RU2121567C1 - Method of completion of well with formation fluid level below tubing shoe under conditions of abnormally low formation pressures - Google Patents

Abstract

FIELD: development of gas and gas-condensate fields at the final stage of well operation; may be used in completion of well with high stage of gas presence (300-500 m). SUBSTANCE: method includes injection into well of anionic or nonionic surfactant or their mixture in the amount sufficient for formation of stable foam of formation fluid. Well is closed and excessive pressure is built up at wellhead meeting the conditions specified in the invention description. Introduced into pipe space successively are gas-forming agent, for instance, ammonium carbonate and acid, for instance, 24-% hydrochloric acid solution in stoichiometric quantities. Annular space is communicated with high-pressure gas main line, and pipe space is connected with flare line up to ceasing of foam flowing out. Efficiency of removal of formation fluid from self-killing wells is increased due to water encroachment under conditions of abnormally low formation pressures (below 0.5 of hydrostatic pressure) when formation fluid level is below tubing shoe and tubings are above interval of perforation of producing formation. EFFECT: higher efficiency.

Description

 The invention relates to the development of gas and gas condensate fields in the final stages of operation, and is intended for the development of wells with a large gas-bearing floor.

Analysis of the existing level showed the following:
There is a known method of developing a well by replacing the fluid filling the well with a solution of a surface-active substance (surfactant) and a blowing agent, such as ammonium carbonate, followed by aeration (see A.S.N 691557 from 04.04.78 according to class E 21 B 43 / 00, OB N 38, 1979).

 The disadvantage of this method is the inability to remove the formation fluid from the self-stagnant due to watering the well under conditions of abnormal low formation pressure (AAP), when the tubing is above the perforation interval of the reservoir, and the level of formation fluid is below the tubing shoe.

 There is a method of developing a well by replacing the borehole fluid with water in two cycles, in the first of which water is pumped into the annulus in the amount of not less than the volume of the lifting pipes with the addition of a reagent capable of decomposing under formation conditions with the formation of gases, for example ammonium carbonate, and in the second - water injection in a volume not exceeding the annular space of the well with subsequent commissioning of the well through a column of lifting pipes (see A.S.N 1767163 from 04.01.90 according to class E 21 B 43/25, OB N 37 , 1992).

 The disadvantage of this method is the inability to remove formation fluid from self-stagnant due to flooding of the well under the conditions of AIP, when the tubing is above the perforation interval of the reservoir, and the level of reservoir fluid is below the tubing shoe. In addition, in the process of replacing a clay solution with water containing a blowing agent, the latter warms up slowly due to the use of cold water and the gas evolution rate may be insignificant, and the process occurs in parts from the surface. The conditions for decomposition of the blowing agent will arise only when the hydrostatic pressure of the clay solution is less than the saturation pressure for the evolved gas at the reached heating temperature. In the known method there is no operation for the introduction of surfactants. The technological process boils down to gas bubbling through a liquid layer, and not to foaming, which reduces the efficiency of liquid removal. After water injection (second cycle), when water with a blowing agent approaches the tubing shoe, the maximum pressure of water injection is noted, which can lead to absorption of water with a blowing agent into the reservoir and further reduce the permeability of the bottomhole zone and decrease the amount of blowing agent involved in the process of formation fluid removal .

The technical result that can be obtained by implementing the present invention is as follows: the efficiency of the removal of formation fluid from self-stagnant due to flooding of wells with a large gas-bearing floor (300-500 m) under conditions of abnormally low formation pressures (below 0.5 P _hydrost ) _increases when the level of reservoir fluid is below the tubing shoe, and the latter is above the perforation interval of the reservoir.

где
P_у - давление на устье скважины, МПа;

- давление насыщения для углекислого газа при температуре, t, для конкретной скважины в интервале нахождения столба воды, МПа;
P_пл - пластовое давление, МПа;
K - эмпирический коэффициент, определяемый по геолого-техническим данным для каждого месторождения, характеризующий репрессию на пласт, вызывающую поглощение, отн.ед.,
причем в трубное пространство последовательно вводят газообразователь и кислоту в стехиометрических количествах, соединяют затрубное пространство с магистралью газа высокого давления, а трубное пространство открывают на факельную линию до прекращения выхода пены.The technical result is achieved using the known method by introducing into the well a gasifier that emits carbon dioxide, in which surfactants are additionally pumped into the well in an amount sufficient to obtain stable foam from the formation fluid, the well is closed and excess pressure is created at the wellhead, which meets the following condition:

Where
P _y - pressure at the wellhead, MPa;

- saturation pressure for carbon dioxide at a temperature, t, for a particular well in the interval of finding a column of water, MPa;
P _PL - reservoir pressure, MPa;
K - empirical coefficient, determined by geological and technical data for each field, characterizing repression on the reservoir, causing absorption, rel.
moreover, a blowing agent and acid are sequentially introduced into the tube space in stoichiometric amounts, the annulus is connected to the high-pressure gas line, and the tube space is opened to the flare line until the foam exit ceases.

