The way of the development of oil deposits in carbonate reservoirs

 

(57) Abstract:

The inventive method consists in drilling oil wells by a system of vertical and horizontal wells and the creation of cavities drives multiple hydrochloric acid baths. Caverns drives create in horizontal wells: first of all, at the ends of the horizontal boreholes tightening row, all subsequent consistently in the middle of the trunk, then at the beginning of the barrel and finally between adjacent cavities drives. Each subsequent cavern drive create, after reducing the flow rate in the previous cavern storage to the initial value. 1 Il., table 1.

The invention relates to the development of oil fields, presents carbonate reservoirs.

There is a method of developing oil fields by drilling vertical and horizontal wells (1). The disadvantage of this method is the low rate of oil recovery of layers, due to low sweep flooding.

The closest in technical essence to the present invention is a method of developing oil deposits in carbonate reservoirs producing and injection wells with the creation of Ogorodnik hydrochloric acid baths [2]

In terms of carbonate reservoirs with high-viscosity oil efficiency way up to 2-3 meals a day to increase production rate. Especially effective is the use of it compared to the simple hydrochloric acid treatment in conditions of massive deposits, where there is the possibility of rapid irrigation wells after treatments.

A significant disadvantage of this method is that intermittent heterogeneous reservoirs achieved low sweep flooding. In these conditions acceptable oil recovery is achieved only when a dense grid of wells, which is costly and not always feasible from an economic point of view. In addition, the disadvantage is the short duration of effect.

The aim of the invention is to increase the oil recovery factor, increasing the productivity of wells and the duration of the effect processing bottom-hole zones (OPZ) by increasing the sweep flooding and improve the opening of the seams.

This goal is achieved by a method including the drilling of an oil reservoir system of vertical and horizontal wells and creation of cavities drives mnogokratnyh wells, especially at the ends of the horizontal boreholes tightening row, and all subsequent consistently in the middle of the trunk, then at the beginning of the barrel and finally between adjacent cavities drives, and each subsequent cavern drive create, after reducing the flow rate in the previous cavern storage to the initial value.

The drawing shows the layout of the wells and the location of the caverns drives in horizontal wells drilled along the proposed method.

The method is carried out in the following sequence.

The implementation of the method, consider the example plot shown in the drawing. Oil reservoir, presents a mixed discontinuous reservoirs, razvarivat system of vertical and horizontal wells. Exercise OPZ vertical and horizontal wells with multiple hydrochloric acid baths. First SCR is carried out in the wells tightening row (second row). Then, in the wells of the first and third rows. The sequence in which the conducting SCR in the wells shown in the drawing) 1 5. According to the method first handle end portion of the horizontal wellbore (point 1). This allows first of all to work out, turn it out of the development, thereby maintaining in working condition, the other end of the horizontal shaft. Depending on the thickness of the layer volume of 12% hydrochloric acid for one of the bath ranges from 3 to 13 m3.

The IPF procedure is as follows. Download solution of hydrochloric acid into the well with a minimum wellhead pressure (0.1-0.5 MPa). After the reagent of the processed interval of the borehole leave to react for 2-3 days. Then the well is washed to extract the reaction products. Thus SCR repeat 3-5 times. As a result, in the treated interval increases the diameter of the hole that leads to increased productivity. The effect of the SCR continues 5-12 months, after which there is a need to re SCR. This time the SCR is conducted according to the same technology, but at half the distance from the end of the horizontal wellbore. This allows you to develop a higher level this area, and subsequent flooding to disable it, while retaining to develop the rest of the horizontal wellbore. After effect from the next IPF procedure is repeated again in the interval of the beginning of the horizontal wellbore, and later between the zones in which the crystals are evenly distributed along the horizontal bore: in the beginning in the end, in the middle and at intervals equally spaced, thus creating a uniform grid zones of high productivity.

The next stage of the application of the method is the creation of cavities storage wells I and III series. All this allows to create a network of highly productive intervals, which is almost equivalent to seal the well grid. This leads to an increase of the sweep flooding, therefore, to increase oil recovery, in addition, increase the production wells, the intensity of development.

The proposed method was tested on a plot of oil deposits shown in the drawing. The results of benchmarking the development of known and proposed methods are presented in the table. The figures show that the application of the proposed method, the recovery factor increased from 0.25 to 0.30, the production wells increased from 10 to 20 t/day. thereby decreased the lifetime of the site. On average area per year will be produced to 5.8 thousand tons of additional oil.

The WAY of the development of OIL DEPOSITS IN CARBONATE RESERVOIRS, including the drilling of its system of vertical and horizontal wells and creation of cavities drives mekonah, moreover, in the first place - at the ends of the horizontal boreholes tightening of a number, and all subsequent caverns-drives - consistently in the middle of the trunk, then at the beginning of the barrel and, finally, between adjacent cavities drives, and each subsequent cavern drive create, after reducing the flow rate in the previous cavern storage to the initial value.

 

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25 cl, 1 tbl, 3 ex

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2 cl, 2 tbl, 2 ex

FIELD: oil and gas production.

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EFFECT: increased oil production, prolonged overhaul period, improved environmental safety, and lowered production expenses.

2 tbl, 3 ex

FIELD: oil and gas extractive industry.

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2 cl, 3 ex, 6 tbl, 2 dwg

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SUBSTANCE: method includes placing water solution of carnallite ore, either modified, concentrated, or mixtures thereof, said solution is used at maximal for well temperature conditions concentration and is pumped in amount, necessary and enough for forming a hydraulic column in well shaft above ceiling of productive bed and along remaining shaft height well is filled with water up to mouth. Carnallite ore used has composition, in percents of mass: potassium chloride 20.5-21.5; sodium chloride 19.5-22.5; magnesium chloride 24.0-27.0; crystallization water 29.5-30.5. Modified ore has composition, in percents of mass: potassium chloride 23.0-29.5; magnesium chloride 31.8-46.0; crystallization water - the rest. Said water solution is prepared by dissolving ore in fresh technical water, drained from oil preparation plants, or in bed water. In case of dissolving in bed water, the latter is pumped from well at temperature 60-90C. During perforation of well, value of technological liquid hydraulic column above productive bed ceiling is taken equal to (1.03-1.07)-(1.05-1.1)Pb, where Pb - productive bed pressure. Water solution of carnallite ore is used at density 1.23-1.37 t/m3. During use of said solution as working body of force wells it is used at density 1.05-1.20 t/m3, and solution also contains swelling inhibitor for argillaceous component of oil and gas bearing bed, like oxyethylenedendiphosphone acid, in amount 0.05-0.15% of used dissolved ore mass.

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2 tbl, 2 ex

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