RU2299308C2 - Water-bearing bed isolation method - Google Patents

Abstract

FIELD: oil and gas industry, particularly oil and gas well construction.

SUBSTANCE: method for bed isolation by installing water-repellent screen at bottom water-oil bed contact involves lowering casing pipe in hole and cementing thereof; injecting hydrophobic polymeric plugging composition in water-bearing bed and in hole annuity through casing pipe orifices, wherein casing pipe to be lowered in hole is provided with side drillable magnesium plugs; drilling magnesium plugs; injecting oil buffer agent in hole; installing water-repellent screen at bottom water-oil bed contact by supplying hydrophobic polymeric plugging composition in portions. The second portion of the hydrophobic polymeric plugging composition includes hydrophobic hardening filler, namely dry cement. Then cement mortar is injected in hole and forced up to casing pipe orifices location to seal above orifices with cement cup.

EFFECT: increased simplicity and operational reliability.

1 tbl, 3 dwg

Description

The invention relates to the oil and gas industry and relates to the field of construction of oil and gas wells, in particular the isolation of aquifers in the development of oil fields.

A known method of isolating formations and channels in the annulus in the interval of the productive stratum before lowering the casing string, for example, a method of isolating formations (a.s. the initial pressure gradient, and before the filler is washed into the reservoir, water and clay solution are sequentially and continuously pumped under pressure not lower than the initial pressure gradient.

However, it has disadvantages. In an open trunk, it is difficult to separate the aquifer from the productive even with the installation of a packer. Often this cannot be done because productive ones are located below the aquifer. The isolation of aquifers in these cases leads to a deterioration in the productivity of the underlying oil strata.

In addition, the isolation of the aquifer in the reservoir is difficult due to the fact that it is opened on a clay solution. When used on the surface of a permeable formation, a filter cake forms. The grouting mixture through it, as a rule, fails due to high pressure. Exceeding it often leads to hydraulic fracturing without positive results on the isolation of an aquifer.

In the source (Amirov A.D., Karapetov K.A., Lemberansky F.D. et al., "A Reference Book on the Current and Overhaul of Oil and Gas Wells", M., Nedra, 1979, pp. 240, 6 the first paragraph), it is noted that to prevent the breakdown of plantar water "it is advisable to pump cement mortar under pressure through specially shot holes in the production string in the interval of oil-water contact."

The disadvantage of this method: upon contact with porous rocks from the cement mortar, water is filtered off, as a result of which the penetration of cement into the depth does not occur.

The closest technical solution to the proposed method is a method of isolating aquifers in the well with the installation of a hydrophobic screen, including lowering the casing into the well, cementing it, pumping through the holes in the casing of a hydrophobic polymer cement composition into the aquifer and into the annulus (RU No. 2180392 March 10, 2002).

The objective of the invention is the exclusion of flow of formation water through the annulus by ensuring the filling of the aquifer and channels in the annulus with grouting material that is resistant to the effects of formation water at extremely long distances from the well.

The problem is achieved due to the fact that in the method of isolating the aquifer in the well with the installation of a hydrophobic screen on the oil-water contact of the oil reservoir with bottom water, including the descent of the casing with drilled side magnesium plugs installed in the pipes, the casing is cemented , drilling plugs and pumping through the holes into the aquifer and into the annulus of the polymer composition, while the hydrophobic polymer oil buffer is pumped grouting composition (GPTS) in the form of two portions, and a hydrophilic curable filler is introduced into the second portion — an occlusion powder material that cures upon contact with water, for example, dry cement, and then cement grout is pumped after the GPTS and extruded to the interval of hole placement in the casing column after drilling side magnesium plugs and covers the interval of perforation with a cement cup.

All this shows the presence of a causal relationship between the totality of the features of the claims and the technical result. This proves the materiality of the features of the claims.

Due to the fact that the set of features characterizing the stated invention is not known from this area, it can be concluded that the claimed invention meets the condition of “novelty”

From the above it follows that the invention meets the condition of "inventive step", as it is not obvious to a specialist in this industry.

The invention is illustrated in the drawing, which presents a process diagram of the isolation of an aquifer using GPTS.

