RU2427703C1 - Procedure for construction of wells of multi-pay oil field - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: procedure for construction of well of multi-pay oil field consists in drilling borehole to project depth with opening non-uniform pays of pashiysky horizon, in geo-physical survey, in lowering production string and in its cementing. Drilling is performed without opening a water-bearing section of the pay. At cementing the production string a stop-ring, a device for collar cementing, and a cementing back-throttle valve are located above the pay. Also, integrity of a clay bridge is kept intact between upper and lower pays.

EFFECT: prevention of annulus water flow into well, maintaining collector properties of multi-pay oil field, saving expenditures at construction of well.

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Description

The invention relates to the oil industry, in particular to the construction of oil and gas wells.

There is a method of well construction, in order to prevent water inflow from the lower aquifers, with limited face in two stages (Sereda N.G., Soloviev E.M. "Drilling of oil and gas wells." Moscow, Nedra, 1988, §12.2 , p. 233).

Two-stage construction of a well with production casing being put on the roof of the Pasha horizon with further drilling of the trunk along the productive part of a smaller diameter is associated with the risk of the absence of productive oil-bearing strata “a, b1” of the Pasha horizon. If this fact is revealed, further construction of the well as an intake or injection well is associated with additional costs in part - further deepening of the well with a smaller diameter bit and subsequent fastening of the section with a small diameter shank, which does not guarantee high quality of the annular space cement stone. The closest is the standard method of constructing a well of a multilayer oil field, in which the well is drilled to the design depth with the opening of heterogeneous formations of the Pashian horizon, and the elements of the bottom of the casing are located below the entire productive pack (Sereda N.G., Soloviev E.M. "Drilling oil and gas wells. "Moscow, Nedra, 1988, §12.8, p. 255," Fundamentals of technology for lowering casing strings into the well ").

The disadvantage is that the presence of aquifers that have reservoir pressure greater than the oil-bearing and improved reservoir properties of the reservoirs adversely affects the quality of cement fastening behind the casing of the well and, as a rule, is accompanied by a breakthrough of water through the annulus into the perforation interval.

One of the drawbacks of these methods of completing well construction is that both during cementing the production string and cementing the liner for the time required to drill the entire thickness of the Middle Devonian, the process of filtering the flushing fluid into the pores of the productive oil-saturated reservoir and clogging them. This leads to a deterioration in the hydrodynamic connection of the formation with the well, i.e. formation productivity decreases. This especially happens when the lower aquifers have a greater reservoir pressure than the oil one, and washing fluid with a higher density is used to open the productive section. In this case, excess pressure on the reservoir will be excessively high, which contributes to a more intense pollution of the reservoir.

The third disadvantage is that the reservoir is additionally contaminated with cement slurry, since the overpressure during cementing is much greater than during drilling.

The technical task of the invention is to prevent obtaining annular water inflow in the well, maintaining the reservoir properties of a multilayer field, saving costs during well construction.

The problem is solved in that in this method of constructing a well of a multilayer oil field, including drilling a well to the design depth with opening heterogeneous formations of the Pasha horizon, geophysical exploration, lowering the production string and cementing it, drilling without opening the aquifer of the section, and cementing the production string a stop ring, a lip-cementing device, a cementing check throttle valve are placed above the reservoir, when m does not violate the integrity of the clay web between the upper and lower layers.

Distinctive features of the invention is that the primary opening of only the oil-saturated part of the section is performed, and the bottom of the production column is arranged with the calculation of the installation of structural elements (stop ring, UMC, TsKOD) above the production interval. Bottom is a casing pipe with a length corresponding to the thickness of the production interval, or a filter is installed with shear plugs (FPD) or with acid-soluble plugs.

The method of constructing a well is as follows.

During the initial opening of a productive section, the wellbore is deepened by drilling using mudding at a lightweight drilling fluid with a specific gravity of γ = 1.08-1.10 g / cm ³ to the design depth, geophysical work is performed as part of the final logging. In the presence of the upper productive oil-saturated strata “a, b1” of the Pasha horizon, preparatory work is carried out to lower the casing string.

