Testing Equipment and Procedures Suitable to Evaluate Deepwater Scale and Corrossion Inhibitors

With the development in drilling and completion technologies, more and more oils are produced from deeper water depth. This increases the requirement for production chemicals that suitable for application in deep and ultra deepwater fields. To meet the requirements for such production chemicals, comprehensive lab testing need to be carry out including high temperature and low temperature stability, glycol and material compatibility, high pressure rheology and performance testing. Due to the specific deep water conditions such as huge temperature variation (from seabed to reservoir temperature), high shear, great pumping pressure and long residence time, performance testing needs to be carried out after the production chemicals being exposed to such harsh conditions. This requires the use of specifically designed testing equipment to mimic the deepwater field conditions.

In this paper, several scale inhibitors and combined scale inhibitor / corrosion inhibitors were developed to meet the requirement for deep water applications. Following extended stability and compatibility testing, the inhibitors were exposed to the high pressure (4,000psi) flow loop with cyclic temperature variation from seabed temperature to 100 C over a period of 24 hours.  The performance of inhibitors was evaluated after the flow loop exposure. Moreover, rheology profiles at both ambient and high pressure conditions were measured to study the effect of shear rates experienced in deepwater fields. It was found that some products showed poorer performance after going through the flow loop while others maintained similar performance in comparison to the standard samples. The mechanism of this performance difference is discussed in the paper. Based on the full suit laboratory evaluation, one of the products was selected to be used in a deepwater field. The field performance of product is discussed in the paper. Moreover, the selection of a scale squeeze product for the same field is discussed in detail.

This paper aims to highlight the importance of suitable laboratory equipment and testing procedure to evaluate the inhibitors for deepwater applications. The wide range of temperature variations, high shear, long residence time and HT/HP environment for the deepwater fields has been successfully simulated in the laboratory.