RU55869U1 - DEVICE FOR CLEANING A WELL AFTER HYDRAULIC FRACTURE - Google Patents

Abstract

The device relates to the field of oil production, to equipment for the production and operation of oil and gas wells. The device allows to improve the process of cleaning the well from solids with a frack string installed due to the fact that a frack string is used as the outer column of the tubing, a sealing element is installed in the space between the frack string and the inner string of the tubing, allowing reciprocating movement of the inner string with a jet pump, frack and inner columns are installed with a gap, forming an annular annular between them space for pumping hydraulic fluid, wherein the inner column is arranged to mixing it selects and working fluids in their motion. The sealing element can be made in the form of a cuff. The jet pump may be removable or non-removable. 1 ill. 2 zpf

Description

The proposed device relates to equipment for the production and operation of oil and gas wells, and more particularly to equipment for putting a well into operation after hydraulic fracturing.

The technology of hydraulic fracturing is to create extended cracks in the reservoir under the action of pressure exceeding the fracture strength of the rock. To prevent the crack from collapsing after relieving pressure, a mixture of granular material called proppant is pumped into the crack. The proppant granules fill the fracture and keep it open after depressurization and during the operation of the well. In most cases, fracking operations are performed on wells that are not gushing and require the use of mechanized production methods. As such a production method, submersible electric centrifugal pumps (ESPs) are used. Before the pump is lowered into the well, the frac column of tubing with a packer is removed from the well. In many cases, the presence of a proppant that did not enter the crevice and settled in the well and inside the coat column prevents the extraction of the column from the well. In this case, the descent of the column of small diameter into the coat column and the washing of the proppant by reverse circulation is necessary. After completion of the cleaning process, the packer can be torn off its seat and the coat column is removed from the well.

The initial period of operation of the well is characterized by a large number of carried out mechanical impurities. The bulk of the solids is represented by loose proppant carried out from the reservoir crack. The presence of proppant in the sampled fluid also leads to the rapid decommissioning of the ESP.

The use of a “victim” pump at the initial stage of well operation is one of the most common proppant treatment methods. As a pump "victim" use a pump that was under repair.

The above explains the importance of high-quality proppant cleaning of the well for the possibility of extracting the coat column and for the trouble-free operation of the ESP.

A device for a jet pump used for well development is selected as an analogue (RU No. 2202039 Method for the development, research and operation of wells).

The advantage of an inkjet pump, in contrast to an ESP, is the ability to select liquids with a high content of solids. The known pump scheme is used to develop the well after hydraulic fracturing before installing the ESP. The disadvantages of the analogue are the inability to reciprocate the movement of the device along the wellbore, as well as the inability to use it to clean the mechanical impurities with a fitted column.

The closest technical solution (prototype) is a device using a double-column jet pump (A. Drozdov "Advanced technologies for oil production using submersible pumps" Oil and Gas Eurasia, December-January 2003-2004). Compared with the analogue, this scheme allows for reciprocating motion along the wellbore. However, as in the case of the analogue, for the application of this arrangement, the frac column must be removed from the well.

This drawback is eliminated by the fact that the device for cleaning the well after hydraulic fracturing, containing a single pipe string with a jet pump installed on it, is placed inside the coat string, and a sealing element is installed in the space between the coat string and the inner string, allowing

to perform reciprocating movement of the column with the jet pump inside the coat column.

The sealing element may be made in the form of an elastic cuff.

Figure 1 on the left shows the design of the well with the installed frac column. Figure 1 on the right shows a device for cleaning a well after hydraulic fracturing with a jet pump located inside the coat string.

The well design with the proposed device includes a casing 1 with a perforation interval 2. The line-up consists of a string of tubing 3 with a packer 4. A packer 4 is installed above the perforation interval. The proppant that did not fall into the fracture and settled on the bottom of the well is conventionally represented by number 5. The device for cleaning a well after hydraulic fracturing, shown in Fig. 1 to the right, includes a tubing string 6 of small diameter, a shank 9, a jet pump 7 and a seal 8. The outer diameter of the shank 9 is less than the inner diameter of the packer barrel 4, which allows you to place the shank in the packer barrel and reach the bottom of the well. The seal 8 is made in the form of a cuff, providing tightness between the inner diameter of the coat column 3 and the outer diameter of the inner column 6, when pressure is applied from the upper side of the cuff. The jet pump can be made in removable and non-removable versions and includes a nozzle 11, a mixing chamber 12, a check valve 13 and a hole for the inlet of the working fluid 14. Figure 1 shows the installation diagram of the jet pump, in which the working fluid is supplied through an annular gap 10 between the frack column and the inner column, and the mixture of working and withdrawn liquid is transported to the surface inside the column 6. This scheme is more reliable from the point of

view of reducing the likelihood of sticking when removed from the coat column.

The proposed device operates as follows. The described line-up with a jet pump is placed inside the coat column. The length of the liner 9 is selected so that when the restrictive ring 15 is planted in the packer barrel, the liner 9 reaches the bottom of the well. The descent of the column is carried out until the bottom of the liner 9 touches the proppant, presented in the form of proppant plugs formed inside the coat column 6 or proppant that has settled on the bottom of the well. Then the column is raised a few meters and the circulation of the working fluid begins in the annular gap 10. Water can be used as the working fluid. Simultaneously with the circulation begin to slowly move the column 6 down. The working fluid through the channel 14 is directed into the nozzle 11 of the jet pump. The created vacuum carries the proppant granules with the borehole fluid along the liner 9 into the mixing chamber 12, and then they are lifted along the column 6 to the surface. Separation of solids is performed on the surface, and the working fluid is recycled to the well. In the process of moving the column 6 down, this process is combined with the reciprocating movement of the column to prevent sticking and more effective cleaning of the well.

The claimed technical solution allows the well to be cleaned without removing the frac column and is more effective in comparison with the existing methods of well development after fracturing.

Claims (3)

1. A device for cleaning a well after hydraulic fracturing, comprising two columns of tubing arranged one in the other, with a jet pump installed on the inner string, characterized in that the outer tubing string is a frack string, in the space between the frack string and the inner string the tubing has a sealing element that allows the reciprocating movement of the inner column with a jet pump, frack and inner columns anovleny with a gap therebetween forming an annular space between the tubes for pumping hydraulic fluid, wherein the inner column is arranged to mixing it selects and working fluids in their motion. 2. The device according to claim 1, characterized in that the sealing element is made in the form of a cuff. 3. The device according to claim 1, characterized in that the jet pump can be made removable or non-removable.