According to the operating conditions of fields with a large gas-bearing floor, in the initial period of development, wells are equipped with elevator pipes deflated to the upper holes of the production interval or above it, for example, Vuktylskoye gas condensate field (see Rassokhin G.V., Reitenbakh G.R., Tregub N.N. et al. Development of gas condensate fields with a large gas content floor. - M .: Nedra, 1984, pp. 105-107). This is done for reasons that when lowering the pipes to the lower holes, pressure losses during gas movement to the tubing shoe can reach significant values. With gas flow rates in the initial development period of the order of 800 thousand m ³ / day, pressure losses during gas movement from overlying horizons to the tubing shoe can be from 2.5 to 10.0 MPa per 500 m of the filter part of the barrel.

 As the field is developed, formation pressure drops, formation water begins to flow into the wellbore, gas production rates decrease and become insufficient for the removal of formation water, which accumulates at the bottom of the well. As a result, the conditions are created when the self-squeezing of the well occurs and the well stops, while the zone located below the shoe essentially turns into a "dead" zone.

 Removing the "dead" columns of formation fluid from the well is possible by lowering the tubing under the fluid level to the maximum possible depth so that the tubing shoe is located in the interval of the lower gas horizons. To carry out such a descent, in accordance with the current rules, it is necessary to shut off the well, raise the tubing, produce from an audit, lower the tubing to the required depth again and master the well using one of the known methods. Obviously, this option is time-consuming and does not guarantee a gas inflow after carrying out these works as a result of contamination of the bottom-hole zone.

 The problem of removing fluid from the "dead" space of the well can be solved by lowering into the tubing string of flexible pipes with a diameter of 19 - 32 mm, wound on a drum, and displacing the fluid from the well with foam systems. However, such installations with flexible pipes are only being developed in domestic practice, and in such cases it is necessary to buy foreign equipment. There is also a method of installing the liner on the bottom through the tubing string, which can be used to remove fluid from the bottom of the wells and flush sand and clay plugs (see Kondrat R.N. et al. Removing fluid from the bottom of gas wells. Express information, ser .: Technology, drilling and development of gas fields. M.: VNIIEgazprom, 1976, N 15, pp. 10 - 14, A.S. N 1211408 from 04.10.82 according to class E 21 B 43/00, OB N 6, 1986). However, basically, the wells were initially not equipped to perform work with the help of a tool lowered into the tubing string on a cable. To carry out these operations, additional equipment is required: a packer, a landing nipple, a circulation valve, and also a number of technological specifications must be taken into account and the Safety Rules in the Oil and Gas Industry 1993 must be observed.

 Technical solutions are also known: a device for removing fluid from the bottom of gas wells, represented by strips of fibrous capillary-porous material placed on the inner surface of the tubing with ends immersed in the borehole fluid (see A.S. N 848599 from 09/26/79, cl E 21 B 43/00, publ. OB N 27, 1981). This technical solution is applicable only for working wells, because tape material is blown through the gas stream from the formation, which contributes to the evaporation of the liquid; a method for developing a well with equipment at the bottom of the production casing with light-alloy aluminum pipes and pumping caustic soda solution through them (see AS No. 1002534 of 05/07/81 for class E 21 B 43/00, published in OB N 9, 1983 .). In this case, a low rate of hydrogen evolution is observed, and dissolution occurs at the site of contact of the pipe with caustic (from the pipe surface), which is ineffective.

 Known methods for removing fluid from the well by pumping a mixture of surfactants with a gas-emitting agent and hydrochloric acid (see A.S. N 829883 from 07.25.79, class E 21 B 43/25, publ. OB N 18, 1981; and S. S. N 1609976 from 12.28.84 according to class E 21 B 43/25, publ. OB N 44, 1990); There are known methods for removing liquid, where a gaseous working agent is injected into the riser (see A.S. N 629327 of 09/26/75, class E 21 B 43/00, publ. OB N 39, 1978; Muravyov I.M. . and others. Technology and equipment for oil and gas production. M: Nedra, 1971, p. 260-262).

