Method for isolating absorption zone in a well. RU patent 2245987.

IPC classes for russian patent Method for isolating absorption zone in a well. RU patent 2245987. (RU 2245987):

E21B33/13 - Methods or devices for cementing, for plugging holes, crevices, or the like (dump bailers E21B0027020000; chemical compositions therefor C09K0008000000)

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Method for isolating absorption zone in a well / 2245987
Method includes lowering feeding column into well with mounting of its shoe above ceiling of absorption zone. Along feeding column portions of working liquid are fed into well. As the latter alkali waste of kaprolaktam production or its solution is taken. Working liquid is alternated with portions of its thickener - sodium silicate; alternated by water buffers. Working liquid is pumped at consecutively decreasing concentration. Water buffers are pumped at consecutively decreasing volume. After output from feeding column of first portions of working liquid and its thickener, pumping is continued in cyclic mode with periodical stops of pumping from waves generation condition in such a way, that straight and reflected pressure waves interact in well shaft above absorption zone and below this zone.

Method for isolating fluid-influx area in a well / 2245988
Method includes forming a screen of viscous-elastic mass in well via interaction of working liquid pumped into well in form of alkali waste of kaprolaktam production or its solution, with influx liquid. Necessary speed of transformation of viscous-elastic mass and intensiveness of filling of well adjacent area with it is adjusted by mode of pressing of working liquid into influx zone. For this purpose pressure increase is alternated with pressure decrease. Pressure is decreased for 10-50% from achieved maximum pressure. Relation of exposure time for increased pressure to decreased pressure time is taken in limits 1.1-5.0.

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes lowering feeding column into well with mounting of its shoe above ceiling of absorption zone. Along feeding column portions of working liquid are fed into well. As the latter alkali waste of kaprolaktam production or its solution is taken. Working liquid is alternated with portions of its thickener - sodium silicate; alternated by water buffers. Working liquid is pumped at consecutively decreasing concentration. Water buffers are pumped at consecutively decreasing volume. After output from feeding column of first portions of working liquid and its thickener, pumping is continued in cyclic mode with periodical stops of pumping from waves generation condition in such a way, that straight and reflected pressure waves interact in well shaft above absorption zone and below this zone.

EFFECT: higher efficiency.

6 cl

The present invention relates to the field of oil and gas industry, in particular to the isolation zones acquisitions in the oil or gas well during drilling and/or operation. During operation, well we can talk about the elimination of the absorption zone, timed to coincide with the intervals of violations of the casing.

The known method of isolation zones absorption in the well by the injection into it of insulating material (see, for example, Abdrakhmanov G.S., and others, the Study and isolation of absorbing layers in the process of wiring holes, TNT, Series Drilling, Moscow, VYING, 1973, p.106-107).

The disadvantage of this method is its low efficiency because of the possibility of dilution of the insulating mixture downhole fluid and limitations on the use of viscous liquids.

The technical result of the invention is to improve the efficiency of the isolation zone absorption in the borehole due to the possibility of application of insulation systems of high viscosity and control their viscosity under the conditions of the well.

Required technical result is achieved in that the method of isolation of the absorption zone in a borehole includes a descent into the borehole filling the column with the installation of her Shoe on the roof of the absorption zone, the injection into the well by casting the column portions of the working fluid, alternating with portions of its thickener through the rim water, separating the thickener from the working fluid, which is pumped with a progressively decreasing concentration, and the rim water - with progressively smaller volume, while after leaving the filling of the column in the well of the first portions of the working fluid and thickener downloads continue in a cyclic mode with periodic stops injection of the conditions for generating pressure waves in such way that the direct and reflected pressure waves interact in the wellbore above the absorption zone or below this zone.

In addition:

as the working fluid take alkaline water flow in the production of caprolactam ((AEA), and as a thickener is sodium silicate;

as rims waters are fresh water;

concentration (AEA reduce to 1.5% due to its dissolution in fresh water;

sodium silicate is in the form of an aqueous solution with a concentration of 8-15%;

(AEA pumped from the calculation of 1-3 m 3 1 m thick zone of absorption and sodium silicate at the rate of 0.5-1 m 3 1 m thickness of the absorption zone;

as the last portion of the pumped cement and/or cement mortar with addition of 0.1-1.5% of the volume of water required for hydration of the cement.

The invention consists in that it allows to eliminate the absorption in the hole almost any degree of complexity due to the possibility of applying an insulating liquid high viscosity. Liquid of high viscosity is prepared directly in the well, because the injection of such fluid in finished form from the wellhead existing tools (pumps) is not always possible or effective. In one case, the pumps can, in principle, to provide injection of fluid of high viscosity. In another case, the pumps, if and can provide the injection of a certain degree of viscosity, but they destroy the structure of this liquid, which loses its insulating properties.

The insulating liquid of high viscosity to provide mixing in the borehole fluid, for example, alkaline runoff production caprolactam ((AEA) or its aqueous solution with a water solution of sodium silicate.

Insulating liquid with a sufficient degree of viscosity can also be obtained by mixing in the borehole (AEA with calcium chloride or mylanta with calcium chloride.

