RU2612693C1 - Method to reduce water inflow in production wells without lifting of downhole pumping equipment - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method involves injection of the gel forming composition into the formation through the annular space of the well left for maintenance and downhole pump change. The selective isolation operation is made simultaneously with well killing. Pumping is initially made with an open swab valve and with borehole fluid circulation through the well tubing to the manifold. After the gel forming composition reaches the borehole pump receiver, the swab valve is closed and the pumping is continued into the formation. After the gel forming composition, a saline solution is pumped into the formation with a relative weight necessary to kill the well. Upon the saline solution reaches the perforation interval and the required swab, saline solution, is injected into the formation, the valve opens, and saline solution injection of into the well continues with its circulation through the tubing to complete displacement of borehole fluid into the manifold.

EFFECT: method improves selective isolation conditions, especially in the conditions of reduced formation pressure by preventing the well-killing fluid absorption in preparation for the well servicing.

6 cl

Description

The invention relates to the selective isolation of flooded interlayers in productive sections of production wells that are flooded with regional water over the formation.

A known method for the selective isolation of flooded interlayers of a productive formation, which consists in pumping AKOR-2 reagent into the formation through a tubing string capable of forming a hard gel upon contact with formation water [1, analogue]. This gel prevents water breakthrough from the flooded layer into the well cavity during its operation. The selectivity of this method of waterproofing is justified by the inability to gel the AKOR-2 reagent in contact with oil, i.e. in oil saturated layers. The disadvantage of this method of waterproofing is the insufficient length of the rim of the gel formed only in the mixing zone of the pumped AKOR-2 and produced water.

A known method for the selective isolation of flooded interlayers of a productive formation, which consists in pumping AKOR-4 reagent [2, prototype] mixed with water into the formation through a tubing string. In this case, the selectivity of isolation is justified by the high phase permeability to water, with which the AKOR-4 reagent, a watered layer and low phase permeability to water of an oil-saturated layer are mixed. The advantage of this method is that the zone of gel formation coincides with the zone of the porous medium filled with pumped water with AKOR-4 reagent.

The main disadvantage of this method is the relative high cost of the process of limiting water inflow from the well due to the need for preliminary lifting of the deep pumping equipment (GNO) from it and lowering the tubing string into it, during which the waterproofing composition is delivered to the perforation interval during the operation. The need to lower the tubing string into the well to the perforation interval is associated with the need to strictly control the injection process in the BCP with respect to the expensive AKOR-4 reagent. An uncontrolled injection process can lead to the preservation of the reagent in the well cavity together with water and to the formation of a hard and hard to break gel there, to loss of circulation in the treated well. Therefore, work to limit water inflows using this technology is possible only with the help of a cattle brigade, which significantly increases the cost of the process.

SUMMARY OF THE INVENTION

The proposed method consists in pumping a selective gelling reagent into the BCP without first raising the GNO from the well and lowering the tubing string into it, i.e. without the use of cattle brigade; for this, a gel-forming reagent is injected into the formation through the annulus of a stopped well; this operation is carried out during the preparation of the well for the current well repair (TRS) by changing the deep pump simultaneously with its killing; as a result, after the operation to limit water inflows in the well, a saline solution remains in its cavity with the density necessary for its killing, and the highly permeable interlayers of PZP, usually absorbing the killing fluid, remain isolated by the gel rim; the duration of the operation will not exceed the duration of two cycles of killing the well; installation of a gel rim in the water-saturated part of the bottomhole zone will ensure the stability of the killing fluid column in the well from absorption by the formation and eliminate the need for subsequent repeated killing.

The problem and the technical result of the present invention is to reduce the time and money spent on operations to limit water inflows in production wells.

The method of selective isolation of water inflows in a well stopped for conducting TRS when using a solution of thermotropic gelling composition VIS-1 [3] or innovative multifunctional reagent IMR [4] is carried out by the following sequence of operations:

1. Checking the circulation in the well and the injectivity of the reservoir.

2. In the annulus of the well with an open buffer valve, 1-2 m ³ (not less than the sump volume) of relatively heavy saline may be pumped.