In drawing A - well after cementing the casing,

In drawing B - after cutting side magnesium plugs during the injection through the tubing of oil, GPTS and cement mortar,

In drawing B, the well is prepared for perforation of the oil reservoir (plugs are blocked by cement mortar, and the aquifer is blocked by a screen from the GPTS).

The flow diagram of the isolation of an aquifer using GPTS includes oil 1 and aquifer 2 layers, casing 3, side magnesium plugs 4, tubing 5, oil 6, GPTS 7 and cement slurry 8.

GPTS has the following composition, weight. hours:

Prepolymer FP-65-2  one hundred Hydrocarbon fluid 50-100 Water  2-3 Filler 1-10 Curing Accelerator UP-606/2  0.1-0.2

The grouting composition of the GPTS is hydrophobic. FP-65-2 is produced according to TU-38.403.548-87. Complex hardener: water and UP-606/2 are introduced into the composition on the surface, before injection into the well.

Important for GPTS is that the main hardener of the composition is water. UP-606/2 only reduces the hardening time. In hardened form, GPTS does not interact with oil.

Being pumped into the aquifer and into the channels of the annulus, the composition upon contact with the formation water immediately gives it additional thickening, and then passes into a rubber-like state. In order to ensure deep penetration of the composition into the formation and prevent its premature thickening, a buffer of oil is pumped into the well before the injection of the GTS. It eliminates the contact of the GPTS with water and reduces the filtration resistance to the penetration of the composition into the reservoir.

The penetrating ability of the GPTS is high. The results of the effect of GPTS on the permeability of natural cores are given in the table.

Initial permeability Interval in depth of insulating layer, mm Permeability corresponding to insulating layers, MD thirty 0-15 <2 15-30 <2 30-45 <2 45-60 <2

In more detail, the essence of the proposed method is described by an example of a specific implementation.

In field conditions, the method is carried out according to the following scheme.

After the casing 3 is lowered into the well and the borehole formation (waiting for cement to harden), a milling cutter or bit is lowered into it on tubing 5 (tubing). With its help, lateral magnesium plugs 4 are cut off and holes are opened in these places, communicating the tube space with the annular, in particular, with the aquifer 2.

Through the tubing 5, oil 6 and GPTS 7 are pumped into this interval.

GPTS 7 is pumped using the CA-320 pump. For this, the mixture of GPTS 7 from the barrels is poured into the grouting chunk and only then is pumped into the tubing 5.

When filling the chunk with the second portion of GPTS 7, filler is introduced under the stream - dry cement - and the mixture is pumped into the well.

After the completion of injection of GPTS 7, without interrupting the process, cement is injected into the well to install the bridge in the interval where the side magnesium plugs were drilled 4. Then the casing 3 is perforated opposite the oil reservoir 1, the well is put into operation and put into operation.

The technical result is the creation of an easy-to-use, reliable in operation and cheap way to isolate an aquifer before perforation and further operation of the oil reservoir.

The advantage of the proposed method over the known is that it provides:

- high-quality insulating work by eliminating the decomposition of insulating material in contact with formation water, cement, rock, curing directly with the rock saturated with water, including inside it and in the annular channels, because water is its main hardener;

- increasing the productivity of wells by achieving hydraulic perfection of the productive part of the well, since the deep penetration of the GTS ensures the creation of a screen of the largest diameter in oil-water contact between oil and bottom water;

- acceleration of the well development process;

- reduction of water cut in the period of long-term operation of the wells by ensuring the tightness and reliability of separation and fastening of the reservoirs.

This allows us to argue that this technical solution meets the "criteria" of the invention, and therefore is subject to protection by the title of the inventive right according to the authors.

Claims (1)

A method of isolating aquifers in a well with installing a hydrophobic shield, including lowering the casing into the well, cementing it, injecting a hydrophobic polymer cement composition through the holes in the casing into the aquifer and into the annulus, characterized in that the casing is lowered with drilled side magnesium magnets plugs, after drilling of which a buffer of oil is pumped into the well, a hydrophobic screen is installed at the water-oil contact of the oil reservoir with bottom water, d For this purpose, a hydrophobic polymer grouting composition is pumped in portions, while a hydrophilic curable filler, dry cement, is introduced into the second portion, then cement mortar is pumped, which is pressed to the interval of the holes in the casing to be covered with a cement glass.