This paper describes the design criteria and operational experience with a new, second-generation Rotary Closed Loop System (RCLS). Rotary Closed Loop Systems are clearly revolutionizing the way in which oil & gas wells are drilled. During the past 5 years the technology has emerged from prototype status to a standard application in locations with good infrastructures such as the North Sea and the Gulf of Mexico. In remote areas with more challenging logistics such as West Africa, Asia Pacific, and South America, the use of rotary steerable technology has been very limited. Based on the accumulated experience with a leading system, a new generation of Rotary Closed Loop System has been introduced specifically for remote operating areas. These areas have a relatively poor infrastructure, difficult logistics and some experience extreme environments. The paper describes the technological challenges that had to be overcome for the standard application of Rotary Closed Loop Systems in remote areas and illustrates the advantages to the oil & gas industry with some exemplary case histories. Introduction Rotary Closed Loop System (RCLS) drilling technology was first introduced to the North Sea in early 1997. The technology was ground breaking at that time without any significant parallels. It has been as revolutionary to the drilling industry as the introduction of Measurement While Drilling (MWD) or Steerable Motor technology was in the late 1970's and mid 1980's. The complexity of these new systems has been a significant challenge when it came to their wide spread use. In areas with short supply chains and good infrastructure like the North Sea, the new technology has widely replaced conventional directional drilling technology. It has become the standard drilling system for many fields in the 12. 1/4 inch to 8. 1/2 inch hole sections. To continue the expansion of the use of this technology, new system requirements were defined. These new system requirements are aimed at helping the industry explore and develop oil & gas resources more economically throughout the world, including the most remote areas. Design Criteria for the New Generation Rotary Closed Loop System The first generation RCLS has successfully replaced conventional directional drilling methods (such as steerable motor and MWD/LWD systems) in many fields. However, this has primarily been limited to high cost offshore operating areas with high activity and good infrastructure. This is a result of the fact that demand has continued to rapidly grow with new systems being added to the operating areas having an established infrastructure. As operators gained confidence in the technology, the demand spread to all areas of the world where high operating costs drive the need for developing oil & gas reserves more economically. A continuation of the high growth rate for RCLS applications is therefore still expected. Experience in the maintenance of the 1st generation product, in its field application, and in the build up of the supporting infrastructure to maintain and operate the system, led to a requirement for a new RCLS generation. Step change in reliability The first generation system has reached a reliability level comparable to the conventional directional drilling technology with steerable motors in combination with Measurement While Drilling / Logging While Drilling technology. The data shows that the reliability rapidly improved in the first two years of commercial application, Fig. 2. For the years 2000 and 2001, the reliability of the system has stabilized at a level of 75 to 80 % for the probability of successful runs. This trend indicates that no further significant increases are to be expected without major changes to the existing system. This has led to the first major design criteria for a new generation system - to achieve a step change in reliability. Step change in reliability The first generation system has reached a reliability level comparable to the conventional directional drilling technology with steerable motors in combination with Measurement While Drilling / Logging While Drilling technology. The data shows that the reliability rapidly improved in the first two years of commercial application, Fig. 2. For the years 2000 and 2001, the reliability of the system has stabilized at a level of 75 to 80 % for the probability of successful runs. This trend indicates that no further significant increases are to be expected without major changes to the existing system. This has led to the first major design criteria for a new generation system - to achieve a step change in reliability.
