The method of developing multilayer gas fields

 

(57) Abstract:

Usage: in the gas industry and can be used in the development of multilayer gas deposits. Provides reduction in capital expenditures for the drilling of the Deposit and increase gas production. The inventive method provide a bypass gas from the lower reservoir into the upper low-pressure reservoir with pressure adjustment. On bottom of the high pressure reservoir are drilling production wells. They are drilling in an amount to provide planned gas production from the field. The bypass gas from the high pressure reservoir perform one pre drilled wells in the reservoir top with the low reservoir pressure in closed wells in the mouth and to the equalization reservoir and downhole pressures in the range of opening of the low pressure reservoir. After equalization of pressure takes place simultaneously joint operation of the upper and lower layers in a single tubing string. In flooding of lower layer obwodnica well translate into operation the upper reservoir, 4 Il., table 1.

The invention relates to gas industry and can be used in the development of megaflash or more layers, operated separate grids wells unified land development and consolidation of the gas streams of different layers [1].

The disadvantages of this method are: the limitation of the planned withdrawal of gas from the Deposit and the transfer of production to the upper layer, which in General may be low-pressure, which leads to the early commissioning of DCS (booster station); the worst conditions of the deposits, because of the grid wells in the different layers are static, developed on the basis of initial information about the Geology of the reservoir; the necessity of filing of hydrate inhibitor in the plumes of wells drilled on the top of the low-temperature reservoir.

The closest technical solution to the proposed method is "a Method of developing multilayer gas or gas-condensate field, which includes the drilling of producing wells, the bypass gas from the lower reservoir with pressure regulation [2].

This method is that the Buryats operating the wells on the top of the object, taking it for the main object of development. To slow the water wells of the upper layer of the coop shall have a bypass gas from the lower productive formation in the interval GVK (gas contact) upper primary object. To pressure in the upper main object in the range of bypass in the field of GVK is not reduced, it is necessary to maintain the equality of the volumes extracted and return the fulfilled gas. Based on these considerations determine the number of relief wells. The development of the field begins immediately with the upper reservoir.

The disadvantages of this method are: 1) limiting production of gas from the top of the object of development, because it is necessary to maintain the equality of the volumes extracted and return the fulfilled gas, and the lower layer is not actively being developed; 2) the possible loss of gas when the bypass in the most permeable layers of the topmost object in the field of GVK; 3) increase in capital cost due to the increase of the wells on the top of the main object and separate their operation; 4) the necessity of filing of hydrate inhibitor in wells drilled on the top of low-pressure and low-temperature reservoir.

The technical result of the invention is to reduce the capital cost of drilling.

Required technical result is achieved in that in the method of developing multilayer gas fields, including drilling of production swainey production wells are drilled on the bottom of the high pressure reservoir in number, providing planned gas production from the field, and the bypass gas from the high pressure reservoir carried out in advance by a single drilled wells in the reservoir top with the low reservoir pressure in closed wells in the mouth and to the equalization reservoir and downhole pressures in the range of opening of the low-pressure reservoir, and then, after equalization of pressure takes place simultaneously joint operation of the upper and lower layers in a single tubing string, as in flooding of lower layer obwodnica well translate into operation the upper reservoir.

In Fig.1 shows a diagram of the proposed method in the first stage, pre-bypass gas; Fig.2 - scheme of the proposed method at the second stage operation of the project.

The method includes the bypass gas (see Fig.1) in layer 1, where the pressure PPL< PSubfrom layer 2, where RPL> PSubon a single tubing string 3, a pressure regulator 4, and at the same time the joint development (see Fig. 2) layer 1, where PPL> PSuband layer 2, where PPL> PSuba single Elevator column 3, a pressure regulator 4.

N is Nevskogo field, where curve 1 - annual production of gas from a low pressure reservoir, curve (2) the total annual gas production of the two layers.

In Fig. 4 shows the change of current reserves of gas and pore volume low-pressure reservoir in the process of bypass gas and development, where I trace the change of current stocks, curve II - watering reservoir.

The method is as follows. Are drilling wells on the bottom of the high pressure reservoir in an amount to provide planned gas production from the field (i.e., taking into account simultaneously the joint operation of reservoirs 1 and 2 (Fig.1) via the same Elevator column). Then perform the bypass gas using the pressure regulator 4 (Fig. 1) from the bottom to the top in the low-pressure reservoir in the closed wells in the mouth, i.e., the gas production in the period of the bypass is not produced until the equalization reservoir and downhole pressures in the low-pressure reservoir 1.

During bypass (from 2 to 5 years) spend the arrangement of Providence.

The second phase takes place simultaneously - the joint development of both layers through the same wells drilled previously on the lower horizon in a single tubing string.