 No technological operations have been identified to create excess pressure at the mouth according to the claimed mathematical inequality in conjunction with the above, which creates a new effect - ensures the removal of formation fluid from the "dead" zones. The claimed technical solution has an inventive step.

 Surfactants are pumped according to the claimed technology, both anionic and nonionic, or mixtures thereof.

 A large number of blowing agents are known, which are various chemical substances capable of generating gas under conditions of a well due to decomposition or chemical interaction.

 For the most effective removal of fluid, it is necessary that gas generation occurs throughout the entire volume of the fluid, and not only in its upper part, which usually happens if the tubing does not reach the level of the borehole fluid.

In addition, gas evolution should occur as much as possible with a high gas flow rate. The fact is that for the same amount of gas released, V _g , an increase in the flow rate of the obtained gas q _g = V _g / t is decisive for the liquid removal process, since at a low gas evolution rate all gas can simply sparge through the liquid layer without carrying out the work of taking it out.

 As a gasifier, emitting carbon dioxide and meeting the above conditions, you can take, for example, carbon ammonium salt.

The choice of carbonic ammonium salt as a blowing agent is due to the fact that the solubility of carbon dioxide in water increases sharply with increasing pressure, and when the pressure drops below the saturation pressure, CO ₂ is released in gaseous form. At the same time, at pressures up to 50.0 MPa, aqueous solutions of CO ₂ approximately obey Henry's law.

Carbon ammonium salt is the most affordable gasifier that emits carbon dioxide. A commercial product is a mixture consisting mainly of ammonium bicarbonate NH ₄ HCO ₃ and some amounts of ammonium carbonate (NH ₄ ) ₂ CO ₃ and ammonium carbamate NH ₄ COONH ₄ . Moreover, during storage of the salt, the proportion of bicarbonate in it increases due to the hydrolysis of ammonium carbonate proceeding in the presence of traces of moisture
(NH ₄ ) ₂ CO ₃ + H ₂ O ---> NH ₄ HCO ₃ + NH ₂ COONH ₄ + NH ₄ OH
In the future, to simplify the calculation, we assume that the entire carbon ammonium salt consists of ammonium bicarbonate.

рассчитывают

по следующей формуле

где

коэффициент фазового равновесия, зависящий от температуры, определяемый из справочника; x - молярная доля CO₂.Providing overpressure at the wellhead that meets the condition

expect

according to the following formula

Where

coefficient of phase equilibrium, depending on the temperature, determined from the directory; x is the molar fraction of CO ₂ .

The molar fraction of CO _{2 is} calculated based on the amount of carbon dioxide released during the interaction of ammonium bicarbonate with alkaline earth metal chlorides present in the formation water and the total volume of water in the well.

2NH ₄ HCO ₃ + MeCl ₂ ---> 2NH ₂ Cl + MeCO ₃ + CO ₂ + H ₂ O,
Where
Me = Ca ²⁺ , Mg ²⁺ .

If the pressure P _y is less than the saturation pressure, then after the introduction of carbon ammonium salt into the well, carbon dioxide evolution will begin immediately after it contacts the formation water in the surface layer, as a result of which foaming and liquid removal will be ineffective.

 The empirical coefficient, K is the coefficient determined for each field at different stages of development, showing how many times the pressure in the well should exceed the reservoir pressure in order to cause fluid absorption. It depends on the thickness of the reservoir, its drainage, reservoir pressure, type of reservoir (granular, fractured), permeability of the reservoir, etc. It is determined for each field at different stages of development.

When P _y > P _PL (1 + K), the wellbore fluid is absorbed and, as a result, bottomhole zone is contaminated.

When P _y <P _PL (1 + K) absorption does not occur, the normal course of the claimed process is ensured. Mixed with produced water, the carbon ammonium salt interacts with the calcium and magnesium chlorides present in it.
2NH ₄ HCO ₃ + CaCl ₂ ---> 2NH ₄ Cl + CaCO ₃ + H ₂ O + CO ₂
2NH ₄ HCO ₃ + MgCl ₂ ---> 2NH ₄ Cl + MgCO ₃ + H ₂ O + CO ₂ .

But since the pressure in the well exceeds the saturation pressure, CO ₂ does not stand out in its free form, but dissolves in water, distributed throughout the entire volume of the liquid column.

