Active Thermometry Research Articles

Experimental Study of a Temperature Field in a Shut-in Well in Relation to Determining Behind-the-Casing Flow Using Active Thermometry

Abstract —This paper presents results of experimental studies of a thermal field in the barrel of a shut-in (no fluid movement in the casing) well in relation to determining a behind-the-casing upward flow using the method of active thermometry. The studies are carried out using the physical model of a well that is a vertically oriented steel pipe with a system of externally attached copper tubes simulating a behind-the-casing flow. The pipe contains a local heating section, above which a temperature probe is located to record thermal disturbance from the heating section. The effect of free convection in a fluid on the temperature field in the pipe during and after heating is described. It is revealed that there are high-frequency temperature oscillations on sensors that record the temperature of the inner surface (wall) of the pipe and fluid above the heating area, whose value reaches higher than 2 °C and decreases when the distance to the heating region becomes longer. There is an empirical relationship that relates the time of arrival of the temperature disturbance front associated with free convection and the distance to the pipe heating region. Azimuthal temperature distribution curves on the inner wall of the pipe above the heating section are constructed in the absence and presence of a behind-the-casing flow. Qualitative criteria have been obtained indicating the presence of an azimuthally localized behind-the-casing flow (sector flow) of fluid based on the azimuthal temperature distribution analysis.

Diagnostics of the technical condition of wells drilled through freshwater horizons using active thermometry

Relevance. Recently, ESG (Environment, Social, Governance) principles have been given an important role in the agenda of oil and gas companies – this is an actively developing global trend in the modern business environment. One of its key aspects is a responsible attitude to the environment, increasing the priority of solving environmental problems arising from the extraction of hydrocarbons. A significant environmental problem is, in particular, pollution of freshwater horizons during oil production due to their poor-quality insulation during well cementing. At the same time, in the space of the well behind the casing, there is a flow of borehole fluid to freshwater horizons, which has a negative impact on the environmental situation in this region. In this regard, monitoring the technical condition of wells crossing freshwater horizons is an important and urgent task. Object. An operational well drilled through freshwater horizon, in which geophysical studies are carried out by the method of active thermometry – local heating of the casing section is carried out and the dynamics of the temperature field in it is studied. Aim. To identify qualitative patterns and obtain quantitative estimates of the effect of the fluid flow in the space behind the casing (column space) on the temperature field in the casing. Methods. Numerical mathematical modeling of thermal and hydrodynamic processes in a well using the software package Ansys Fluent (ANSYS Academic Research CFD license, agreement with Bashkir State University dated 06/15/2020). Results. The authors have studied the influence of a plane-parallel horizontal fluid flow of the freshwater horizon on the azimuthal temperature distribution of the casing string during induction heating. It is shown that in the case of leakiness of the cement ring in the interval of the freshwater horizon, an inhomogeneity of the azimuthal temperature distribution of the column is observed, reaching a value of few more K. The authors carried out the simulation of induction heating in the well with liquid column flow to the interval of the freshwater horizon. It is shown that the sign indicating the overflow is the occurrence of a temperature disturbance area vertically above the induction heating interval with a length of more than 1 m. In general, the results of the performed studies show the informativeness of the active thermometry method in relation to the diagnosis of the technical condition of wells drilled through freshwater horizons.