,

where qsumtotal gas production from the field, billion m3/year; qn- extraction from the lower reservoir; qin- extraction of the upper low-pressure reservoir, which after bypass was also high.

In the prototype implements only gas production from a limited Fund of the relief wells, and the resources of the upper layer essentially temporarily preserved, resulting in limited gas production from the field as a whole.

With a full stage and bypass gas increases thermodynamic potential of the low-pressure reservoir 1 and most fully realized synergy of a multi-reservoir system.

Example. While exploration of the Bovanenkovo field were revealed among the other two reservoir gas deposits. The lower reservoir: depth of 1500 m, the reservoir pressure of 15.0 MPa, reservoir temperature plus 42.5oC. Main gas reserves are concentrated in the lower reservoir (reservoir), which constitute 2031 bn m3. The upper low-pressure reservoir: depth of 620 m, reservoir pressure of 6.8 MPa, reservoir temperature plus 16oC. the gas Reserves of the upper low-pressure reservoir are 870 billion m3.

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To implement the process on the lower reservoir drilled 327 production wells (see table). According to the proposed method during the first 5 years implemented a bypass gas from the lower reservoir to the roof on top of already drilled wells (see Fig.3 - hatched area). The total volume of gas coming amounted to $ 413.2 billion m3. In the period of bypass gas production is not carried out until the alignment hole and the reservoir pressure. The volume of the bypass gas is controlled by the pressure regulator 4 that is installed in the tubing string 3. In addition, additional monitoring of the bypass gas is at the mouth of wells known calculation method.

After the end of the bypass gas wells put into operation, and is carried out simultaneously - joint development of both layers one tubing string.

In the bypass gas conditions improve development top (Cenomanian) of the stratum associated with flooding, which provide a significant increase in the period of the invasion of water into the reservoir (see Fig.4 - the beginning of the invasion of water at 18-19 years of development).

The table presents the results of calculations of the process steam is m gas production in the amount of 115 billion m3/year implemented 327 operational wells, while for the selection of the same gas volume prototype will require production wells is almost two times more.

ABAC is entered by the proposed method for the 9th year from the beginning of the field.

The use of the proposed method of developing multilayer gas fields has in comparison with existing methods the following advantages: 1) the consolidation of strata in one hydrodynamically connected, self-regulating system increases its synergy; 2) in the pre-bypass gas from the high pressure reservoir into the reservoir lower reservoir pressure and subsequent joint operation of a single Elevator column is reduced wells by 30-50% depending on the initial gas reserves and reservoir properties reservoir; 3) in case of combining layers of low-pressure (less than 7.4 MPa) and high pressure (more than 7.4 MPa) increases the term natural pressure operation of the system; 4) at the same time-the joint operation of reservoirs with different temperature characteristics allows to obtain in some cases basicrate conditions perfo the ending conditions and watering reservoir system which are manifested primarily in the fact that initially watered with the underlying horizon, while promoting GVK overlying horizon far behind the promotion GVK underlying (by increasing the pore volume of the upper layer due to the flow of gas from the bottom). Thus, in the case of critical irrigation underlying aquifer obwodnica wells are transferred to the operation upstream.

Thus, the method allows to effectively develop the resources of both production facilities with significantly lower cost compared to existing methods of development at the present time.

Sources of information

1. Zakirov S. N. and other Design and development of gas fields. -M.: Nedra, 1974, S. 312.

2. Patent of the Russian Federation, 2034131, CL E 21 B 43/00, 30.04.95.

The method of developing multilayer gas fields, including drilling wells, the bypass gas from the lower reservoir into the upper low-pressure reservoir with pressure adjustment, wherein the production wells are drilled on the bottom of the high pressure reservoir and in an amount to provide planned gas production from the field, and the bypass gas naibolee low reservoir pressure in closed wells in the mouth and to the equalization reservoir and downhole pressures in the range of opening of the low-pressure reservoir, then, after equalization of pressure takes place simultaneously joint operation of the upper and lower layers in a single tubing string, as in flooding of lower layer obwodnica well translate into operation the upper reservoir.

 

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FIELD: oil and gas extractive industry.

SUBSTANCE: device has operation columns of upper and lower well zones, placed eccentrically one inside the other in upper zone of well, double airlift column, mounted in upper well zone, and double airlift column, connected to operation well of lower well zone, separation column, mounted coaxially to operation column of upper well zone, and cementation pipe. According to invention, in a well with significant power of non-productive zone it is equipped with additional separating column with cleaning channels for lowering drilling tool therein and drilling well to lower well zone with removal of drilling slurry by double airlift column of upper zone through cleaning channels. Additional separating column is combined coaxially with operation column of lower well zone and is rigidly fixed to separation column.

EFFECT: higher efficiency.

1 dwg, 3 cl

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