3. Further, after injection of a heavy fluid or, if it is not pumped, immediately after checking the circulation in the well and the injectivity of the formation, up to 100 m ³ of a VIS-1 or IMR solution with a lower specific gravity is pumped into the annulus.

4. As soon as the heavy saline solution approaches the depth pump filter, which is indicated by the measured accumulated injection volume relative to the estimated annulus volume, the buffer valve closes and the injection continues into the reservoir.

5. As soon as the heavy solution approaches the perforation interval, which is indicated by the measured accumulated injection volume relative to the internal volume of the production string, the injection stops for 2-4 hours to settle the heavy solution into the well sump.

6. To clean the production casing and tubing string from the residues of the VIS-1 or IMR compositions after the VIS-1 or IMR solution, 3-10 m ^{3 of} the saline buffer is pumped into the well annulus for subsequent discharge into the formation.

7. To improve the cleaning of the production casing and tubing from the composition of VIS-1 or IMR, 1 m ^{3 of a} viscous inverse emulsion based on marketable oil and emulsifier can be pumped further into the well with a life time at reservoir temperature of not more than 6 hours with a specific gravity of not lower than VIS-1 or IMR solution, in which the aqueous phase is a solution of hydrochloric acid and / or aluminum chloride, and the concentration of hydrochloric acid and / or aluminum chloride in the emulsion is chosen so as not to exceed the corrosivity of the salt solution in the same oviyah and as emulsifier used repellent ADB [5], or Neftenol NS [6] or Neftenol GSZ [7].

8. Next, a saline solution with a specific gravity necessary for its killing is pumped into the well through the annulus.

9. After a sharp increase in the injection pressure, indicating that the emulsion has reached the perforation interval, or after reaching the calculated volume of injection of the saline solution to kill the perforation interval, the buffer valve opens and the well is flushed with saline solution with the density required to kill the well until the well is completely removed to the reservoir .

10. Next, the injection stops at the technological sludge for 6-24 hours for gelation of the injected gel-forming composition in the PPP, for the destruction of the emulsion delivered to the interval and to the perforation channels, and for the reaction of the HCl solution released from the emulsion or resulting from the hydrolysis of chloride released from the emulsion aluminum with deposits in the perforation channels and with the remnants of the gel.

The insulating solution VIS-1 [3] is a composition of surfactants with the addition of aluminum salts, urea and modifying additives.

The innovative multifunctional IMR reagent [4] is a composition obtained on the basis of aluminum and carbamide salts with additives.

The ADB water repellent [5] is a hydrocarbon solution of condensation products of tall oil and oleic acid with polyethylene polyamine and is used in the form of 20% and 40% solutions in kerosene, diesel fuel, polyalkylbenzenes, olefins and polyolefins and their mixtures.

Emulsifier Neftenol NZ [6] is a hydrocarbon solution of esters of oleic, linolenic, and also resin acids. Grade 40 N includes an additional additive of ethoxylated alkyl phenol.

The emulsifier Neftenol NZb [7] is a hydrocarbon dispersion of esters of oleic, linoleic, linolenic, as well as resin acids and colloidal organobentonite.

  During the operation in the well to isolate the waterlogged layers according to the described technology, due to the lower cost of the composition, it is possible to pump a larger volume of the gel-forming rim, which will allow installing a large-sized waterproofing screen in the PZP. The injected gelling composition has selectivity [8], because does not form a gel in a hydrocarbon medium, due to the good dissolution of ammonia released in the process of hydrolysis in hydrocarbons. At the same time, high-quality jamming is performed, ensuring that there is no need for repeated jamming in the process of TRS. At the same time, the perforation zone is flushed from contaminants produced by acid. The proposed technology is relevant in conditions of reduced reservoir pressure, when killing the well is problematic due to absorption of the killing fluid by the reservoir. Under these conditions, after the gel-forming composition and the buffer fluid are injected into the formation, it is recommended to wait for gelation time, only then open the buffer valve and flush the tubing string to the collector with the kill fluid. The proposed technology allows in waterlogged wells to systematically and at lower cost to carry out work to limit water inflows in preparation for periodically conducted TRS.