ASSESSMENT OF THE POSSIBILITY OF EXPLORING THE WELL'S BACKWATER SPACE BY ACTIVE THERMOMETRY

The use of active thermometry based on local induction heating of the casing string has prospects for solving environmental problems in the study of idle wells. With an inductor power of 1 kW, even with small heating times, it is possible to create and register temperature anomalies in the casing.This article explores the possibility of using active thermometry to solve environmental problems in the study of idle wells.The idea is to measure the temperature of the casing before and after heating by the inductor for a certain time. Obviously, with fixed inductor power and heating time, the change in temperature of the section of the casing string heated by the inductor will depend on the heat exchange between the casing string, the downhole environment and the environment in the annular space. In this case, the conditions of heat exchange with the down hole environment at different depths may remain the same, but with the external environment surrounding the column may change. The reason for this may be a change in the contact of the column with the cement, the properties of the cement, the presence of vertical or horizontal fluid flows behind the well, etc.The paper presents a new analytical solution for calculating unsteady temperature in a metal casing caused by induction heating of a section of the column. The solution is based on a one-dimensional analytical model that takes into account heat exchange between the fluid and the casing, heat generation in the metal column when the inductor is turned on, and heat conduction losses in the cement and rock. To obtain a solution, the Laplace integral time transform method was used.The results of the study show that the amount of heating of the column changes depending on changes in heat exchange conditions and changes in the thermal activity of the environment behind the column. Significant differentiation of temperature along the depth of the well can be caused by a violation of the tightness of the cement ring, the movement of formation water and annular flow. This creates the prerequisites for using the active thermometry method to solve environmental problems in developed oil fields.

Features of the thermal field during fluid injection into the well during induction heating of the casing

Pumping water into productive formations is one of the most common methods of oil field development. The effectiveness of reservoir flooding technology largely depends on the compliance of the design and actual volumes of water injection. Due to the violation of the tightness of the cement ring, fluid flows occur in the column space, which cause non-project withdrawal of the injected liquid into non-perforated layers. Identification and prompt elimination of backwater flows during injection of liquid into injection wells is one of the important tasks of efficient and environmentally friendly development of oil fields. The paper considers the use of induction heating of the casing string to determine the bottom-up backflow when pumping liquid into the well. The research is based on numerical modeling in the Ansys Fluent engineering package. Scenarios of absence and presence of overflow during injection of liquid into the well are simulated. It is shown that in a well without overflow, the temperature field disturbance propagates from the heated section of the column mainly radially into cement and rocks, in a well with overflow, the thermal disturbance from the heating section also propagates vertically in the direction of the overflow, and at a distance of up to 1 m above the heating section, temperature disturbances in the column body and the column space reach 2…3 K. It was found that the signs of overflow are also a decrease in the degree of heating of the casing string and an increased dynamics of cooling of the column over time compared with the absence of the column movement of the liquid. The results obtained serve as a theoretical justification for the fundamental informativeness of the active thermometry method in the diagnosis of backwater flows in injection wells.

THERMAL FIELD IN A HORIZONTAL WELL APPLIED TO THE DETERMINATION OF FLUID FLOW BY ACTIVE THERMOMETRY

Today, in the context of falling oil production and increasing water cut, the importance of geophysical control over field development is increasing. A promising method of production logging is active thermometry, it is based on the creation of a thermal disturbance area in the wellbore, for example, due to induction heating of a section of a metal pipe (liner or casing, depending on the design of the well). As a result of heat exchange with a locally heated pipe section, heat marks are formed in the liquid, moving along the wellbore. The article presents the results of physical modeling of thermal processes during local induction heating of a section of a horizontal well. It has been experimentally established that with an induction heater power of about 1 kW and flow rates in the pipe up to 50 m3/day, the heating of the pipe wall reaches 12 K. As part of the experimental studies, the movement of heat marks was monitored using two modules of temperature sensors distributed over the pipe cross section. It is shown that the nature of temperature change in time is determined by the position of the temperature sensor in the pipe section. The greatest thermal anomalies are noted for sensors pressed against the pipe in its upper part, the smallest - for sensors located in the lower part of the pipe. The fluid flow rate in the pipe was estimated from the rate of passage of the heat mark between the temperature modules. It is shown that the calculated flow rate is overestimated relative to the actual one due to the influence of natural thermal convection, which causes the occurrence of a natural convective fluid flow in addition to the forced movement with a given flow rate. A new analytical solution has been obtained for calculating the dynamics of the pipe temperature in the induction heating section, a comparison of the results of calculations using the analytical model with the experimental results showed good agreement. The results of experimental studies can be used in interpreting the results of field logging wells using active thermometry, in particular, the sensitivity of the pipe temperature in the induction heating section to the flow rate can be used to solve inverse problems of estimating the flow rate in a pipe by measuring its surface temperature using the obtained analytical solution.

