The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
Alexandre Lavrov - One of the best experts on this subject based on the ideXlab platform.
-
effect of eccentric annulus washouts and breakouts on well cementing quality laminar regime
Energy Procedia, 2016Co-Authors: Alexandre LavrovAbstract:Abstract Annular cementing is an essential step in well construction in underground CO 2 storage projects. The quality of cementing depends on the quality of mud displacement by the fluids injected into the annulus during the cementing job. An engineering numerical model of annular fluid displacement in a vertical well was used in this study to investigate the effect of well profile on the displacement quality. Annular displacement of the thinner fluid in place by the injected thicker fluid was modelled. The effect of the following factors on the displacement was studied: slightly irregular shape of the well cross-section; eccentric positioning of the Casing in a circular well; a local washout (enlargement of the well cross-section); throughgoing breakouts. Random irregularities of the well cross-section were found to have only a minor effect on the advancement of the displacement front and on the injection pressure. Eccentric positioning of the Casing Pipe was found to cause flow channelization due to the yield-stress rheology of the fluids. The eccentricity was found to affect the injection pressure as well. An isolated washout was found to have only a minor influence on the injection pressure and the displacement front propagation. Borehole breakouts were found to cause severe channelization of the injected fluid, and a substantial reduction in the injection pressure. Continuous enlargements of the annulus caused e.g. by borehole breakouts or eccentric positioning of the Casing were thus shown to have a more detrimental effect on the annular displacement than a local, isolated enlargement caused e.g. by a washout. Abnormally low injection pressure during a cementing job might serve as an indication of flow channelization through such a throughgoing enlargement.
Genda Che - One of the best experts on this subject based on the ideXlab platform.
-
Casing Pipe damage detection with optical fiber sensors a case study in oil well constructions
Advances in Civil Engineering, 2010Co-Authors: Zhi Zhou, Minghua Huang, Genda CheAbstract:Casing Pipes in oil well constructions may suddenly buckle inward as their inside and outside hydrostatic pressure difference increases. For the safety of construction workers and the steady development of oil industries, it is critically important to measure the stress state of a Casing Pipe. This study develops a rugged, real-time monitoring, and warning system that combines the distributed Brillouin Scattering Time Domain Reflectometry (BOTDR) and the discrete fiber Bragg grating (FBG) measurement. The BOTDR optical fiber sensors were embedded with no optical fiber splice joints in a fiber-reinforced polymer (FRP) rebar and the FBG sensors were wrapped in epoxy resins and glass clothes, both installed during the segmental construction of Casing Pipes. In situ tests indicate that the proposed sensing system and installation technique can survive the downhole driving process of Casing Pipes, withstand a harsh service environment, and remain intact with the Casing Pipes for compatible strain measurements. The relative error of the measured strains between the distributed and discrete sensors is less than 12%. The FBG sensors successfully measured the maximum horizontal principal stress with a relative error of 6.7% in comparison with a cross multipole array acoustic instrument.
Forsaeus Nilsso Stefa - One of the best experts on this subject based on the ideXlab platform.
