RU2388909C1 - Swabbing method with well monitoring - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: tubing strings are lowered to the well. Liquid is removed from the well via the above tubing string. Packer and instruments are installed on anchors. Prior to swabbing, the well string is packered. Central hole at the end of tubing string is closed with a detachable valve. Liquid is removed from tubing string. If necessary, liquid is removed from inter-tube space through the hole made in lower part of that string. In case it is not required to remove liquid from inter-tube space, the tubing string closed with a detachable valve is lowered without adding the liquid to it and with air available in it. Detachable valve is taken out with a grab on the cable, or the well string is unpackered. Examination with instruments is performed and filter is cleaned at smoothly ascending fluid flow. Bottomhole pressure of fluid, at which the formation stops working at ascending flow, is approximately equal to the value of bottomhole pressure, at which the formation begins working at decrease of the well liquid level. Installation depth of bottomhole pump is calculated.

EFFECT: increasing swabbing depth, reducing the time required for it, smooth change of level and pressure of the well liquid, reliable and accurate recording of the processes performed in the well.

Description

The invention relates to the oil industry and can be used in monitoring wells, primarily multilayer, in the process of swabbing.

There is a known swabbing process consisting in scooping up fluid from a well with a rubberized cuff moved by a winch cable (Patents RU No. 96122104, 2099508, 2121565, 2135760, 2181830, 2183731, 2270912, US 4817712).

Lowering the level of fluid in the well reduces the hydrostatic pressure of the column of wellbore fluid in the formation zone, resulting in a depression on the formation, stimulating the flow of fluid from the formation and cleaning the filter.

It is also known to lower the liquid level in the well by swabbing or by a pump monitoring the well, including the descent of the tubing string into the well, removing fluid from the well through the specified tubing string, installing the packer in the string and instruments anchored (Patent RU 57359).

The disadvantage of this method is that the results of studies of downhole processes with instruments are inaccurate, unstable, not reflecting the true picture of what is happening.

The reason for such shortcomings is that the swabbing process is intermittent and fleeting, with a quick separation of the rising liquid column from the bulk of the liquid. Under such pulsating and rapid changes in the pressure of the well fluid, the processes occurring in the well are also fleeting and difficult to fix with instruments.

In addition, the swabbing process is very lengthy due to the fact that when the level of the liquid in the well decreases, the formation increases the flow of fluid into the well in proportion to the amount of decrease in the level of fluid in the well. The swab process under these conditions is slowed down and may stop altogether if its productivity is less than the productivity of the formation at a certain level of fluid in the well. Due to the above, the swab depth is also limited.

The objective of the invention is to remedy the above disadvantages.

The technical result achieved by using the present invention is to increase the swab depth, reduce its time, as well as a smooth change in the level and pressure of the fluid in the well, providing reliable and reliable fixation of the processes occurring in the well.

The specified technical result is achieved by the fact that in the swab method with monitoring of the well, including the descent of the tubing string into the well, the removal of fluid from the well through the specified tubing string, the installation of the packer and instruments on the anchors according to the invention, the packer is packed with a packer before swabbing, mounted at the end of the tubing string; the central hole at the end of the tubing string is closed with a removable valve; liquid is removed from the tubing string, and if necessary, liquid is also removed from the annulus through an opening in the lower part of this column; in the absence of the need to remove liquid from the annulus, the tubing string closed by a removable valve is lowered without liquid being poured into it with the presence of air in it; after the end of swabbing or after the descent of an empty string of tubing closed by a removable valve, remove the removable valve on the cable with a catcher or unpack the well string; instrumentation and filter cleaning are performed on a smoothly rising fluid flow; bottomhole fluid pressure, at which the reservoir ceases to work with an upward flow, approximately equal to the bottomhole pressure at which the reservoir begins to work when the fluid level in the well decreases; the depth of installation of the production pump is calculated according to the specified bottomhole pressure from the conditions of working capacity of the reservoirs.

The fact that before the start of swabbing, the well string is packaged with a packer installed at the end of the tubing string, while closing the valve in the tubing with the valve, it is possible to disconnect the under-pack fluid from the fluid column above the packer. In this case, it becomes possible to swab only the liquid column above the packer without swirling fluid from the reservoirs. This allows the swabbing time to be reduced several times and the swabbing depth with a decrease in the liquid level in the tubing and the string by 1.5-2.0 times. If the packer provides reliable sealing of the column, then it will become possible not to remove the liquid from the annulus, but to remove it only from the tubing string, as a result of which the swab time will be reduced by a further 3 times, since the volume of the annulus exceeds the volume inside the tubing by 3 times.

Closing the central hole at the end of the tubing string with a removable valve allows us to achieve a decrease in both the time and depth of swabbing while closing the annulus with a packer, as described in the paragraph above.

Removing fluid from a tubing string closed at the end by a valve is the highest performing swab option due to the absence of the need to remove fluid from the annulus, the volumes of which are related as 1: 3.

