CN101864924A - Drilling fixed-point plugging method - Google Patents

Abstract

The invention relates to a fixed-point plugging method for drilling. The upper joint of the plugging device of the fixed-point plugging device for drilling is connected to a drill string, and the upper part of the drill string is connected to a faucet. The water tap and the mud pump are connected through a hose; After the fixed-point plugging device is lowered to the leakage point on the well wall, the mud pump is turned on, and the mud pump injects liquid from the inside of the drill pipe. Under the mud pressure, the plugging steel ball seals the sliding sleeve inside and moves downward. Under the action, the center sliding rod moves downward, opens the lower sealing baffle, and stops when the sliding sleeve moves to the position of the limit retaining ring, and the mud squeezes the plugging material into the formation through the radial through hole and the vertical through hole to realize fixed point The purpose of plugging and extruding the plugging material into the formation. The beneficial effect of the present invention is that: the plugging of the present invention has strong pertinence, can satisfy conventional plugging, and can regularly transport the expansive plugging material to the part of the lost formation, thereby improving the compressive capacity of the expansive plugging material to seal the formation .

Description

Drilling fixed-point plugging method

technical field

The invention relates to a method for fixed-point leakage plugging in well drilling.

Background technique

Lost circulation is a common and often encountered complex problem in petroleum engineering. Due to the complex downhole caused by lost circulation, it is extremely harmful to drilling and completion construction, and lost circulation has always been a concern of petroleum engineering circles at home and abroad. In the drilling operation, once leakage occurs, not only the drilling time will be delayed, the drilling fluid will be lost, and the oil and gas layers will be damaged, but it may also cause a series of complex situations and accidents such as well collapse, stuck pipe, blowout, etc. due to the instability of the well wall, and even lead to the failure of the wellbore. scrapped, resulting in major economic losses.

During the drilling process, due to the complex formation, the formation pressure coefficient changes greatly, and it is difficult to determine the location of the leakage layer. The interval where the leakage occurs is often not at the bottom of the borehole, and even with the continuous deepening of the drilling operation, the previously blocked formations often have repeated leakage. If the traditional plugging method is adopted, the plugging material is often packed into all the wellbore space below the leakage point, which will cause a great waste of plugging material, prolong the operation time and increase the cost of plugging. In addition, with the development of plugging technology, great changes have taken place in plugging materials. There are many materials with high water expansion rate, such as gel polymer, which are used in formation plugging. However, it is difficult to control the swelling speed of these materials when encountering water. Sometimes the lost circulation plugging material has already absorbed water and swelled before entering the predetermined formation. When the predetermined formation is reached, the volume of the expanded gel is already greater than the volume of fractures, pores and caves and cannot enter the formation. Even if the gap is squeezed into the formation, the plugging material has lost the space for further expansion, and its plugging strength has seriously decreased, basically losing the purpose of plugging.

Contents of the invention

The problem to be solved by the present invention is to propose a fixed-point plugging method for drilling in view of the above-mentioned prior art, which has high plugging strength, greatly improves economic efficiency, and is easy to operate.

The solution adopted by the present invention for solving the above-mentioned problems is: a method for fixed-point plugging of well drilling, which is characterized in that it includes the following steps:

1) Calculate the volume of the plugging material that needs to be squeezed into the lost space on the well wall according to the size L of the lost space on the well wall;

2) Calculate and connect the plugging casing volume, casing length and center sliding rod length according to the volume of the plugging material;

3) Put the plugging material into the space between the casing and the center sliding rod, and assemble the device for drilling fixed-point plugging;

4) Calculate the distance from the lower part of the drilling fixed-point plugging device to the wellhead according to the position of the leakage point on the well wall, connect the upper joint of the plugging device of the drilling fixed-point plugging device to the drill string, and connect the upper part of the drill string to the faucet. Mud pumps are connected by hoses;

5) After the fixed-point plugging device for drilling is lowered to the leakage point on the well wall, the mud pump is turned on, and the mud pump injects liquid from the inside of the drill pipe. Under the mud pressure, the plugging steel ball seals the internal sliding sleeve and moves downward. Under the thrust of the sliding sleeve, the center sliding rod moves downward to open the lower sealing baffle, and stops when the sliding sleeve moves to the position of the limit retaining ring, and the mud squeezes the plugging material in through the radial and vertical through holes. Formation, to achieve the purpose of fixed-point plugging and squeeze the plugging material into the formation, and then lift the drill string and the device for fixed-point plugging out of the wellhead to complete the plugging operation.