-
Durability of District Heating Pipes
2002Co-Authors: Forsaeus Nilsso StefaAbstract:This thesis is focused on mechanical loads and moisture related problems with a potential to critically harm the functionality of pre-insulated district heating Pipes and Pipe joints. Directly buried Pipeline bends are investigated with respect to limiting deformations from a thermally induced lateral displacement. A new approach is introduced; stating that very large deformations of the insulation foam are tolerable as long as overheating of the Casing Pipe is avoided. A local increase in heat losses and loss of axial shear stiffness is not critical, but a too high temperature will accelerate the rate of deterioration of the polyethylene material. Measurements indicate that the earth pressures required to reach critical deformations are not likely to develop in regularly compacted backfill materials. Problems related to backfilling with reused excavated soil containing coarse-grained materials are of particular interest. The lifetime implications from large stones causing deep indentations in the Casing Pipe wall are studied. A conceptual framework for the force interaction between a laterally displaced Pipe and a stone adjacent to it is presented, along with tests on the long-term strength of severely strained polyethylene. The risk for obtaining deep indentations depends on the compaction of the backfill, and is greatest in materials compacted to "ordinary" levels. There is an obvious temperature dependence in the expected lifetime. To avoid the combination of indentations and an elevated Casing Pipe temperature, compaction of backfill material containing large stones should be avoided around Pipeline bends. The strength of Pipe joints to axial movements through coarse-grained backfill material is studied experimentally. It is concluded that electro-fusion welded sleeves are superior to other types. But with a simple external protection, consisting of a polyethylene net, the much cheaper single-sealed non-shrinking sleeve can be used in very tough backfill materials. The consequences of a leaking joint seal are investigated experimentally and analytically. Homogeneous and defect-free PUR foam will act as a moisture barrier, protecting the medium Pipe from water. Air-gaps or voids in the foam may promote an inflow of groundwater by a "breathing effect" caused by temperature variations. Hence in order to improve the performance of the joints, efforts should be made to develop the methods for foam injection to ensure a complete filling of the joint space. Vapour diffusion in plastics Pipes heating systems and in cooling systems is studied analytically. In heating systems with polyethylene medium Pipes, vapour will diffuse outward and possibly condensate and accumulate in the colder parts of the insulation foam. Calculations indicate that the increase in heat losses during the first 50 years of service is about 25 - 30 %. In cooling Pipes, vapour passing in from saturated soil will condense in the colder insulation. Simplified calculations show that condensation of water starts almost immediately
B. Adl-zarrabi - One of the best experts on this subject based on the ideXlab platform.
-
Development of a Non-destructive Testing Method for Assessing Thermal Status of District Heating Pipes
Journal of Nondestructive Evaluation, 2020Co-Authors: H. P. Lidén, B. Adl-zarrabiAbstract:Pre-insulated district heating (DH) Pipes have been in use for more than 40 years. The thermal performance of these Pipes decreases over time as a result of thermal and mechanical aging, which leads to higher heat energy losses. A non-destructive method based on a cooling method is under development for assessing the thermal performance of a DH network. The method utilizes the copper wire, which is already embedded in the polyurethane insulation for detection of water leakage, as a sensor for measuring the temperature at the position of the copper wire. The method involves a shutdown of a selected part of a network for less than 2 h and evaluating the cooling process by measuring the supply Pipe temperature and the temperature of the copper wire. The method was applied in a DH network during heating season. The thermal conductivity calculated by the method [0.027 W/(m K)] was in good agreement with the reference value [0.026 W/(m K)]. The cooling of the network can be measured at a valve or at other more easily accessible steel parts. It was also shown that the method is applicable for DH networks without a copper wire. However, a temperature measurement is needed on the Casing Pipe.
Zhi Zhou - One of the best experts on this subject based on the ideXlab platform.
-
Casing Pipe damage detection with optical fiber sensors a case study in oil well constructions
Advances in Civil Engineering, 2010Co-Authors: Zhi Zhou, Minghua Huang, Genda CheAbstract:Casing Pipes in oil well constructions may suddenly buckle inward as their inside and outside hydrostatic pressure difference increases. For the safety of construction workers and the steady development of oil industries, it is critically important to measure the stress state of a Casing Pipe. This study develops a rugged, real-time monitoring, and warning system that combines the distributed Brillouin Scattering Time Domain Reflectometry (BOTDR) and the discrete fiber Bragg grating (FBG) measurement. The BOTDR optical fiber sensors were embedded with no optical fiber splice joints in a fiber-reinforced polymer (FRP) rebar and the FBG sensors were wrapped in epoxy resins and glass clothes, both installed during the segmental construction of Casing Pipes. In situ tests indicate that the proposed sensing system and installation technique can survive the downhole driving process of Casing Pipes, withstand a harsh service environment, and remain intact with the Casing Pipes for compatible strain measurements. The relative error of the measured strains between the distributed and discrete sensors is less than 12%. The FBG sensors successfully measured the maximum horizontal principal stress with a relative error of 6.7% in comparison with a cross multipole array acoustic instrument.