The provided possibility of removing swabbing fluid from the annulus through the hole in the lower part of the tubing string allows, if necessary, to extend the time and rate of restoration of the fluid level in the well three times after removal of the removable valve. This ensures a smooth change (increase) in the level and pressure of the fluid in the well, providing reliable and reliable fixation of the processes occurring in the well.

The descent of the tubing string closed by a removable valve without pouring liquid into it with the presence of air in it, if there is no need to remove the liquid from the annulus, allows to obtain an even better result both in the time of preparing the well for research and in the depth of lowering the liquid level in Tubing. This is due to the fact that it is not necessary to remove liquid from the empty tubing string at all, and the depth of lowering the liquid level in the tubing string in this case is initially at the level of the removable valve, i.e. it is the maximum possible.

The removal of a removable valve on the cable by the catcher or unpacking of the well string after swabbing or after releasing an empty tubing string closed by the removable valve opens up the possibility for the fluid to leave the reservoir, since the low level of fluid in the well creates a depression on the reservoir, and the reservoir pressure work actively until the fluid reaches a dynamic level. The best result is achieved when the empty tubing string is turned on when the depression on the formation is the maximum possible.

The presence of a smoothly ascending fluid flow provides both filter cleaning and fixing by the research instruments of reliable and reliable information about the processes occurring in the well.

The ability to approximately equal the values of bottomhole pressures when rising and with a decrease in the liquid level in the well is based on the law of the identity of the phenomena occurring in the bottomhole zone of the formation with equal formation and bottomhole pressures. If these pressures are equal, the reservoir does not work. If the bottomhole pressure is lower than the reservoir pressure, then the reservoir begins to work. It doesn’t matter how the formation and bottomhole pressures are equal - with a decrease in the liquid level in the well or, conversely, with its increase. The result will be the same. This phenomenon just allows to achieve a positive result in the proposed method: instead of the difficulties of fixing the ongoing processes with an unstable decrease in the liquid level during swabbing, the prototype has the possibility of reliable and reliable fixation of the same processes with a smooth increase in the liquid level in the well after preliminary lowering the liquid level by swabbing.

Since the obtained value of the bottomhole pressure is scientifically sound and reliable, using it as the initial value for calculating the installation depth of the production pump ensures that it is also under this condition that the reservoir performance will also be reliably ensured.

Since for the implementation of the proposed method uses the usual equipment known from analogues and prototype, the drawings of the device for implementing the method are not attached.

The method is implemented as follows.

First, anchors with suspended research instruments are installed over each layer.

Then the tubing string is lowered into the well, at the end of which a packer for the well string is installed, and a removable valve is installed in the tubing hole.

After lowering the tubing string to a predetermined depth, the string is packaged and swabbing is started.

The fluid is removed from the tubing string if, according to the calculation, the time and speed of the fluid rise in the well after the end of the swab will provide reliable information about the processes taking place, recorded by the devices.

If a smoother fluid rise in the well is required to provide reliable information, then the fluid is also removed from the annulus. For this, a hole is made in the tubing string either in advance or after the tubing is lowered using a piercing, drilling or other perforator.

The absence of fluid inflow from the formation during the swab process allows not only to perform it with high productivity, but also to provide any estimated swab depth.

The best result in creating the maximum depression on the formation is achieved if an empty tubing string closed by a valve is lowered into the well. In this case, swabbing is not necessary.

After swabbing or a removable valve is removed with a catcher on the cable or the column is unpacked. After the empty tubing string is lowered, only the removable valve is opened, and the columns are not unpacked to maintain the lowest possible liquid level in the well at the level of the removable valve.

In all cases, the very low level of fluid remaining in the well creates an extremely large level of depression on the formation, especially when opening an empty tubing string.

The formation begins to work with a whistle, cleaning both the filter and the bottom-hole zone of the formation with the outgoing fluid and raising the level of fluid in the well.

Autonomous research instruments record all processes occurring in the well, including the values of bottomhole pressures at which each individual formation ceases to produce fluid into the well. This value will be used to reliably calculate the installation depth of the production pump, which ensures high productivity of the reservoirs.

Claims (1)

A method of swabbing with monitoring a well, including lowering a tubing string into a well, removing fluid from a well through said tubing string, installing a packer and instruments at anchors, characterized in that before swabbing, the well string is packaged with a packer installed at the end of the tubing string pipes, the central hole at the end of the tubing string is closed with a removable valve, liquid is removed from the tubing string, and through the hole in the bottom of this string if necessary, remove liquid from the annulus or, if there is no need to remove liquid from the annulus, the tubing string closed by a removable valve is lowered without liquid being poured into it with air in it, after swabbing is completed or after the empty tubing string closed by a removable valve is lowered , a removable valve is removed by a catcher on the cable or the well string is unpacked, studies with instruments and filter cleaning are performed on a smoothly upward fluid flow, bottomhole pressure e fluid, wherein the reservoir stops working during an upward stream, approximately equate the value of bottom hole pressure at which the layer starts to operate at low fluid level in the well, pump and mining installation depth calculated by said bottomhole pressure of the reservoir performance conditions.