During the reaction of produced water with a carbon ammonium salt, calcium carbonate and magnesium carbonate are formed. To dissolve them and obtain an additional amount of carbon dioxide, acid is introduced into the well in an amount equivalent to the difference between the carbon ammonium salt loaded into the well and its stoichiometric amount necessary for the reaction with formation water salts. In this case, reactions occur between the acid and calcium carbonates, magnesium, as well as an excess of carbon ammonium salt
CaCO ₃ + 2HCl ---> CaCl ₂ + H ₂ O + CO ₂
MgCO ₃ + 2HCl ---> MgCl ₂ + H ₂ O + CO ₂
NH ₄ NO ₃ + HCl ---> NH ₄ Cl + H ₂ O + CO ₂ .

углекислый газ, находившийся до этого в растворенном виде, переходит в газообразное состояние, энергично вспенивает скважинную жидкость и благодаря присутствию ПАВ образует устойчивую пену, по объему многократно превосходящую исходную жидкость. Увеличившаяся по объему, по сравнению с исходной жидкостью, пена достигает башмака НКТ, где захватывается газом, поступающим через затрубное пространство из шлейфа, и выносится через трубное пространство на поверхность. По мере выноса скважинной жидкости в виде пены, давление на нижележащие горизонты падает и они вступают в работу. Продувка скважины газом продолжается и до прекращения выноса следов пены из скважины. После этого скважина закрывается "на факел" и газ поступает в шлейф.Immediately after acid injection, the well is connected through the annulus to the loop of neighboring wells, and the tube space is opened. Well pressure drops rapidly and as soon as it gets lower

carbon dioxide, which was previously dissolved, goes into a gaseous state, vigorously foams the wellbore fluid and, due to the presence of surfactants, forms a stable foam that is many times larger than the original fluid. The foam, which has increased in volume compared with the initial liquid, reaches the tubing shoe, where it is captured by the gas entering the annulus through the annulus from the plume and is carried out through the tube space to the surface. As the wellbore fluid is removed in the form of foam, the pressure on the underlying horizons drops and they come into operation. Gas purging continues until the removal of traces of foam from the well ceases. After that, the well closes "on a torch" and gas enters the loop.

 In more detail, the essence of the proposed method is described by the following example.

 Example.

 Well depth - 3360 m.

 The perforation interval is 3250 - 2800 m.

 2.5 '' tubing lowered to a depth of 2800 m.

 The 5 '' production casing was lowered to a depth of 3360 m.

 Artificial Slaughter 3300 m.

The reservoir temperature at a depth of 2800 m - 50 ^o C.

 The well filter is filled with fluid to a depth of 2850 m.

 The reservoir pressure at a depth of 3250 m is 4.0 MPa.

Produced water of calcium chloride type with a density = 1200 kg / m ³ .

 The pressure created by the column of produced water at a depth of 3250 m is 4.8 MPa.

The volume of the well filled with produced water to the lower holes of the perforation interval is (3250-2850) x 12.5 = 5000 l = 5 m ³ , where 12.5 l is the volume of 1 running meter of the column with a diameter of 5 ''.

 The amount of reagents required for the process of removing fluid from the "dead" space of the well is determined.

Practice and laboratory studies show that for foaming 1 m ³ liquid, 300 kg of carbon ammonium salt, as well as 50 kg of KSSB and 3 kg (in terms of the active substance) of OP-10 are enough. Then, for processing 5 m ^{3 of} well fluid, respectively: 1,500 kg of salt, 250 kg of KSSB and 15 kg of OP-10 are required.

 It is advisable to add surfactants together. To do this, prepare 1667 kg of a 15% aqueous solution of KSSB and add 15 kg of OP-10 to it.

 The aqueous surfactant solution thus prepared is pumped into the borehole space, having previously been blown through the flare line with gas from neighboring wells.

при температуре скважинной жидкости (50^oC). Для этого рассмотрим, что произойдет после добавления углеаммонийной соли в скважину. По результатам анализа пластовая вода, находящаяся в скважине, содержит 15,83 г/л Ca⁺⁺ (43,84 г/л CaCl₂) и 6,37 г/л Mg⁺⁺ (24,95 г/л MgCl₂). Соответственно в 5000 л пластовой воды содержится 219,2 кг CaCl₂ и 124,75 кг MgCl₂.Determine the pressure that must be created at the wellhead so that carbon dioxide is in a dissolved state

at the temperature of the borehole fluid (50 ^o C). To do this, consider what will happen after adding carbon ammonium salt to the well. According to the analysis, produced water in the well contains 15.83 g / l Ca ⁺⁺ (43.84 g / l CaCl ₂ ) and 6.37 g / l Mg ⁺⁺ (24.95 g / l MgCl ₂ ) . Accordingly, in 5000 l of produced water contains 219.2 kg of CaCl ₂ and 124.75 kg of MgCl ₂ .