EXPERIMENTAL STUDY OF THE THERMAL FIELD IN THE WELLBORE DURING INDUCTION

One of the promising methods of geophysical survey of existing wells is active thermometry. The technology for conducting studies by this method includes artificial heating of a section of a metal casing (for example, induction), registration and analysis of temperature changes in the range of thermal exposure. As a result of heat exchange with the heated section of the column, a thermal disturbance is created in the fluid flow moving inside the column or in the behind-the-casing flow channel. The analysis of non-stationary temperature in the process of induction action allows solving actual practical problems, for example, determining the presence of fluid overflows in the space behind the casing string. The paper presents the results of an experimental study of the temperature field in a well with an artificial heat source in relation to the determination of behind-the-casing fluid flows. The azimuth-localized behind-the-casing flow "from bottom to top" in the well sump to the lower working formation is considered. It is shown that the temperature of the metal string itself, which is recorded by temperature sensors pressed against the string and distributed along the azimuth, provides the most information in terms of detecting behind-the-casing fluid movement, the sensitivity of the temperature of the fluid in the casing string to the presence of overflow is much lower. On the curves of the azimuthal temperature distribution of the column, the sector with overflow is marked by a lower temperature relative to other sectors, which is due to the removal of heat from the column due to the behind-the-casing fluid movement. The results of experimental studies have shown that it is possible to determine the behind-the-casing flow by measuring the temperature field directly in the heating interval, as well as upstream of the heater, and both measurements during heating and after the heater is stopped are informative. It has been established that the magnitude of the temperature anomalies formed due to the flow is about several degrees, in this regard, the results of temperature measurements can be confidently used to determine the intervals of behind-the-casing fluid movement in the well.

The study of heat exchange processes during induction heating of the casing string in relation to the determination of behind-the-casing flows

One of the promising methods of geophysical survey of existing wells is active thermometry. The technology for conducting research using this method includes induction heating of a section of a metal casing string, registration and analysis of temperature changes in the range of induction exposure. As a result of heat exchange with the heated section of the column, a thermal disturbance is created in the fluid flow moving inside the column or in the behind-the-casing flow channel. The analysis of non-stationary temperature in the process of induction action allows solving actual practical problems, for example, determining the presence of fluid overflows in the space behind the casing string. In this work, on the basis of numerical simulation, the features of the formation of a temperature field in the process of inductive heating of the casing string are studied in relation to the determination of behind-the-casing fluid flows. Numerical simulation was performed using the Ansys Fluent software package. Fluid movement in the well is described by the Navier–Stokes equation in the Boussinesq–Oberbeck approximation, and its temperature is calculated taking into account forced and free convection. To calculate the temperature in the inductor, casing string, rocks and cement sheath, a non-stationary heat equation is used. The application of induction heating in diagnosing behind-the-casing flows in the sump, localized below the working perforated formations, in the annular space between the casing string and the cement ring is considered. The distribution curves of the cross-sectional average temperature in the casing string body in the induction heating interval at different flow rates in the casing cross-flow channel are plotted. It is shown that with an increase in the volume flow in the overflow channel, the maximum heating of the column decreases due to more intense heat transfer to the flow in the overflow channel. It has been established that the temperature curves show a “pull” of temperature (temperature disturbances in the body of the casing string propagate in the direction of flow in the overflow channel), the value of which increases with the flow rate in the overflow channel. It is shown that the temperature “pull” (the distance over which the thermal disturbance propagates) during upward flow exceeds the “pull” during downward flow, which is due to the influence of natural thermal convection in the fluid inside the casing string. On the example of the modeling conditions adopted in the work, it was found that up and down flows of more than 0.5 m3/day can be reliably determined from temperature measurements during the induction effect.