The invention is based on the fact that in the oil drilling process, the well depth and the formation are complex, and the formation often leaks, causing huge economic losses. The oil drilling formation is complex, and the loss point is often not at the bottom of the well. Sometimes after the plugging is completed, as the drilling depth increases, the original plugged formation or the position in the well will re-occur. In the present invention, the plugging material is installed in a special plugging tool, the special plugging tool is transported to the lost stratum by a drill pipe, the liquid is injected from the inside of the drill pipe by a high-pressure mud pump, and the plugging steel ball is used under mud pressure. The inner sliding sleeve is sealed, so that the sliding sleeve moves downward, and under the thrust of the sliding sleeve, the sliding rod moves downward to open the lower sealing baffle. When the sliding sleeve moves to the position of the limit retaining ring, it stops, and the mud squeezes the plugging material into the formation through the radial and vertical through holes to achieve the purpose of fixed-point plugging.

The beneficial effects of the present invention are:

The plugging of the present invention has strong pertinence, not only can satisfy the conventional plugging, but also can regularly transport the expansive plugging material to the lost stratum, which slows down the expansion of the expansive plugging material in the transportation process and improves the efficiency of the expansive plugging material. Compressive capacity of the sealed formation. In addition, this plugging method can implement fixed-point plugging for the leakage in the middle of the well section, which changes the previous method of filling the entire wellbore with plugging materials. It not only saves costs, has a good plugging effect, is economical and efficient, but also is easy to operate and easy to use .

Description of drawings

Fig. 1 is the device structural representation of fixed-point plugging of drilling of the present invention;

Fig. 2 is a schematic diagram of the structure of A-A in Fig. 1;

Fig. 3 is the B-B direction structural schematic diagram of Fig. 1;

Fig. 4 is a schematic diagram of the structure along the direction C-C of Fig. 1 .

In the figure, 1-drill string; 2-upper joint of plugging device; 3-plugging steel ball; 4-support ring; 5-sealing ring; 6-pin; 7-central sliding sleeve; 8-screw plug; 9 -outer tube through hole; 10-limit retaining ring, 11-center sliding rod; 12-sleeve; 13-lower sealing baffle; 14-collar; 15-sliding sleeve through hole; 16-radial through hole; 17 - Vertical through holes.

Detailed ways

The present invention will be further described in detail through the embodiments below in conjunction with the accompanying drawings, but the embodiments will not constitute a limitation to the present invention.

After the assembly of the fixed-point plugging device for drilling, it is a technical short connection, wherein the upper joint 2 of the plugging device is the main body of the short connection, and the outer tube through hole 9 is radially processed on the lower part of the body (the three outer tube through holes are in the horizontal plane. 120 ° distribution), vertical through holes 17 and radial through holes 16 (3 radial through holes 16 are distributed at 120 ° in the horizontal plane), radial through holes 16 and vertical through holes 17 are connected, in order to facilitate processing and Ensure that the radial through hole 16 is connected with the vertical through hole 17, and the outside of the radial through hole 16 is sealed by the plug 8;

The limit retaining ring 10 is installed at the inner lower end of the upper joint 2 of the leak-stopping device, and the limit retaining ring 10 and the upper joint 2 of the leak-stopping device are connected in a threaded manner, and the inner hole of the limit retaining ring and the center sliding rod 11 are slidable. way to connect;

The inner upper end of the joint 2 of the plugging device is provided with a central sliding sleeve 7, and the plugging steel ball 3 is installed on its top, and the collar 14 is installed on the top of the support ring 4, and is connected with the joint 2 of the plugging device by threads.

An inner shoulder is processed on the upper part of the inner diameter of the joint 2 on the plugging device, and a support ring 4 and a sealing ring 5 are installed on the inner shoulder; three holes are processed in the radial direction of the position of the A-A section of the joint on the plugging device. The small hole is used to install the pin 6 and is used to fix the center sliding sleeve;

The lower part of the central sliding sleeve is processed with a sliding sleeve through hole 15, and the lower part of the central sliding sleeve is connected to the central sliding rod 11, and the lower part of the central sliding rod is threadedly connected to the baffle plate 13, and the casing 12 connected to the lower end of the upper joint 2 of the baffle plate and the plugging device is plugged in. way to connect.