When carbon ammonium salt is added to the well, it reacts with calcium and magnesium chlorides to produce carbon dioxide and form calcium and magnesium carbonates
CaCl ₂ + 2NH ₄ HCO ₃ ---> 2NH ₄ Cl + CaCO ₃ + CO ₂ + H ₂ O (1)
MgCl ₂ + 2NH ₄ HCO ₃ ---> 2NH ₄ Cl + MgCO ₃ + CO ₂ + H ₂ O (2)
According to the first reaction, 197.68 kg of calcium carbonate is formed and 44.24 m ³ (90.86 kg) of carbon dioxide is released. The consumption of ammonium carbonate in this reaction is 312.28 kg.

According to the second reaction, 110.47 kg of magnesium carbonate is formed and 29.35 m ³ (60.28 kg) of carbon dioxide is released. The consumption of carbon ammonium salt in this case is 207.16 kg.

The total amount of carbon dioxide released in two reactions is 73.59 m ³ (151.14 kg). This volume of gas must be in a dissolved state, for which it is necessary to create a pressure greater than the saturation pressure for CO ₂ at a given temperature (50 ^o C).

Молярная доля углекислого газа, растворенного в воде, находящейся в скважине, равна

где
151140 - масса CO₂ в г;
46,0055 - г-моль CO₂;
6417000 - масса воды в г;
18,01528 - г-моль воды.250 kg of KSSB is administered in the form of a 15% aqueous solution in which the proportion of water is 1417 kg. Thus, the total volume of water in the well becomes equal
5000 + 1417 = 6417 l
At a temperature of 50 ^o C the constant of phase equilibrium of carbon dioxide in water is

The molar fraction of carbon dioxide dissolved in the water in the well is

Where
151140 - mass of CO ₂ in g;
46.0055 g-mol of CO ₂ ;
6417000 - mass of water in g;
18.01528 - g mole of water.

После взаимодействия с пластовой водой образуются 197,68 кг углекислого кальция, 110,47 кг углекислого магния и остаются непрореагировавшими 1500 - 312,28 - 207,16 = 980,56 кг углеаммонийной соли.The saturation pressure necessary for complete dissolution at 50 ^o C of 151.14 kg (73.59 m ³ ) of carbon dioxide in 6417 kg of water will be equal

After interaction with produced water, 197.68 kg of calcium carbonate, 110.47 kg of magnesium carbonate are formed and remain unreacted 1500 - 312.28 - 207.16 = 980.56 kg of ammonium carbonate.

 The amount of hydrochloric acid to be added to the well is determined.

To dissolve 197.68 kg of calcium carbonate
CaCO ₃ + 2HCl ---> CaCl ₂ + CO ₂ + H ₂ O
600 kg of 24% hydrochloric acid are required, with 44.24 m ³ (90.86 kg) of carbon dioxide being released.

To dissolve 110.47 kg of magnesium carbonate
MgCO ₃ + 2HCl ---> MgCl ₂ + CO ₂ + H ₂ O
398 kg of 24% hydrochloric acid are required, with 29.35 m ³ (60.28 kg) of carbon dioxide being released.

For decomposition of 980.56 kg of previously unreacted carbon ammonium salt
NH ₄ HCO ₃ + 2HCl ---> NH ₄ Cl ₂ + CO ₂ + H ₂ O
1884 kg of 24% HCl are required, while another 277.83 m ³ (570.62 kg) of carbon dioxide is released.

The total amount of added 24% hydrochloric acid
600 + 398 + 1884 = 2882 kg,
and the total amount of carbon dioxide, which is obtained from 1500 kg of carbon ammonium salt
44.24 + 29.35 + 44.24 + 29.35 + 277.83 = 425 m ³
Thus, as a result of foaming of 6.4 m ³ liquids turn into volume foam
425 + 6.4 = 431.4 m ³ ,
that is, the foam multiplicity reaches 70 and above, which ensures the successful rise of the foam to the tubing shoe and its removal by a gas stream from the loop from the well.