A state-of-the-art review of active-thermometry techniques for bridge and pipeline scour monitoring, and exploratory passive thermometry studies

ABSTRACT This paper reviews the application of active thermometry techniques for bridge and pipeline scour monitoring, and explores the potential for passive thermometry through outdoor bucket-type static scour experiments. Active thermometry uses a device to supply heat and then monitors temperature loss. The heat generation is typically through resistive (joule) heating, and temperature is measured using digital temperature sensors, fiber optic temperature sensors, and thermistors. All laboratory studies in the literature were conducted in static conditions, in which the onset and progression of scour are detected by monitoring the changes in thermal properties using sensors placed along the bridge pier (or pipeline). The passive thermometry option explored in this study involved using DS18b20 digital temperature sensors to measure temperature variations in water and in three sediment types: clay, sand, and gravel. The results demonstrated larger diurnal variations in water than in the sediments. Sensors located in the sediment were distinguished from those in water by examining a combination of decrement ratios and phase shifts among the different temperature waveforms obtained for a finite number of diurnal cycles.

Analytical models of induction heating of casing in a producing well

The article is devoted to the study of heat exchange processes in a well during induction heating of metal casing section. Heating of the column leads to an increase in the temperature of the fluid flow in the column. Due to short-term exposure, heat marks appear in the flow. Observation of their evolution forms the basis of active thermometry, a new method in borehole geophysics. Analytical solutions have been obtained for calculating the temperature changes of the upstream and casing during induction heating. Analytical solutions are compared with numerical simulation in Ansys Fluent*. It is shown that the discrepancy between the results of calculations based on analytical and numerical models decreases with an increase in the Reynolds number and the transition to a turbulent flow regime, with active mixing of the flow in the well in it is cross section. The developed models will be used in the planning of geophysical studies in wells by the method of active thermometry. Keywords: active thermometry; borehole; induction heating; column temperature; Nusselt number; Laplace transformations.

Leakage detection of water pipelines based on active thermometry and FBG based quasi-distributed fiber optic temperature sensing

Water pipelines are the efficient and reliable way for water transportation. Leakage of pipelines can lead to tremendous waste of water resources and large economic loss. In this paper, a novel leakage detection method was proposed based on active thermometry and fiber Bragg grating (FBG) based quasi-distributed fiber optic temperature sensing. In this method, the thermal sensing cable was fabricated by coupling heating cable with quasi-distributed temperature sensors. The heat was introduced by the heating cable and the temperature response was measured by the quasi-distributed fiber optic temperature sensor concurrently. The leakage can be detected and located by identifying the local low values in the temperature profile along the pipelines. The feasibility of the proposed method was validated by finite element simulation and experimental investigation. Good agreement between simulation and experimental study was achieved. The results confirmed the effectiveness of the proposed method for leakage detection.

A Review of Ultrasound Thermometry Techniques

Acoustic thermometry is one of non-invasive methods to measure the temperature inside tissue area. Especially, when using the thermal therapy techniques such as High Intensity Focused Ultrasound (HIFU) and other thermal based methods, thermal assessment of heated area seems to be necessary. Some of acoustic properties of medium are temperature dependent; therefore, evaluation of temperature dependent parameters will be an indirect and non-invasive approach in thermometry. In this paper some of thermometry methods based on changes in acoustic properties of medium have been reviewed. The published methods are classified in two main categories: passive and active thermometry. In the passive thermometry, the thermal measurement probes, induced no acoustic signals to the medium, but they receive the radiated signals from the heated medium. In active method, the thermometry probe transmits a signal into the heated region and receives the echoes, then the received RF signals are processed in order to measure the temperature.

