How to remotely and safely monitor the wellhead height and casing elongation in thermal wellheads？
There are a large number of oil wells in the oil field, and the distribution ranges from tens to hundreds of square kilometers, and the distribution is relatively scattered. At present, most of the manual well inspection methods are used, the operation of the equipment is checked regularly and oil production data is recorded every day. This method will inevitably increase the labor intensity of workers, and affect the real-time and even accuracy of equipment monitoring and oil production data. And when the oil pumping unit and electric pump fail, they cannot be found in time, and cannot be effectively monitored, prevented, and controlled.
Heavy oil thermal flooding refers to a more effective method for heavy oil oilfields to increase the temperature of the formation crude oil and reduce the viscosity of the crude oil, thereby increasing the mobility ratio of the formation oil and increasing the oil recovery factor.
Heavy Oil features
- The high content of colloidal asphaltenes and less light fractions. High viscosity and high relative density are the most important characteristics of heavy oil;
- The content of heteroatoms such as sulfur, oxygen and nitrogen is high. For example the sulfur content of heavy oil in the United States, Canada, and Venezuela is as high as 3% to 5%;
- Heavy oil contains more rare metals, such as: Ni, V, Fe, Mo, etc.;
- The paraffin content in heavy oil is generally low, but there are also very few “double high crude oils”;
- In the same heavy oil reservoir, the properties of crude oil are often very different in different sections of the vertical oil layer and between wells on the plane; in the same oil field or oil area, the properties of crude oil are even more different.
- Visco-temperature characteristics of heavy oil (the theoretical basis for thermal recovery of heavy oil);
- Distillation characteristics of heavy oil (one of the mechanisms of steam flooding and fire flooding); when the temperature rises to the bubble point (the lowest temperature when crude oil begins to vaporize), the light components in the crude oil will be separated into the gas phase and recombined. The fraction remains in the liquid phase;
- Thermal cracking characteristics of heavy oil (more prominent in the process of burning oil layers than in the process of steam flooding); thermal cracking of heavy oil means that when the temperature rises to a certain extent, the heavy components in heavy oil will be cracked into coke and light components;
- Thermal expansion characteristics of heavy oil;
According to the driving mode, heavy oil steam injection can be divided into two stages: steam huff and puff and steam flooding, which is a common practice abroad.
Steam huff and puff: The method is simple, and the economic risk is small. Each well can perform 5 to 8 cycles of huff and puff, and the oil recovery rate is as high as 3% to 8%, but the crude oil recovery rate is only 10% to 20%, and a large number of recoverable reserves are lost. The effective heating radius of steam huff and puff is less than 30m. (analog result)
Steam Drive: High technology, high investment, high speed, high energy consumption, whether high profit or high level depends on the advanced reservoir geological conditions and process technology.
Due to the thermal expansion and contraction principle after steam injection during thermal recovery, the technical casing and surface casing in the well will be stretched due to heat and thus need to be monitored. At present, the overall height of the wellhead and the changes of the surface casing are measured manually, which has disadvantages such as poor measurement accuracy, large errors, inconvenient operation, poor real-time performance, and low efficiency.
Therefore, Sanjack adopts remote control technology and communication technology. By installing detection devices, actuators, and PLC automatic control systems at the wellhead position, it can realize the automatic measurement of oil well casing elongation and wellhead height, and the measured data timely is transmitted and stored into the remote industrial computer, which greatly improves the timeliness and accuracy of monitoring, ensures the safety of oil-well gas injection operations, and reduce the labor intensity of workers.
The design consists of the wellhead overall elevation detection mechanism 1, platform 2, the surface casing 3, surface casing detection mechanism 4, thermal recovery gate valve 5, technical casing 6, technical casing detection mechanism 7, tubing head spool 8, thermal production flat gate valve 9, gas control cabinet 10, electric control cabinet 11, remote industrial computer 12 and other components.
Working principle: The upper end of the wellhead overall elevation detection mechanism is connected with the left thermal recovery gate valve, and the lower end is fixedly installed on the platform; the upper end of the surface casing detection mechanism is fixed on the right thermal recovery gate valve, and the lower end is sleeved on the outer surface of the surface casing. One end of the technical casing detection mechanism is installed on the test port of the tubing head spool, and the other end is connected to the gas control cabinet; the PLC in the electric control cabinet can collect and process the data detected by each detection mechanism and transfer it to the remote industrial control computer to display and record, thus it realizes the monitoring of casing elongation and wellhead elevation, which greatly improves the timeliness and accuracy of detection, and ensures the safety of oil well steam injection operations.
The thermal compensation wellhead remote monitoring system designed by Sanjack can realize remote automatic detection of casing elongation and wellhead device elevation to ensure the safety of oil well steam injection operations.