Smaller Coiled Tubing Diameter Achievable by the Use of Lubricants

Abstract

The requirement for well intervention operations in laterals longer than 10,000 ft continues to grow. The current industry trend for servicing long laterals is to increase the coiled tubing (CT) diameter and use fluid hammer or tractor tools. While increasing the CT diameter remains a theoretical option to improve reach, practically, it creates logistical challenges with onshore road transport and offshore crane lifting/ deck loading limitations. Other options such as using fluid hammer and tractor tools may have reasonable operational range, but they have significant limitations by increasing circulating pressures and operational complexity and reducing CT speeds before lock-up. Using lubricants is the simplest, most predictable, and, sometimes, most cost-effective method. However, most current field results show only a 15 to 20% reduction in the coefficient of friction (CoF), from a generic value of 0.24 to 0.20. This CT friction reduction is not sufficient to run CT smaller than 2-in. in long laterals.In this paper, the current status of lubricant usage in well intervention operations is reviewed. Several results of an extensive laboratory program using the first in industry linear friction instrument especially targeting CT operations are also reported. More than 6,600 measurements have been performed to date with many combinations of CT and casing samples and lubricants currently used in field operations. Based on these laboratory results, a new lubricant was developed that results in significantly lower CoFs than previously seen under downhole conditions. The field CoFs with the new lubricant are in the 0.09 to 0.13 range (i.e., field CoF reduction of approximately 46 to 63% from the default value of 0.24) and validate the laboratory results. Numerical simulation results show that CT friction reduction of this magnitude facilitates the CT diameter size decrease in long laterals and brings great benefits to the industry by lowering the operational costs and carbon footprint. Decreasing the CT size is particularly beneficial in Southeast Asia where offshore smaller platforms and smaller CT sizes are vital for intervention operations in small diameter wells.

Improving the Recovery of Hydrocarbons in a Well in the Gullfaks Field by Injecting Sequestrated CO2

“…Although these techniques make it possible to recover hydrocarbons efficiently and profitably, they are very expensive and the scarcity of products to be injected into the wells must be taken into account. Some work in the literature has used a new approach based on enhanced hydrocarbon recovery by injection of sequestrated CO2 to boost production while reducing CO2 emission into the atmosphere [17][18][19][20][21][22][23][24]. The recovery of hydrocarbons from CO2 sequestration is a modern technique still very little used in the oil industry.…”