Composite Coiled Tubing Research Articles

Thermal response analysis of a medium-deep coaxial borehole heat exchanger by circulating CO2

Geothermal energy is abundant and renewable. It is of great interest to extract geothermal energy efficiently and sustainably. In this paper, a composite coiled tubing (CCT) is put forward and a coaxial borehole heat exchanger (CBHE) technology is utilized to extract heat from the medium-deep geothermal reservoir using phase-change CO2 as the working fluid. CCT has all the advantages of coiled tubing, and thermal insulation could be realized more easily. Considering the transient heat transfer of the formation, a mathematical model of the CBHE system is established and validated by two field tests. Then, both the phase change process of CO2 in the CCT and the long-term heat extraction performance are predicted. Effects of key parameters on the heat output are discussed. It is shown that extracting medium-deep geothermal energy by the phase-change CO2 is realized, and the latent heat of vaporization accounts for a high proportion of the heat carried by production CO2. The larger the mass flow rate is, the more heat could be carried out. But the larger flow rate would lead to the lower temperature of the production CO2 and the more frictional loss. The results provide a reference for exploiting the medium-deep geothermal energy sustainably.

Development and prospect of downhole monitoring and data transmission technology for separated zone water injection

This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China. According to the development stages, the principles, operation processes, adaptability and application status of traditional downhole data acquisition method, cable communications and testing technology, cable-controlled downhole parameter real-time monitoring communication method and downhole wireless communication technology are introduced in detail. Problems and challenges of existing technologies in downhole monitoring and data transmission technology are pointed out. According to the production requirement, the future development direction of the downhole monitoring and data transmission technology for separated zone water injection is proposed. For the large number of wells adopting cable measuring and adjustment technology, the key is to realize the digitalization of downhole plug. For the key monitoring wells, cable-controlled communication technology needs to be improved, and downhole monitoring and data transmission technology based on composite coiled tubing needs to be developed to make the operation more convenient and reliable. For large-scale application in oil fields, downhole wireless communication technology should be developed to realize automation of measurement and adjustment. In line with ground mobile communication network, a digital communication network covering the control center, water distribution station and oil reservoir should be built quickly to provide technical support for the digitization of reservoir development.

Design research and finite element analysis of composite coiled tubing

In this paper, the tensile tests of several types of lay-patterns glass fibre composite material were performed for studying the performance parameters of glass-fibre woven reinforcement epoxy. The comparison of the experimental data and theoretical calculation results demonstrated the validity of directional dependence of the elastic properties of composite material. A type of three-layer composite coiled tubing was designed according to the defect of metal coiled tubing. The main functions of the inner liner include corrosion resistance, abrasion resistance and leakage prevention. The external protection lay can resist abrasion and corrosion. The structural layer can bear the axial pull, pressure and the vibration loads of the tubing body. Lay-patterns of glass fibre of structural layer were designed, and the element models were been established and analysed. The stress states were analysed in terms of different lay-patterns and ply angle, and the composite material CT structure were obtained that can be suitable for drilling conditions. The feasibility and the advantage of composite material CT were validated.

Fatigue life estimate for composite coiled tubing

Based on the research methods for fatigue property and theoretical analysis for fatigue failure of coiled tubing, the decay laws of performance parameters and nonlinear damage cumulating theory of composite materials in the process of loading were introduced into fatigue life analysis of composite material coiled tubing. A fatigue life prediction model suitable for the composite material coiled tubing was established and the fatigue life time calculated. According to analysis of impact of different parameters on fatigue life of composite coiled tubing, methods of improving the fatigue life are presented. The comparative analysis of fatigue life between composite material and metal coiled tubing shows that fatigue life of composite material coiled tubing is higher.

Long-Range Pipeline Monitoring by Distributed Fiber Optic Sensing

Distributed fiber optic sensing presents unique features that have no match in conventional sensing techniques. The ability to measure temperatures and strain at thousands of points along a single fiber is particularly interesting for the monitoring of elongated structures such as pipelines, flow lines, oil wells, and coiled tubing. Sensing systems based on Brillouin and Raman scattering are used, for example, to detect pipeline leakages, to verify pipeline operational parameters and to prevent failure of pipelines installed in landslide areas, to optimize oil production from wells, and to detect hot spots in high-power cables. Recent developments in distributed fiber sensing technology allow the monitoring of 60 km of pipeline from a single instrument and of up to 300 km with the use of optical amplifiers. New application opportunities have demonstrated that the design and production of sensing cables are a critical element for the success of any distributed sensing instrumentation project. Although some telecommunication cables can be effectively used for sensing ordinary temperatures, monitoring high and low temperatures or distributed strain presents unique challenges that require specific cable designs. This contribution presents advances in long-range distributed sensing and in novel sensing cable designs for distributed temperature and strain sensing. This paper also reports a number of significant field application examples of this technology, including leakage detection on brine and gas pipelines, strain monitoring on gas pipelines and combined strain and temperature monitoring on composite flow lines, and composite coiled tubing pipes.