Information sources

1. Yankovsky Yu.N. and other Properties and prospects for the use of water-insulating reagents such as AKOR // Oil industry. - 1984. - No. 8. S. 52-55.

2. Stroganov V.M., Stroganov A.M. and other water-filled formulations of AKOR and the processes of their gelation. Collection of scientific papers VNIIKRneft Issues of fastening and completion of wells. - Krasnodar. Ed. VNIIKRneft, 1991.

3. TU 2484-184-54651030-2015. Insulating composition VIS-1. Date of introduction 03/27/2015

4. TU 2484-159-54651030-2014. Innovative multifunctional reagent IMR. Date of introduction 02.07.2014

5. TU 2483-081-17197708-2003. Water repellent ADB. Date of introduction 03.07.2003

6. TU 2483-007-17197708-97. Emulsifier Neftenol NZ. Date of introduction of May 6, 1997

7. TU 2458-057-17197708-01. Emulsifier Neftenol NZb. Date of introduction May 21, 2001

8. Harlanov S.A., Silin M.A., Magadova L.A. et al. Development of a sediment-forming gel composition to enhance oil recovery in low permeable and heterogeneous formations // Oilfield business. - 2015, No. 1. S. 20-24.

Claims (6)

1. A method for the selective isolation of flooded interlayers of a productive oil reservoir, including the injection of a gel-forming composition into the formation through a well cavity, characterized in that the gel-forming composition is injected into the formation through the annulus of the well, which was stopped for maintenance on changing the downhole pump, and this operation is performed simultaneously with killing the well, and the gel-forming composition is a low-viscosity aqueous solution of the reagent at a concentration that allows formation Under the conditions, to obtain the gel in its entire volume not earlier than 6 hours after the start of injection, moreover, the injection is carried out initially with the open buffer valve and when the well circulates the fluid through the tubing to the collector, and when the gel-forming composition reaches the deep pump, the buffer valve closes and the injection continues in the reservoir, and after the gel-forming composition, the brine is pumped into the reservoir with the specific gravity necessary for killing the well, moreover, after the saline solution reaches the perforation interval and crush the required buffer - saline into the reservoir, the buffer valve opens and the injection of saline into the well continues when it circulates through the tubing until the well is completely displaced into the reservoir. 2. The method according to p. 1, characterized in that in the case of using hard gels to prevent their formation in the well sump in the annulus of the well before the gel-forming composition, a relatively heavy saline solution is pumped with a volume equal to the volume of the sump, when the heavy salt solution reaches the deep filter the buffer valve closes the pump, and when it reaches the perforation interval, the injection stops for the necessary time to lower the heavy solution into the sump, after which the injection into the gel reservoir is restored azuyuschego composition. 3. The method according to p. 1, characterized in that the compositions of VIS-1 or IMR are used as a gelling composition. 4. The method according to p. 1, characterized in that in order to improve the cleaning of the production string and tubing string from the remnants of the gel-forming composition and to control the injection of the gel-forming composition into the PPP between the buffered saline and the saline killing solution, 1 m ^{3 of} viscous inverse oil emulsion is pumped into the well with density equal to the density of the saline solution, based on salable oil and emulsifier. 5. The method according to p. 4, characterized in that the quality of the emulsifier to obtain the inverse emulsion uses ADB Water repellent, or Neftenol NZ, or Neftenol NZb. 6. The method according to p. 4, characterized in that for the subsequent cleaning of the well filter from the gel pumped into the bottom hole and from other sediments, the aqueous phase of the inverse oil emulsion pumped into the well contains a stimulating composition, which is used as a solution of hydrochloric acid and / or aluminum chloride capable of destroying it on contact with the gel.