RU2330932C1 - Method of bridge installation for well bottom insulation - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention concerns well construction and recovery. The method involves delivery of backfill material in a container through a fluid column to the well bottom, damage of container integrity, solidification of the backfill material due to its interaction with the water-based well fluid, and subsequent bridge formation. The container has through orifices with temporary stopgaps to keep the container insulated. Container's weight sufficient to submerge it to the well bottom is calculated based on the container volume and well fluid density. Container integrity is damaged by dissolution of temporary stopgaps in the well fluid. Polyvalent metal salts are used as temporary stopgaps. As the backfill material a reagent or composition solidifying in short time with multifold volume boost is used.

EFFECT: improved efficiency of well bottom insulation.

1 ex

Description

The invention relates to the oil industry, in particular to the construction and repair of wells, and can be used to seal the cased hole bottom and temporarily shut off the formations.

Known flap for installing a cement bridge at a given interval of the well [RF patent No. 2268349, EV 27/02, BI No. 2, 2006]. The bailer descends into the borehole on the rope and ensures the installation of cement bridges regardless of the liquid column above the bailer.

The disadvantage of the method of installing bridges using the choke is that for the descent of the chute on the rope it is necessary to use special equipment, which is absent in many enterprises associated with well repair.

The closest technical solution to the proposed (prototype) is a method of isolating absorbing formations in a well, including the delivery of grouting material to the bottom of the well in the container along the column of liquid, the destruction of the integrity of the container and the curing of the grouting material when interacting with a well-based water-based fluid to form a bridge [patent RF №2179229, ЕВВ 33/13, BI №4, 2002].

The disadvantage of this method is that in the process of stopping the injection (holding the grouting mortar for the period of loss of mobility), the grouting mortar is diluted with produced water, as a result, the initial concentration of the mortar is violated and, as a result, the stability of the resulting insulating barrier is worsened, and the strength of the groutstone is reduced, which does not provide reliable isolation of the reservoir and indicates the local nature of the action of this method. In addition, this method is time-consuming, associated with a large investment of time, increasing the duration of the repair and insulation work, and for its implementation it is necessary to use drill pipes.

The technical objective of the proposed method is to increase the efficiency of sealing the cased hole bottom by installing a bridge and temporarily shutting off productive formations by reducing the curing time of grouting material with a multiple increase in volume, which ensures the continuity of subsequent technological operations, reduces the duration of repair and insulation works and the complexity.

The problem is solved by the method of installing a bridge for sealing the bottom of the well, including the delivery of grouting material to the bottom of the well in the container along a column of liquid, the destruction of the integrity of the container and the curing of the grouting material when interacting with a water-based wellbore fluid to form a bridge.

What is new is that a container with through holes is used, temporary plugs are installed in these holes to ensure the tightness of the container, the weight of the container is determined depending on the volume of the container, the density of the borehole fluid, which ensures its immersion in the bottom of the well:

_To P> V · ρ _{to the compression channel,}

where P _to - the weight of the container;

V _to - the volume of the container;

ρ _{compress the} density of the well fluid,

destruction of the integrity of the container is carried out by dissolving the filling holes in the container of temporary plugs with well fluid, as solids of polyvalent metals well soluble in the well fluid, are used as temporary plugs, and a reagent or composition is used as a grouting material, curing of which takes place over a short period of time with a multiple increase in volume .

The essence of the proposed method is to seal the cased hole bottom with a bridge of grouting material that cures with a multiple increase in volume when interacting with a water-based fluid of any mineralization. As a grouting material, you can use a urethane prepolymer or a composition based on modified quicklime, a mixture of lime for mining and drilling (SIGB), etc. Grouting material is delivered to the bottom of the wells in a container, which is discharged from the wellhead into the wellbore, filled with borehole fluid.

The container has through holes, temporary plugs are installed in these holes to ensure the tightness of the container.

The container may be made of thick cardboard, plastic or similar materials. The weight of the container with the grouting composition is determined in compliance with the conditions for its immersion in the well fluid:

_To P> V · ρ _{to the compression channel,}

where P _to - the weight of the container;

V _to - the volume of the container;

ρ _cf is the density of the well fluid.

As a temporary water-soluble cork, salts of polyvalent metals are used: calcium chloride, magnesium, etc.