This paper reviews the operational experience gained of utilizing Rotary Closed – Loop Steerable (RCLS) drilling technology on development drilling projects in the UKCS for the period 1997 – 2000. Despite the general decline in drilling activity in this period, there was a significant increase in RCLS drilling activity. Sufficient operational experience has now been gained to a) fully evaluate the impact of the new technology on the drilling operation and to b) make a comparison of RCLS system performance against a conventional drilling operation. The paper focuses on the following three key performance measures of the RCLS operation:Reliability of the Technology: A review is made of the RCLS system performance, where problems occurred at the introduction of the technology and what solutions were implemented to improve system reliability.Operational Performance: An assessment of the factors which influence the operational efficiency of the RCLS operation is presented and a comparison is made with the operational efficiency of a conventional drilling operation.Safety – Environmental Performance: The introduction of RCLS technology facilitates a safer working environment for drilling operations at the rig site. The positive impact that the technology has made to the drilling operation is reviewed here. In reviewing past performance, the direct and indirect advantages of deploying RCLS are discussed in light of experience gained on a number of offshore UK North Sea assets including those projects managed by low cost operators or where field economics are marginal. Introduction Rotary Closed – Loop Steerable (RCLS) drilling technology was introduced to the UK sector of the North Sea in May 1997. This technology was originally developed in conjunction with ENIAgip in Italy for potential use on ERD type wells. Initially, the technology was limited to the 6 3/4" tool size to drill hole sizes in the range 8 3/8" to 9 1/2". Eighteen months later the 8 1/4" tool was introduced to drill hole sizes in the range 12 1/4" to 14 3/4". Since that time, the system has drilled 800,000ft which represents approximately 78% of the total rotary steerable footage drilled in North Sea UK sector. In view of the general downturn in drilling activity in the period 1999 – 2000, the growth trend in RCLS activity is significant. There were two main drivers which facilitated this growth in RCLS activity in the UK and North Sea, namely 1) the industry's need to reduce operating costs and 2) the technical limitations with conventional steerable drilling techniques. The degree to which RCLS technology could provide a satisfactory solution to these two areas would depend on the operational performance of the system (directional performance, dogleg capability, real – time data acquisition and system reliability). The next section provides a review of the RCLS operations in the UK sector of the North Sea. RCLS Operations Review Figure 1 shows the growth in RCLS activity relative to the overall drilling activity during the period 1997 – 2000, with expected activity to end of 2001. In the last three years the RCLS activity has shown 50% or better growth. Initially, the focus for utilising rotary steerable drilling technology was in situations where directional operations were considered inefficient with conventional steerable drilling methods, and therefore the emphasis was on cost reduction. Specifically, RCLS was deployed in situations where oriented or slide drilling proved difficult or frequent trips for bit and BHA changes were required.
Building on the application's success in larger diameter holes, rotary steerable drilling is becoming an established drilling method in 6" hole sections. Rotary drilling in these smaller hole sizes does, however, bring with it some concerns. These include the requirement for high surface rotary speeds to achieve acceptable penetration rates. As a result, these rotary systems may need to place very high dynamic loads on small diameter drillpipe. A new rotary steerable system has been developed which integrates a high performance drilling motor into the bottom hole assembly. By driving the drill bit with the downhole motor, drillpipe rotary speeds and weight on bit can be reduced while simultaneously increasing rate of penetration. This reduces the stress on the drill string and increases drilling performance. This paper describes this new system illustrated with results from real wells. Introduction The mutual objective of oil companies and "drilling and evaluation" service companies is to deliver the most cost effective well, positioned optimally in the reservoir, and capturing high quality formation evaluation data while drilling.Over the last decade there has been significant service company technology investment driven by this objective. One of the key technologies developed has been rotary steerable systems. Rotary steerable systems were introduced to the drilling industry in the mid 90s. The drilling industry was quick to recognize the value delivered by this technology as observed by the rapid rise in the use of the technology over the last decade. Today it is estimated that 20% of all directional footage is made using rotary steerable technology. The initial systems were developed for 8 ½" hole size as these sections possessed the need for accurate well placement and steerability in the oil or gas bearing reservoir. Once the the concept and technology was proven, the industry embraced the idea of using the same technology to drill the well to the reservoir and larger hole size were developed. Within 5 years, rotary steerable systems were available on the market that could drill hole size from 18 1/8" to 8 3/8". The most recent development of rotary steerable systems has been for hole size smaller than 8 1/2" and there are now several systems available to drill +/- 6" hole. Although, in many applications, the use of rotary steerable systems adds significant value, the need for systems to be 100% rotary driven from surface have added drillstring wear and downhole dynamic dysfunctions that can negate the benefits in certain applications. The remainder of this paper will discuss these issues in detail and demonstrate how these issues have been addressed through improved understanding and associated technology development.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.