RU205024U9 - Downhole milling cutter with an enlarged flushing channel for preparing a well for hydraulic fracturing - Google Patents

Abstract

The utility model relates to the oil and gas industry and is designed for drilling a cement nozzle, backwashing a well and cleaning the walls by milling and reaming. The task of the utility model is to prepare the well for running the packer under hydraulic fracturing in one trip. Downhole milling cutter includes a cylindrical body with flushing holes at the bottom end. The upper end of the cylindrical body has a connecting thread for connection to the drill pipe string. The lower end of the cylindrical body is reinforced with rows of carbide plates, which are soldered onto the blades. Between the blades there is a composite carbide material made of calibrated tungsten carbide chips in conjunction with a solder. In the lower part of the cylindrical body, between the blades, there are flushing holes, one of which has an increased diameter.

Description

The utility model relates to the oil and gas industry, namely to devices for well development, and can be used in directional and horizontal wells to prepare a well with a 114 mm liner for hydraulic fracturing (hereinafter referred to as hydraulic fracturing) using a milling cutter assembly consisting of from a downhole cutter with a diameter of 92 mm.

At the stage of well development, hydraulic fracturing is carried out to ensure the flow. The technology for preparing wells with a 114 mm liner for hydraulic fracturing operation consists of three trips: lowering a 95.3 mm bit with a D-75 turbodrill to re-drill a cement nozzle (bottomhole normalization), running a scraper to clean the casing walls in the installation interval a packer for hydraulic fracturing, a run-up of a funnel-pen for flushing the bottomhole in order to remove mechanical particles formed after re-drilling and clean the walls. Then the packer-anchor equipment is lowered and hydraulic fracturing is carried out.

At the same time, there are a number of restrictions: on the maximum flow rate of the flushing fluid (no more than 5 l / s), on the minimum inner diameter of the hydrocraper (12 mm). The indicated design features of the equipment do not provide high-quality well flushing before the secondary opening of the formation until the suspended particles coefficient is measured - MPC not more than (100 mg / l).

Known downhole cutter, described in patent RU No. 119386 IPC E21B 29/00, published on 08/20/2012. The specified cutter includes a cylindrical body, the upper end of which is threaded for connection to the drill pipe string, and on the lower end there are blades covered with hard-alloy material; between the blades at the lower end, there are flushing holes with small diameters of flushing channels.

The disadvantages of the cutter are:

- restrictions on the flow rate of the flushing fluid;

- lack of backwash capability;

- the need for an additional round-trip operation of the funnel pen for flushing the well.

Downhole cutter described in RU patent No. 111882 U1, published on December 27, 2011, was chosen as the closest analogue. The specified downhole cutter includes a cylindrical body with flushing holes at the bottom end. The upper end of the cylindrical body is threaded for attaching to the drill string, and the lower end is reinforced with rows of carbide cutters. In the lower part of the cylindrical body there are blades on which hard-alloy cutters are soldered, and the hard-alloy cutters are made in the form of stepped plates. Between the blades there is a composite carbide material made of calibrated tungsten carbide chips in conjunction with solder. In addition, the downhole milling cutter is equipped with stabilizers located in the middle of the cylindrical body. In addition, additional flushing holes are located in the lower part of the cylindrical body between the blades.

The disadvantages of the cutter are:

- restrictions on the flow rate of the flushing fluid necessary for removing mechanical cuttings from the bottom of the well, which does not ensure the lifting of mechanical particles from the bottom of the well;

- lack of backwash capability;

- the need for an additional hoisting-and-run operation of the funnel-pen to remove mechanical cuttings from the bottom.

The technical objective of the present utility model is to reduce the number of trips, which, in turn, will reduce the time required for the development and commissioning of wells.

The result of preparing the well for hydraulic fracturing in one trip is achieved due to the fact that the downhole milling cutter includes a steel casing with three flushing channels, one of which has an increased diameter, 3 times compared to the diameters of other flushing holes, to ensure the creation of the maximum possible flow rate of the flushing fluid (10-12 l / s) in order to ensure the removal of mechanical sludge from the bottomhole, formed as a result of destruction by the blades of the milling cutter and the possibility of back flushing without clogging the washing channels with mechanical sludge of a coarse fraction. On the lower end of the body, blades with brazed carbide plates are welded, between the blades there is a composite hard-alloy material made of calibrated tungsten carbide chips in conjunction with solder, the upper end of the steel body is equipped with threads for connection to the drill pipe string.

The choice of an enlarged diameter of one of the holes is due to the creation of the flow area as close as possible to the flow area in the milling cutter body, as well as to the reduction of friction losses when the fluid leaves the milling holes of the milling cutter, which will increase the flow rate of the flushing fluid, thereby creating conditions for creating a turbulent flow providing removal of mechanical sludge. The total cross-sectional area of the milling cutters used is 20% of the total flow area of the drill pipes. The selection of an enlarged hole allows to increase the flow area up to 60% of the total flow area of the drill pipes.

The advantage of the proposed design is that, together with the plates of hard alloy material, a composite hard alloy material made of calibrated tungsten carbide chips in a bond with solder is applied to the equipment. Such an implementation allows for the drilling of the cement nozzle, and the enlarged flushing channel located closer to the edge of the end part can be removed from the bottomhole (by creating a flushing fluid flow rate of more than 10-12 l / s) particles of mechanical sludge of different fractions, including due to reverse circulation of the flushing fluid, preventing clogging of the flushing channels.

The essence of the utility model is illustrated by a graphical representation.

FIG. 1 shows a general view of the downhole milling cutter.

Downhole milling cutter consists of a cylindrical body 1 (Fig. 2) with flushing holes 2 at the lower end 3. The upper end 8 of the cylindrical body 1 has a connecting thread 4 for connection to the drill pipe string. The lower end 3 of the cylindrical body 1 is reinforced with rows of hard-alloy plates 5, which are soldered onto the blades 6 located in the lower part of the cylindrical body 1. Between the blades 6 is a composite hard-alloy material 7 made of calibrated tungsten carbide chips in conjunction with solder. In the lower part of the cylindrical body 1, between the blades 6, there are flushing holes 2, one of which has an increased diameter, 3 times compared to the diameters of the other flushing holes.

The device works as follows.

The downhole milling cutter is connected by means of a connecting thread 4 to the drill pipe string and is lowered into the well. An axial load and torque is applied to the router while flushing fluid is supplied. Rows of carbide plates 5 begin to cut off the layer of the cement nozzle, abrading it into smaller particles (mechanical sludge), which is removed from the bottomhole by the circulation of the flushing fluid supplied through the flushing holes 2 at the lower end 3 of the cylindrical body 1. In addition, the flow section of the enlarged flushing channel 2, located in the lower part of the cylindrical body 1, between the blades 6, allows back flushing of the well bottom, designed to remove larger mechanical particles and high-quality cleaning of the bottom.

Technical and economic or other efficiency:

- reduction of the number of round-trip operations due to drilling and flushing of the well before the secondary opening of the formation before measuring the coefficient of suspended particles in one operation;

- reduction in the duration of the well development cycle.

Claims (1)

Downhole milling cutter with an enlarged flushing channel for preparing a well for hydraulic fracturing, including a cylindrical body with three flushing holes at the bottom end, one of which is three times larger than the diameters of other flushing holes, the holes are located at an angle to the end surface, the lower end is equipped with blades with reinforced rows of hard-alloy plates, between which there is a composite hard-alloy material made of calibrated tungsten carbide chips in a bundle with solder, the upper end of the cylindrical body has a thread for connection to the drill pipe string.

Images