Recently, with the increasing global energy demand, the development of unconventional resources such as heavy oil, oil sands, and shale gas is also constantly evolving. DTS distributed temperature sensors promote the effective recovery of unconventional resources by monitoring the distribution of underground temperature. The distributed fiber optic temperature measurement system adopts the fiber optic temperature measurement technology of FJINNO, which can adapt to the harsh environment required by oil and gas mining sites, and can operate at effective power. In addition, the DTS system enhances its relationship with customer networks by providing interfaces with production control systems using security protocols and using data formats that are industry standards for oil and gas. To ensure effective mining, it is necessary to monitor changes in pipeline temperature distribution.
Fiber optic temperature measurement for oil wells
Fiber optic distributed temperature sensors (DTS) can measure the temperature distribution along optical fibers with a length of several thousand meters and can be applied to these mining sites. However, conventional products have some problems when used in harsh environmental conditions such as oil and gas extraction sites. Therefore, clients engaged in resource extraction have been seeking fiber optic distributed temperature sensors with excellent environmental resistance as a solution to improve resource extraction efficiency.
In order to meet the needs of customers and solve the inherent problems, a DTS distributed temperature sensor for mining resource extraction sites was developed by applying its professional knowledge of fiber optic measurement technology to process control. DTS measures the temperature distribution along the optical fiber, which is also used as a sensor. For example, a 6-kilometer-long fiber optic can measure the temperature at a one meter interval along the fiber optic, totaling 6000 points. DTS has the following features that are superior to products from other manufacturers: tolerance for harsh environments, small size, light weight, and low power consumption.
Fiber optic temperature measurement system for oil and gas pipelines, distributed fiber optic online temperature monitoring system
Temperature and pressure are very important factors in many underground operations, so for a long time, operators have been using thermal measurement methods to monitor the performance of production wells. In fact, since the last century, engineers have conveniently used wellbore temperature data to calculate flow contribution, evaluate water injection profiles, analyze the effectiveness of fracturing operations, determine the cement top surface outside the casing, and identify interlayer flow. The traditional underground temperature and pressure detection methods have shortcomings in terms of intrinsic safety, explosion-proof performance, strong electromagnetic interference resistance, electrical insulation performance, etc., making it difficult to meet the high requirements of underground operations. FJINNO provides a distributed fiber optic online temperature monitoring system that can continuously monitor temperature within the wellbore range, with high monitoring accuracy, good explosion-proof performance, anti electromagnetic interference performance, and electrical insulation performance, and high reliability. With the advancement of oil extraction technology, the requirements for real-time data collection in the oil extraction process are becoming higher and higher. The commonly used thermocouple temperature measurement is vulnerable, its service life cannot be guaranteed, and its measurement accuracy is limited, which can no longer meet the requirements of underground data collection. Fiber optic temperature measurement has been applied to the measurement of oil reservoir temperature in oil wells to a certain extent.
The fiber optic distributed oil well monitoring system includes temperature measuring optical fibers laid along the wellbore and pressure signal transmission optical fibers; The upper end of the temperature measurement fiber optic cable is connected to the DTS sensor (Raman temperature sensor) located on the well, and the lower and upper ends of the pressure signal transmission fiber optic cable are respectively connected to the fiber optic F-P cavity pressure sensor and modem; The signal output terminals of DTS sensors and modems are connected to the network through communication modules; The system also includes remote monitoring terminals connected to the network and capable of receiving signals from fiber optic temperature sensors.
Distributed fiber optic temperature measurement device
The monitoring terminal includes a display screen for displaying monitoring information and an alarm system for issuing alarm signals.
The distributed fiber optic temperature measurement system for temperature monitoring belongs to continuous distributed measurement, without measurement blind spots, and can achieve a detection distance of more than 10 kilometers at most. Due to the fact that the fiber optic itself is a sensor, it is easy to install, requires less maintenance work, and has high reliability; In addition, due to the characteristics of fiber optic transmission, the intrinsic safety, explosion-proof performance, strong electromagnetic interference resistance, and electrical insulation performance of the entire monitoring system are significantly improved. Distributed fiber optic temperature measurement technology is widely used in temperature measurement and monitoring in hazardous areas, important areas, pressure vessel surface temperature measurement and monitoring, large-scale temperature measurement and monitoring, as well as temperature measurement and monitoring in the transportation field. In the petroleum industry, distributed fiber optic temperature measurement technology can provide real-time and full wellbore temperature detection data, which is suitable for determining the temperature of oil and gas reservoirs, determining the location of liquid and gas production, and detecting pipeline leaks. Meanwhile, fiber optic sensing has the characteristics of electrical insulation, corrosion resistance, electromagnetic interference resistance, and intrinsic safety, making it more suitable for use in oil and gas extraction processes.
According to the different installation positions of optical fibers, distributed optical fiber temperature measurement technology can measure three temperature profiles:
1) Formation temperature: The original formation temperature of an oil and gas reservoir, which is related to the geothermal gradient and thermal conductivity properties of the reservoir.
2) Inflow temperature: The temperature of oil and gas reservoir fluid at the sand surface (before flowing into the wellbore), also known as the sand surface temperature of the oil and gas reservoir. Due to the thermal effects such as viscous dissipation and thermal expansion caused by pressure difference in fluid flow in porous media, the temperature at the point of fluid inflow will be different from the original formation temperature. On the contrary, if there is no fluid flow in the formation, the inflow temperature of the gas reservoir measured by distributed fiber optic temperature measurement in a timely manner will be very close to or equal to the formation temperature of the gas reservoir.
3) Wellbore temperature: the temperature at which fluid flows into the wellbore from the point of inflow and mixes with the wellbore fluid.
The distributed fiber optic temperature measurement device for oil and gas wells is easy to operate, has good stability, high accuracy, complete structure, stable signal source, long service life, and strong resistance to extreme environments, which compensates for the shortcomings of traditional PT100 temperature measurement methods such as cumbersome operation, poor stability, and low accuracy.