In the process of directional drilling, the drill pipe screen is an essential filter as a filter device.
Usually, in order to prevent the bottom of the drilling tool or the water hole of the drill bit from clogging, the drill pipe screen can be suspended at the internal thread of the first drill pipe at the bottom of the top drive or Kelly to filter the impurities of the drilling fluid entering the drilling tool, so as to play the role of the last protection.
To a certain extent, it can ensure the safety of drilling tools, reduce the failure probability of downhole instruments in case of plugging, and effectively ensure drilling efficiency. However, most of the existing drill pipe screens are cone-shaped integrated structure, which is not only inconvenient to transport but also difficult to process and high cost.
After partial erosion damage, the whole filter will lose its function, and the damaged part cannot be replaced, resulting in the scrapping of the whole filter. Therefore, it is necessary to deeply analyze the problems existing in the drill pipe screen, and improve the drilling efficiency through process improvement.
Main problems of traditional drill pipe mud screen
In the design of a traditional filter, from the convenience of site users and sufficient flow channel area, it can not be too short or too long, the total length is 0.5 ~ 1.0m, and the lower end of the filter screen is conical.
When drilling fluid enters the drill pipe from the Kelly (or top drive), it first enters the inside of the filter, and then enters the inner hole of the drill pipe through the mesh around the filter. The flow direction of the drilling fluid is forced to change by the filter so that the flow along the inner hole of the drilling tool turns into the outward divergent direction of the outer surface of the filter circumference.
But in fact, when the drill pipe screen is in use, the lower part will be blocked by debris. According to the location of the filter, the main flow hole is just located in the transition zone of the drill pipe.
The bad result is that the original flow direction of the drilling fluid is changed after being filtered by the filter. Under high pressure, the drilling fluid passes through the filter hole at high speed and directly sprays to the transition zone of the drill pipe, which greatly speeds up the erosion damage of the transition zone of the drill pipe.
Application characteristics of new type telescopic drill pipe screen
Design of telescopic drill pipe screen
The telescopic drill pipe screen comprises a first filter section, the upper end of the first filter section is threaded with a support ring, the inner side of the support ring is threaded with an overflow cover with an annular overflow hole, and the annular channel of the overflow cover is used for circulating drilling fluid.
A bailing handle is fixed at the center of the overflow cover. When in use, the supporting ring sits in the drill pipe female buckle under the Kelly protection joint, and its inner side is processed with a shoulder, which is matched with the outer shoulder of the first filter section, and together with the overflow cover plays an axial limiting role on the first filter section.
The utility model also comprises a second filtering section and a third filtering section, the lower end of the first filtering section is provided with an inner shoulder, the upper end of the second filtering section is provided with an outer shoulder, and the second filtering section is connected with the lower end of the first filtering section through a shoulder structure.
The lower end of the second filter section is provided with an inner shoulder, the upper end of the third filter section is provided with an outer shoulder, and the third filter section is connected at the lower end of the second filter section through the shoulder structure.
The bottom of the third filtering section is a closed structure. There are many filter holes with an outer diameter of less than 8 mm on the surface of three filter nodes, and the outer diameter of each filter node is reduced in turn, forming a cone-shaped structure as a whole. The design can adjust the number of filter nodes according to the actual situation.
Characteristic analysis of telescopic drill pipe screen
The telescopic drill pipe screen is installed in the drill pipe female thread under the Kelly protection joint, which can filter the drilling fluid impurities and prevent the water hole blockage of downhole instruments orbits.
The retractable structure design of the three-section filter section makes it easy to carry. At the same time, the split design can realize the separate replacement of each section, which greatly saves the cost.
Each filter section adopts a cylindrical design, which is easy to process.
The utility model has the advantages of simple structure, convenient use, safety, and reliability, and each section can be replaced separately, so as to meet the field use requirements.
In the process of drilling, the mud can be filtered through the flow hole to ensure that the water hole of the bit is not blocked and the bottom hole circulation is unobstructed, which provides a new, economic, and effective technical means for modern drilling technology.
To sum up, in the process of using a traditional drill pipe screen, the bottom hole instrument or drill bit water hole is often blocked. Some filters are eroded and damaged, and the whole filter will lose its function. The damaged part can not be replaced separately, resulting in the overall scrapping of the filter. Moreover, the drill pipe screen has a large volume, inconvenient transportation, complex processing, and high replacement cost.
Due to the retractable characteristics, the volume of the retractable drill pipe screen is greatly reduced, which is conducive to transportation and simple processing. In case of failure, the damaged part can be partially replaced, which greatly reduces the replacement cost, and has a broad application prospect.