How to increase compensation and improve safety and reliability for offshore thermal recovery wellheads？
An offshore oil recovery platform is an offshore working platform built with steel or concrete, or a combination of the two, and is used for offshore oil recovery operations. The structural form of the offshore oil recovery platform varies with the shallow sea or deep sea and the method of offshore oil and gas gathering, transportation, and oil recovery.
Generally, according to their manufacturing materials and characteristics, there are piles of steel or concrete, or a combination of the two, and a hybrid platform.
The offshore oil recovery platform is mainly used for the extraction of oil and gas and the preliminary treatment of oil and gas (such as oil and gas, oil-water separation), and it must become the basis for multiple production wells and oil and gas processing facilities. Therefore, there must be a corresponding deck area and load capacity, but the displacement limit is not as strict as that of a drilling platform.
Due to the long use time of this type of platform fixed at one positioning point, fixed platforms such as jacket platforms or gravity platforms are generally used. In shallow water areas, fixed platforms are also more economical. But in deep water, or in early production, it is more economical to use a mobile platform.
Part of the oil and gas produced by the mining platform can be stored by itself, and a large amount needs to be stored on another oil storage platform, and then the platform is transported to the land through fixed pipelines or shuttle tankers. This is especially necessary when there are several mining platforms in the same area. From a safety standpoint, it is more beneficial to separate the mining platform from the storage platform.
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.
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.
With the continuous expansion of market demand for oil, the exploitation of heavy oil has shifted from land to sea. Offshore thermal wellheads also play an important role in oil development, and their performance and safety have received more and more attention. Existing thermal recovery wellhead devices have relatively small thermal compensation, and onshore thermal recovery wellheads are not equipped with safety valves.
In the process of heavy oil thermal recovery, the casing of oil wells has a large thermal extension, which cannot meet the requirements of offshore thermal recovery technology and safety.
Therefore, Sanjack has developed a safe and reliable offshore thermal recovery wellhead device with large thermal compensation to meet the performance and safety requirements of offshore thermal recovery wellheads.
The offshore thermal recovery wellheads include a valve (1), main bore combination valve (2), manual valve (3), wing combination valve (4), high-temperature pneumatic valve (5), choke valve (6), choke valve ( 7), tubing hanger (8), VIT (9), spacer flange device (10), multiple seals (11), casing (12), high-pressure nitrogen pipeline (13), valve (14), Tubing head (15), upper flange (16), valve (17), valve (18), etc.
Working principle: A wing combination valve is installed on the left side of the main bore combination valve, and a high-temperature-resistant gas-driven valve is installed on the wing combination valve. There are two spacer flange devices under the tubing head. There are multiple sets of seals within the spacer flange device, the left valve of the main bore is connected to the steam injection pipeline, the choke valve is connected to the oil recovery pipeline, and the left valve of the tubing head is connected to the high-pressure nitrogen pipeline. In the process of steam injection and simmering wells, the oil well casing is elongated and deformed under the action of high temperature and high pressure.
The spacer flange device provides elongation space for the extension of the casing. The multiple sets of seals set on the spacer flange device can Effectively seal the elongated part of the oil well casing; during steam injection and simmering well, when the manual valve leaks or blowout occurs during the oil recovery, the pressure in the upper cavity of the piston assembly in the pneumatic valve will be discharged through the reversing valve. The piston assembly drives the valve stem and valve plate to travel upward under the action of the spring to close the valve plate to prevent steam leakage and blowout.
The spacer flange in the design structure developed by Sanjack provides a space for thermal deformation and elongation of the casing, reduces the internal deformation of the casing, and increases the wing combination valve, which can effectively prevent blowout accidents and ensure offshore oil recovery safety.