Curing Losses: Lab Developments and Best Practices

Abstract

Moderate to severe loss circulation problem encountered while drilling is a major economic burden that increases the total well construction cost dramatically in some cases. This study will focus on best practices to mitigate curing losses in terms of prevention of potential loss by pre-treatment, locating and identifying the losses, identify the mechanism of losses and severity, curing losses strategies and their best drilling practices. In addition, the study will detail typical curing losses materials and their limitations. Finally, selected examples of recent developments in curing losses materials are detailed. The examples are activated nanoparticles dispersed fluid, Epoxy polymer resins, and sodium acid soluble cement solutions. Pre-treatment of loss circulation zone with proper size of bridging materials can reduce and eliminate mud losses into porous formations. The choice of bridging agents will depend on the formation characteristics. The moment of the occurrence (while drilling, circulating or tripping), the severity of the loss (seeping, partial or complete) and the exposed formations are the key factors to identify the best remedy for loss circulation. Losses to reservoir zones are handled differently than non-reservoir zones, wherein only acid soluble or non-damaging material is used in the pay-zone. Seepage losses occur in any formation type when the particle size distribution of the bridging agents is not optimum enough to create an effective seal. This paper describes three different types of novel loss circulation materials to control moderate to severe losses. The paper describes the development of a novel nanoparticle-based chemical treatment composition for its potential use as a loss circulation material. The gelation times were evaluated at different temperatures up to 300°F. The effects of pH and different concentration of activators on gelation times of the new treatment fluid has also been studied. Second example of LCM described in this paper is a novel resin composition comprising an epoxy resin and chemical activator to treat moderate to severe losses. The effect of the chemical activator concentration on the setting time of the resin composition was investigated to accomplish a controlled and delayed polymerization. The third example of LCM described in this paper involves a formulation consisting of an acid soluble cement and a sodium silicate gel that has a high potential to control moderate to severe loss circulation problem. The objective of this acid soluble loss circulation system technology was to design a solution to cure lost circulation in reservoir zones. This is the first study to discuss and detail such topics related to curing losses.