Acoustic emission monitoring using a polarimetric Single Mode optical fibre sensor

Since the hydrocarbon reservoirs in Europe are rapidly depleting, there is a need for new 'intelligent' technology for the efficient commercial exploitation of the remaining hydrocarbon reservoirs: an intelligent and high-temperature, corrosion and fatigue resistant thermoplastic composite coiled tubing. This paper describes the polarimetric Fibre Optic Sensor and accompanying advanced transient signal detection techniques for an early detection of damage in this new type of intelligent composite tubing built for drilling and exploiting hydrocarbon reservoirs. The capabilities of the new optical system for detecting growing damage are demonstrated by carrying out bending tests on short test models of the tube.

The Benefits of Real-Time Downhole Pressure and Tension Data With Wired Composite Tubing

Abstract Continuous composite coiled tubing with embedded electric conductors can provide uninterrupted flow of data from downhole tools. This capability makes monitoring borehole stability throughout the entire drilling process possible, even when conventional mud-pulse telemetry tools are not operating and cannot provide information in real-time. An operator faces many borehole stability problems: stuck pipe, pack-off events, lost circulation, kicks, leak-off tests, and formation integrity tests, all of which can result in periods of non-circulation. However, an operator no longer has to rely solely on surface gauges to provide downhole information to deal with these problems because downhole readings are now available. The benefits of downhole pressure and tension data throughout these problematic and routine activities provide valuable information on events during the most critical operating procedures. Consequently, corrective actions can be taken to prevent or cure borehole stability problems almost as soon as they develop. In addition, downhole data can help reduce drilling time. The borehole is under constant scrutiny. Drilling, tripping, non-circulating, and circulating operations can be optimized while avoiding other potential problems. For example:Swab and surge pressures can be monitored constantly while tripping without circulating;Ledges and tight spots can be identified before they cause severe damage;Time for leak-off tests (LOT) and formation integrity tests (FIT) can be minimized;Early indications of borehole ballooning can be identified before ballooning becomes a major borehole stability issue; and,Hole cleaning intervals can be optimized, reducing drilling time. This paper covers a series of examples where continuous, uninterrupted data transmission was used to anticipate and prevent borehole stability problems and optimize the drilling procedure. Introduction The embedding of copper electrical conductors in Advanced Composite Coil Tubing (ACCT) allows a stream of high speed, high density data to be transmitted in real-time between the downhole components and the surface system. This uninterrupted communication enables the operator to receive all of the data, all of the time, regardless of the operating activities underway. In pipe-conveyed drilling, the real-time application of the "pressure while drilling" (PWD) data has been well documented. It is a very useful tool when used in conjunction with all the other drilling parameters to measure and anticipate drilling problems(1- 3). However, the extent to which mud-pulse telemetry data can be used during all operating activities is limited. The real-time application of PWD data has been hindered because of the constraints placed on the amount of data that can be pulsed to the surface. Ironically, one of the times when PWD data is most useful occurs when it cannot be pulsed up. This could be due to low flow rates or the pumps having to be switched off to avoid damaging the borehole or getting stuck. Surface gauges then have to be relied upon for downhole measurements. With the ability to have "real-time data all the time," pump-off data that could not be seen until the end of the run can now be seen immediately.

Drilling System Combines Composite Coiled Tubing and Hydraulic Workover Unit

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 74538, "The Hybrid Drilling System: Incorporating Composite Coiled Tubing and Hydraulic Workover Technologies Into One Integrated Drilling System," by E. Alan Coats, SPE, and Mark Farabee, SPE, Halliburton Energy Services Inc., originally presented at the 2002 IADC/SPE Drilling Conference, Dallas, 26-28 February.

Mechanical characterization of triaxially braided hybrid composites

AbstractThe use of advanced composites has been expanded to the oil and gas industry. One of the newly developed technologies is in composite coiled tubing that offers the potential of exceeding the performance of metallic tubings. The high strains due to bending and the complex state of stress in these tubes necessitate the better understanding of the correlation between fiber architecture and tube performance. Braided composites can withstand high bending deformation without severe degradation of properties. In this study, braided hybrid composites are presented as an option for achieving high performance coiled tubing under tensile and flexural loads. The effects of material and fabric microstructural parameters on the mechanical behavior of braided hybrid composites are studied. The mechanical characterization of triaxially braided composites has identified the influence of the mechanical properties of the axial yarn, the axial yarn volume fraction, and the braid angle. Overall, this study provides a sound knowledge base for the design, fabrication, and characterization of triaxially braided composites for coiled tubing applications in the petroleum industry.