A computational model of thermal monitoring at a leakage in pipelines

Monitoring the surrounding pipeline temperature through fiber optic sensors is an efficient method of detecting leakage of fluid such as oil and gas, from pipelines. This article presents a computational model of temperature monitoring in such a leak detection system (LDS). A longitudinal cross section of an idealized pipe-in-pipe flow-line has been simulated, where a localized thermal source is placed on the lower boundary of the computational domain. The heat transfer rates and temperature profiles of the localized heat source have been investigated because a detailed understanding of the excess temperature surrounding a pipeline is essential in designing efficient leak detection systems based on the active thermometry method. The excess temperature profiles from a localized heat source are studied for various physical conditions. More effective results of the rate of heat transfer have been discussed, which are suggestive for controlling leakages in the pipelines. The present investigation would be useful for leak detection systems.

B123 走査型熱顕微鏡による局所温度計測の研究 : 能動温度計測法における加熱方法の最適化(OS-8:マイクロ・ナノ熱工学(2))

B123 走査型熱顕微鏡による局所温度計測の研究 : 能動温度計測法における加熱方法の最適化(OS-8:マイクロ・ナノ熱工学(2))

Application of support vector machine for pattern classification of active thermometry-based pipeline scour monitoring

Pipeline scour monitoring is becoming one of the key requirements in oil and gas industry. To implement scour monitoring for offshore pipeline, a monitoring system that based on active thermometry is proposed. Our previous investigations have shown that the system has provided many advantages over traditional scour monitoring methods. In this paper, a novel scour automatic detection scheme based on nonlinear curve fitting and support vector machine (SVM) is proposed to realize automatic diagnosis of pipeline scour. On account of the varied heat transfer patterns of a line heat source in sediment and water scenarios, the experimental temperature profiles are nonlinearly fitted to their theoretical models. Features extracted by nonlinear curve fitting can dramatically reduce the dimensions of the data. Subsequently, the extracted features are inputted into SVM classifier to judge where the pipeline is exposed to water or buried in the sediment. In order to evaluate the performance of SVM, SVM with different kernel functions are compared with the back-propagation neural networks, which is the most popular neural network for pattern recognition and classification. Results show that the SVM model with radial basis function kernel outperformed other classification models. Finally, aiming to obtain the optimal heating time of the system, the optimal SVM model is employed to recognize datasets with different heating time. Copyright © 2014 John Wiley & Sons, Ltd.

BP neural network recognition algorithm for scour monitoring of subsea pipelines based on active thermometry

Scour monitoring is an important concern for subsea pipeline systems. The active-thermometry-based scour monitoring is based on the difference of heat transfer properties between sediment and sand, recognizes the surrounding media though temperature changing patterns during heating and cooling processes, and hence detects the free spans. Based on the scour monitoring system, a two-layer BP neural network was employed to process the monitoring data and achieved media recognition. The network's inputs were normalized temperature time histories. The network's outputs denoted different media: sediment and water. To validate the method, three experiments were conducted; one was used for training the network and the other two for testing. Also, the effect of noise on the network's performance was studied through simulation. The results demonstrated the feasibility and robustness of the neural network.

20320 SThM用デジタルフィードバック温度計測システムの研究

The Scanning Thermal Microscope (SThM) which can measure temperature in micro - nanoscale has been developed. Quantitative temperature measurement by Active thermometry using analog feedback which makes thermopile output 0 was succeeded. Multifunctional cantilever probe for SThM is fabricated by MEMS techniques. Individual difference of probe affects repeatability in measurement. To provide repeatability, we introduced digital feedback thermometry system which adjusts the gain easily. Our purpose is to develop the flexible system, and we conducted temperature control test. Thermocouple controlled to the target under the periodic heating by the laser. In the measurement of contact conductance, probe temperature was controlled to the constant value even if the contact conductance changes.