Given that P _у should not exceed the liquid absorption pressure, the upper limit of the pressure that must be maintained should be determined
P _y <(1 + K) P _pl = (1 + K) • 4.0 MPa
The practice of work shows that the value of K is from 0.1 to 0.2. We take the average value of K = 0.15, then
P _y <(1 + 0.15) • 4.0 = 4.6 MPa
those. the value of P _y should be more than 2.58 MPa, but at the same time should not exceed 4.6 MPa.

Consider what pressure will be at a depth of 2850 m, if the pressure P _у = 2.6 MPa is created at the wellhead.

или

где
Р_з - забойное давление газа (т.е. на глубине 2850 м), МПа;
P_у - давление на головке скважины, МПа;

относительная плотность газа по воздуху;
L - глубина скважины, м;
Z_ср - коэффициент сверхсжимаемости газа, отн. ед.;
T_ср - средняя температура, K;
e - основание натурального логарифма.It is known that if the pressure of the stationary gas P _y , then the pressure at the bottom is
P _s = P _y • e ^s
Where

or

Where
P _s - bottomhole gas pressure (i.e., at a depth of 2850 m), MPa;
P _y - pressure at the wellhead, MPa;

relative density of gas in the air;
L is the depth of the well, m;
Z _cf - gas compressibility coefficient, rel. units;
T _cf - average temperature, K;
e is the base of the natural logarithm.

Z_ср=1; T_ср=303 K,
тогда

e^S = 1,2528
P_з = P₂₈₅₀=2,6 • 1,2528 = 3,26 МПа,
т.е. давление на глубине 2850 м будет больше

и меньше (1+КР)P_пл. Таким образом, принимаем P_у = 2,6 МПа.Application

Z _cf = 1; T _cf = 303 K,
then

e ^S = 1.2528
P _s = P ₂₈₅₀ = 2.6 • 1.2528 = 3.26 MPa,
those. pressure at a depth of 2850 m will be greater

and less (1 + KR) P _pl . Thus, we take P _y = 2.6 MPa.

 The process of well development is carried out as follows.

 The disconnected self-silenced well is flushed to the flare with gas from the plume until dry gas exits. 250 kg of dry KSSB are dissolved in 1417 liters of water, 15 kg of OP-10 are added to the solution, and the solution is pumped through the annulus into the well. After that, a pressure of 2.6 MPa is created at the wellhead. After creating the necessary wellhead pressure (2.6 MPa), the well closes and a lubricator is installed on it. Through a lubricator, 1500 kg of ammonium carbonate salt are introduced into the well. Since the pressure in the well is greater than the saturation pressure of carbon dioxide, it does not stand out in its free form, but completely dissolves in the well. After entering and dissolving the carbon ammonium salt, 2882 kg of 24% hydrochloric acid are pumped into the well and the annular space is immediately connected to the loop of neighboring wells, and the pipe space is opened. The pressure in the well decreases rapidly and, as soon as it becomes lower than the carbon dioxide saturation pressure, the latter, which is previously in a dissolved state, passes into a gaseous state, energetically foams the wellbore fluid and, thanks to the presence of surfactants, forms a stable foam that is many times larger than the initial fluid. Foam reaches the tubing shoe, where it is captured by the gas entering the annulus from the plume, and carried through the pipe space to the surface. As the wellbore fluid is removed in the form of foam, the pressure on the underlying horizons drops and they come into operation. Gas purging is continued until the removal of traces of foam from the well ceases. After that, the well closes "on a torch" and gas enters the loop.

 The inventive method is available, it does not require additional special technological equipment and for the first time effectively solves the problem of the removal of formation fluid located below the tubing shoe under the conditions of the API.

Claims (1)

A method of developing a well with a level of formation fluid below the shoe of the tubing under conditions of abnormally low formation pressure by introducing into the well a gasifier that emits carbon dioxide, characterized in that the surfactant is additionally pumped into the well in an amount sufficient to produce stable foam from formation fluid, close the well and create excess pressure on the wellhead, which meets the following condition:

where P _y - pressure at the wellhead, MPa;

saturation pressure for carbon dioxide at temperature t, for a particular well in the interval of finding a column of water, MPa;
P _PL - reservoir pressure, MPa;
K - empirical coefficient, determined by geological and technical data for each field, characterizing repression on the reservoir, causing absorption, rel.
moreover, a blowing agent and acid are sequentially introduced into the tube space in stoichiometric amounts, the annulus is connected to the high-pressure gas line, and the tube space is opened to the flare line until the foam exit ceases.