The layout of the bottom of the production casing is carried out in the following sequence: a drilled shoe is installed in the lower part; in the productive interval, a selective depression filter (FPD), a filter with acid-soluble plugs, or a casing pipe with a length corresponding to the power of the productive interval, designed for cumulative or mechanical (drilling, hydromechanical) perforation, are installed in it; then a throttle check valve TsKOD, a lip-cementing device (UMC), a stop ring are installed.

After lowering the production casing to the bottom, cementing of the annulus is performed according to the “Instructions for fastening wells of OAO Tatneft RD 153-39.0-525-07.

Thus, the installation of elements of the cementing unit of the casing string is performed above the reservoir. Such an arrangement of casing string structural elements during drilling allows for reliable support of the borehole wall, while drilling with limited bottomhole provides reliable isolation from breakthrough of water inflow from the lower layers.

In addition, this method allows the use of a washing liquid of lower density. Thus, it ensures minimal penetration of drilling fluid and cement mortar filtrates into the bottomhole zone due to the fact that during cementing the pumped cement slurry will fill the annulus above the casing string structural elements, as cuff cementing device (CMC) prevents the deposition of cement slurry in the zone of the intended perforation interval.

An autopsy with a limited bottom of the productive section, without violating the integrity of the clay bridge between heterogeneous formations, provides reliable isolation from water breakthrough from aquifers. If necessary, tooling elements, a cement cup and a casing shoe are drilled with a bit of a smaller diameter, and the bottom hole is deepened by 0.5 meters in order to increase the filtration area into the well. Secondary autopsy is performed in the interval of the reservoir, cased by production casing, depending on the adopted tooling element.

In the absence of oil-saturated productive formations “a, b1”, a decision is made to further deepen the wellbore without loss in diameter, or to abandon the drilled well and drill from the existing conductor, the second well to a changed design bottom-hole point.

An example of a specific implementation of the method. Figure 1 and figure 2 shows a diagram of the construction of the well. The following notation is used in the drawing: 1 - upper limestone, 2 - clay bridge, 3 - reservoir D1 "a", 4 - reservoir D1 "b1 + b2", 5 - reservoir D1 "b3", 6 - drilled trunk, 7 - production column, 8 - stop ring, 9 - UMTS, 10 - TsKOD, 11 - perforation interval (FPD), 12 - shoe, 13 - pipe-benchmark, 14 - open face.

An industrial test of this method was carried out at well No. 13675. We drilled a well with a diameter of 215.9 mm to the design depth of the absolute mark of 1,482.3 m. We conducted geophysical surveys. We determined the interval of the reservoir in the range of absolute marks - 1479, 9-1482 m. We lowered the casing with a diameter of 168 mm to the bottom. The assembly of the bottom casing assembly elements was carried out in the following sequence (from bottom to top): shoe on the bottom; 6-meter filter with hollow plugs (FPD); circulation windows with a butterfly valve (TsKOD); cuff cementing device (UMC); 10 meter casing pipe; stop ring; further to the mouth of the casing with a diameter of 168 mm Cemented casing in standard mode. Cement hardening is 48 hours. We drilled tooling elements, a cement bridge with a bit with a diameter of 143.9 mm and deepened the trunk by 0.3 m. We conducted geophysical studies to evaluate the quality of cementing. Secondary autopsy was performed in the mode of creating depression on the reservoir being opened by cutting hollow plugs.

As a result, the productivity of the well was 15–25% higher than the productivity of the neighboring wells of this section of the development of the oil reservoir, which indicates the preservation of reservoir properties of the formation, and received anhydrous products. Cost savings during well construction were 15%.

The application of the proposed method allows to obtain reliable isolation from water inflow from the lower aquifers, to save the reservoir properties of the formation and to save on costs during the construction of the well.

Claims (1)

A method of constructing a well of a multilayer oil field, including drilling a well to the design depth with opening heterogeneous formations of the Pasha horizon, geophysical exploration, lowering the production string and cementing it, characterized in that the drilling is performed without opening the aquifer of the section, and when cementing the production string, the groan-ring , cuff cementing device, cementing check throttle valve placed above the reservoir, while not violating t integrity of the clay bridge between the upper and lower layers.

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