G131 走査型熱顕微鏡における能動温度計測に関する研究 : パラメータ自動調整シーケンスの開発

The Scanning Thermal Microscope (SThM) which can measure temperature in micro to nanoscale has been studied. Previously, it was demonstrated that active thermometry with an analog feedback system can measure quantitative temperature. To reduce time and effort for preparation and operation of the SThM, we started to develop a digital system and an auto tuning sequence, which easily adjust feedback parameters for each individual probe and quickly evaluate probe property. The test of the auto-tuning sequence with a chip calorimeter showed a quick calibration of a temperature sensitivity of a thermopile sensor and determination of thermal resistance and heat capacity through a frequency response sequence. The test of the active thermometry operation showed that the system can control probe temperature similar to sample temperature with proper feedback parameters.

Active Thermometry Based DS18B20 Temperature Sensor Network for Offshore Pipeline Scour Monitoring Using K-Means Clustering Algorithm

This work presents an offshore pipeline scour monitoring sensor network system based on active thermometry. The system consists of thermal cables, data acquisition unit, and data processing unit. As the thermal cables emit heats, the distributed DS18B20 digital temperature sensors record temperature information over time. The scour-induced exposure and free spanning can be identified by analyzing the temperature curves. Pipeline exposure and free-spanning experiments were carried out in laboratory, whose results show that the system is able to give overall information about the development of pipeline scour. Difference values analysis reveals the changing patterns of heat transfer behavior for line heat source in sediment and water scenarios. Two features, magnitude and temporal instability, are extracted from temperature curves to better differentiate sediment and water scenarios. Based on these two features, K-means clustering algorithm is adopted for pattern classification of the system, which was implemented in MATLAB and facilitated the automatic detection of the scour monitoring sensor network system. The proposed sensor network has the advantages of low cost, high precision and construction flexiblility, providing a promising approach for offshore pipeline scour monitoring, especially suitable for nearshore environment.

Scour Monitoring System for Subsea Pipeline Based on Active Thermometry: Numerical and Experimental Studies

A scour monitoring system for subsea pipeline based on active thermometry is proposed in this paper. The temperature reading of the proposed system is based on a distributed Brillouin optical fiber sensing technique. A thermal cable acts as the main component of the system, which consists of a heating belt, armored optical fibers and heat-shrinkable tubes which run parallel to the pipeline. The scour-induced free span can be monitored through different heat transfer behaviors of in-water and in-sediment scenarios during heating and cooling processes. Two sets of experiments, including exposing different lengths of the upper surface of the pipeline to water and creating free spans of various lengths, were carried out in laboratory. In both cases, the scour condition was immediately detected by the proposed monitoring system, which confirmed the system is robust and very sensitive. Numerical study of the method was also investigated by using the finite element method (FEM) with ANSYS, resulting in reasonable agreement with the test data. This brand new system provides a promising, low cost, highly precise and flexible approach for scour monitoring of subsea pipelines.

A three-index estimator based on active thermometry and a novel monitoring system of scour under submarine pipelines

A submarine pipeline system is a major asset. Scour monitoring under submarine pipelines is a tough problem and lacks research, especially for nearshore and landfill sections. While these sections are critical for the viability of the pipeline system, they are also the most vulnerable to scour. In this study, a three-index estimator (TIE11Three-index estimator.) based on active thermometry was developed for solving this problem and thereby a novel scour monitoring system was designed for nearshore and landfill sections. Heat dissipates in different ways between in-water and in-sediment scenarios. TIE, consisting of three indices obtained through time history analysis of temperature change during heating and cooling, can well characterize the distinction of heat transfer behaviors between in liquids and solids. By calculating TIE, it is possible to identify whether a location along a pipe is surrounded by water or soil. Considering this, the system utilizes a thermal cable to generate heat with a heating belt and concurrently measure temperature with DS18B20s. The thermal cable was deployed parallel to the pipeline. Analyzing the acquired data by TIE, identification of free spans is achieved. Several experimental tests were conducted using the system. Results confirm the methodology and substantiate the scour monitoring system.