First portions of the insulating fluids provide maximum viscosity to ensure that the water seal and prevent catastrophic absorption. With the passage of time from the beginning of the insulating increases the risk of spontaneous formation of thickened fluid filling the borehole, further complicating the implementation of insulation work and possibly even their exclusion. Therefore, further downloading of portions of the working fluid is performed with progressively decreasing concentration. While rim water pump with progressively smaller volume to increase the reliability of mixing the working fluid with its thickener. In addition, after leaving the filling of the column in the well of the first portions of the working fluid and thickener there is a possibility of a longer time of exposure to mixing.

A feature of the invention is a process of forced mixing the working fluid with its thickener. To do this, after you exit the priming column in the well of the first portions of the working fluid and thickener downloads continue in a cyclic mode with periodic stops pumping. This ensures the generation of a shock wave pressure. In advance empirically in downhole conditions using pressure sensors in the borehole, the pressure control on the mouth and subsequent mathematical modelling fulfill these conditions generate pressure waves to direct and reflected waves interact in the wellbore above the absorption zone or below this zone.

In the interaction of direct and reflected pressure waves above the absorption zone (in front of a multidirectional pressure waves), where we are coming from pouring the column portion of the working fluid and thickener, creating optimal conditions for their mixing. This mixing and subject to a maximum initial concentrations of the reacting liquids the viscosity of the resulting insulating fluid increases in a power-law dependence. The response to this is the increase in pressure produce the liquid in the absorption zone. To avoid undesirable effects (peripheral front pressure) portion of the liquid in the grout column is necessary to periodically change the parameters of cyclic injection regime so that direct and reflected pressure wave would interact and below the zone of absorption. This consists of adjusting the viscosity of the insulation liquid during its release into the wellbore from pouring columns. To move a zone of interaction of pressure waves in the wellbore change, for example, frequency and/or amplitude and/or period of cyclic effects (periods stop injection and/or pressure injection, and/or dynamics of increasing the pressure of injection, and/or dynamic pressure relief injection).. the Method is as follows.

Before isolation allocated in the well area of the absorption spend its hydrodynamic studies. Determine the nature of the absorption liquid, the static and dynamic levels, and the nature of the response of the well to the change in viscosity of the injected fluid.

Check the well response in cyclic mode with registration at the wellhead and downhole pressure parameters and fixing zones of interaction of direct and reflected waves of pressure in the wellbore, depending on the mode of cyclic injection. Then lowered into the well casting the column. Shoe of the column set, for example, 10-15 m above the roof zone of absorption. Pumped into the well by casting the column portion of the working fluid, for example, (AEA, which alternate with portions of its thickener, for example, sodium silicate. (AEA pumped from the calculation, for example, 2 m 3 1 m thick zone of absorption and sodium silicate at the rate of 0.7 m 3 1 m thick zone of absorption. The first portion (AEA take, for example, 100% concentration. The last portion (AEA, depending on the nature of the absorption zone may be taken with a concentration of 1.5%. (AEA is dissolved in water, for example, fresh. The concentration of sodium silicate is, for example, 15%. It is also dissolve in water, for example, fresh. Between portions of the working fluid, for example, (AEA and thickener, for example, sodium silicate download fringe of water to separate them and prevent premature mixing and thickening in the grout column. Thickener (sodium silicate) pumped with a progressively decreasing concentration of, for example, to 8% in the final portion. While rim water pump with progressively decreasing volume. After leaving the filling of the column in the well of the first portions of the working fluid, for example, (AEA, and thickener, for example, sodium silicate, downloads continue in cyclic mode.

This injection is performed with periodic stops of the conditions for generating pressure waves so that the direct and reflected waves interact in the wellbore above the absorption zone or below this zone. Cyclic mode is accompanied by changes in, for example, frequency and/or amplitude and/or period of cyclic effects. To do this, change the periods stop injection and/or pressure injection, and/or dynamics of increasing the pressure of injection, and/or dynamic pressure relief injection. The degree of mixing of the working fluid and thickener determine, ultimately, the viscosity of the insulating liquid, and therefore the success of the isolation zone of absorption. During the process of isolation of the control pressure at the wellhead and in her trunk, if necessary, as well as changes in air pressure..

1. Way to isolate the zone of absorption in the well, including the descent into the well filling the column with the installation of her Shoe on the roof of the absorption zone, the injection into the well by casting the column portions of the working fluid, which take alkaline runoff of caprolactam - (AEA or its solution, which alternate with portions of the thickener fluid - sodium silicate through the rim water, separating the thickener from the working fluid, which is pumped with a progressively decreasing concentration, and the rim water - with progressively smaller volume, while after leaving the filling of the column in the well of the first portions of the working fluid and thickener download continue in cyclic mode with periodic stops injection of the conditions for generating pressure waves so that the direct and reflected pressure waves interact in the wellbore above the absorption zone or below this zone.

2. The method according to claim 1, characterized in that as rims waters are fresh water.

3. The method according to claim 1, characterized in that the concentration (AEA reduce to 1.5 % due to its dissolution in fresh water.

4. The method according to claim 1, wherein the sodium silicate is in the form of an aqueous solution with a concentration of 8-15%.

5. The method according to claim 1, characterized in that (AEA pumped at a rate of 1 - 3 m 3 1 m thick zone of absorption and sodium silicate at the rate of 0.5 - 1 m 3 1 m thick zone of absorption.

6. The method according to claim 1, characterized in that as the last portion of the pumped cement slurry.