inhibitor molecules.  These methods must also be viable in corrosive oilfield environments where corrosion inhibitors are at low concentrations.  Furthermore, the methods must be portable, enabling field analysis of residual chemicals in collected samples.  Field-based detection methods can reduce the amount of time required to obtain data useful for corrosion control and reduce delays associated in shipping samples to centralized laboratories.