The working principle of the fixed-point plugging operation of the present invention will be introduced in detail below

组装钻井定点堵漏的装置。According to the lost formation conditions, estimate the size of the lost space (voids, fissures, and caves) on the well wall, and calculate the volume of the plugging material that needs to be squeezed into the lost space on the well wall according to the size L of the lost space on the well wall, and calculate according to the volume of the plugged material The volume of the plugging casing, the length of the casing and the length of the central sliding rod are connected together, and the plugging material is loaded into the space between the casing and the central sliding rod. Assuming that the inner diameter of the casing 12 is d, and the outer diameter of the central sliding rod 11 is D, the leakage space on the wellbore wall is L, and the minimum length of the casing string that needs to be connected is

Assemble the device for fixed-point plugging in drilling.

Calculate the distance from the lower part of the drilling fixed-point plugging device to the wellhead according to the position of the leakage point on the well wall, connect the upper joint 2 of the plugging device of the drilling fixed-point plugging device to the drill string 1, and connect the upper part of the drill string to the faucet. The mud pumps are connected by hoses.

Lower the position of the lower baffle of the fixed-point plugging device for drilling to the position of the leakage point on the well wall (generally the lowest part of the leakage point on the well wall), turn on the mud pump, and the mud pump will inject liquid from the inside of the drill pipe, and use it under the mud pressure. The plugging steel ball seals the sliding sleeve inside and moves downward. Under the thrust of the sliding sleeve, the center sliding rod moves downward to open the lower sealing baffle. When the sliding sleeve moves to the position of the limit retaining ring, it stops and the mud passes through the diameter Squeeze the plugging material into the formation through the through hole and vertical through hole to achieve the purpose of fixed-point plugging and squeeze the plugging material into the formation, then lift the drill string and the fixed-point plugging device out of the wellhead to complete the plugging operation .

During the downhole process of the fixed-point plugging device for drilling of the present invention, because sometimes the drilling fluid is not completely lost, in order to reduce the buoyancy of the unleaked mud in the well on the device and avoid the instability of the well wall caused by mud pulsation, the mud in the well can be passed through the outer pipe. Hole 9 and sliding sleeve through hole 15 squeeze out the plugging steel ball and enter the inside of the drill pipe. When the whole device is lowered to the predetermined position, turn on the high-pressure mud pump, push the plugging steel ball 3 and the center sliding sleeve 7 under the mud pressure to cut off the pin 6, the center sliding sleeve 7 and the center sliding rod 11 slide down, and the bottommost The lower snap-in baffle 13 is opened with the casing 12, and the mud enters the casing through the radial through hole 16 and the vertical through hole 17, and squeezes the plugging material into the well wall to seal the lost space of the formation. The lower snap-in baffle acts as a lower limit to prevent the plugging material from entering the lower part of the wellbore.

This method can play the role of fixed-point plugging for the leakage point at any position in the wellbore, and overcomes the previous need to fill the plugging point with the plugging material to determine the entire wellbore, saves cost and plugging time, and achieves fast and efficient plugging leak purpose.

Claims (1)

1. The method for fixed-point plugging of well drilling is characterized in that comprising the following steps: 1) Calculate the volume of the plugging material that needs to be squeezed into the lost space on the well wall according to the size L of the lost space on the well wall; 2) Calculate and connect the plugging casing volume, casing length and center sliding rod length according to the volume of the plugging material; 3) Put the plugging material into the space between the casing and the center sliding rod, and assemble the device for drilling fixed-point plugging; 4) Calculate the distance from the lower part of the drilling fixed-point plugging device to the wellhead according to the position of the leakage point on the well wall, connect the upper joint of the plugging device of the drilling fixed-point plugging device to the drill string, and connect the upper part of the drill string to the faucet. Mud pumps are connected by hoses; 5) After the fixed-point plugging device for drilling is lowered to the leakage point on the well wall, the mud pump is turned on, and the mud pump injects liquid from the inside of the drill pipe. Under the mud pressure, the plugging steel ball seals the internal sliding sleeve and moves downward. Under the thrust of the sliding sleeve, the center sliding rod moves downward to open the lower sealing baffle, and stops when the sliding sleeve moves to the position of the limit retaining ring, and the mud squeezes the plugging material in through the radial and vertical through holes. Formation, to achieve the purpose of fixed-point plugging and squeeze the plugging material into the formation, and then lift the drill string and the device for fixed-point plugging out of the wellhead to complete the plugging operation.

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