If the well fluid has a high density, then the container with grouting material is weighted with a load of easily drilled material. The dimensions of the container are determined from the condition of its free passage through the wellbore and the containment of grouting material in an amount sufficient to form a bridge of the required height in the wellbore. If the volume of grouting material that fits in the container is not enough to form a bridge of the required height, then two or more containers are dropped into the well in turn. After immersion in the bottom of the container with the grouting material, the water-based fluid in the well dissolves the water-soluble plug with which the holes are sealed. After depressurization of the holes, the water-based well fluid interacts with the grouting material and the latter cures. The curing reaction of urethane prepolymers is characterized by a high speed, the curing start time is 20-300 s, and a small amount of well fluid is sufficient for it to flow. A grouting mass formed during curing destroys the container and forms a bridge in the wellbore that seals the bottom of the well, the volume of which is many times greater than the volume of the original grouting material. The cement mass formed during curing has high adhesion to metal and retains its strength properties under the influence of formation fluids, such as oil and produced water of varying degrees of mineralization, as well as in acetone, concentrated and dilute solutions of hydrochloric, nitric, and nitrilotrimethylphosphonic acids. If the bridge resulting from the curing of the prepolymer is too high, then it can be easily drilled to the required depth. If the sump of the well has a shallow depth, the proposed method can be applied to temporarily shut off the formations. In this case, when the need arises, the bridge from the cured prepolymer in the interval of the production filter can be dissolved with formic acid.

An analysis of the patent and scientific and technical literature allowed us to conclude that there are no technical solutions containing essential features of the claimed method that perform a similar task, therefore, we can state the compliance of the proposed method with the criterion of "novelty" and "inventive step".

An example implementation of the method.

An oil well cased with a production casing with a nominal diameter of 168 mm, with a production filter interval of 990-1000 m and a current bottom of 1050 m, has been flooded by geophysical surveys as a result of leakage in the bottom. A decision was made to seal the face by installing a bridge. Clarify the density of the well fluid. The well overhaul team performs the lifting of deep pumping equipment and washed the bottom of the well.

The weight of the container is determined depending on the volume of the container, the density of the borehole fluid, ensuring its immersion in the bottom of the well:

_To P> V · ρ _{to the compression channel,}

where P _to - the weight of the container is 20 kg,

V _K is the volume of the container,

ρ _cf is the density of the well fluid.

With a container height of 1 m and a diameter of 130 mm, the volume of the container is 0.013 m ³ . The density of the borehole fluid is 1160 kg / m ³ .

20 kg> 0.013 m ³ · 1160 kg / m ³

20 kg> 15.4 kg

The inequality conditions are met, which ensures the immersion of the container on the bottom of the well.

Two containers with a height of 1.0 m and a diameter of 130 mm are thrown into the production casing with through holes sealed with temporary plugs from a concentrated solution of calcium chloride. As the plugging material used urethane prepolymer under the trademark Hycel-OHlA (Japan) at a density of 1080 kg / m ^3. The containers are loaded into the bottom along a column of well fluid in a static state. The well fluid dissolves calcium chloride in the holes and interacts with the grouting material, as a result of which a grouting mass increases in volume over 200 s, destroying the container, and a bridge forms at the bottom of the well.

Thus, in this proposal, the result is achieved - increasing the efficiency of sealing the cased hole bottom by installing a bridge and temporarily shutting off productive formations by reducing the curing time of cement slurry with a multiple increase in volume, which ensures the continuity of subsequent technological operations, reduces the duration of repair and insulation works and the complexity .

Claims (1)

A method of installing a bridge to seal the bottom of the well, including delivering grouting material to the bottom of the well in a container along a column of liquid, destroying the integrity of the container and curing the grouting material when interacting with a water-based wellbore fluid to form a bridge, characterized in that a container with through holes is used, temporary plugs are installed in the indicated holes, ensuring the tightness of the container, the weight of the container is determined depending on the volume of the container, tightly the borehole fluid, ensuring its immersion in the bottom of the well: _To P> V · ρ _{to the compression channel,} where P _to - the weight of the container; V _to - the volume of the container; ρ _{compress the} density of the well fluid, destruction of the integrity of the container is carried out by dissolving the filling hole in the container of temporary plugs with well fluid, as solids of polyvalent metals well soluble in the well fluid as temporary plugs, and a reagent or composition is used as grouting material, curing of which takes place over a short period of time with a multiple increase in volume .