RU2217588C2 - Method establishing water-oil ratio in gas field - Google Patents

Abstract

FIELD: oil and gas industry, development of gas deposits. SUBSTANCE: method includes collection of bottom and condensation water removed from well, its separation from gas flow, its mixing in separator and determination of general mineralization of water. Bottom and condensation water removed from all wells of selection zone in gas field is collected. Then samples of separated and mixed bottom and condensation water are taken and their chemical analysis for general mineralization is conducted, on basis of analysis material balance of mineralization is found by solving of mathematical equation. After this specific amount of bottom water in gas field is calculated by formulas provided that condensation water under stratal conditions exists in the form of vapor. Later specific amount of condensation water in gas field is established. Thereupon total amount of bottom water and total amount of condensation water per day are determined. On basis of obtained data total amount of water in gas field per day is computed. So average specific amount of bottom and condensation water in gas field can be timely determined on basis of data of chemical analysis of water samples selected from inlet separators for general mineralization as well as total amount of water in gas field per day. EFFECT: increased accuracy and timeliness of establishment of water-oil ratio in gas field. 1 dwg, 1 tbl

Description

The invention relates to the field of oil and gas industry and can be used in the development of gas fields.

There is a method of determining the water factor according to the chemical analysis of water discharged from the well and calculating the amount of plantar, condensation and man-made water at each producing gas well [1. RF patent No. 2128280 of 03/27/99].

The disadvantage of this method is the need for fluid sampling at each well, which is accompanied by irretrievable gas losses and environmental pollution, conducting expensive chemical analyzes to determine the content of sodium, potassium and calcium ions. In addition, the definition of the water factor of the gas field as the algebraic sum of the water factors for each well gives a distorted result due to condensation and accumulation of water in the lowered sections of the gas collection network at low gas speeds and, conversely, due to the removal of water from these sites at high gas speeds. When summarizing the research results for each well, it is necessary to process large volumes of source data and bring them to the actual operating modes of the gas field.

A known method for determining the water factor of the gas field at the inlet separators by adjusting the level (discharge) of liquid from the separators, in which the liquid from all wells of the gas field is separated from the gas stream in the separators and accumulates in special containers, when the level of the mixture consisting of carbonated liquid and mechanical impurities of a certain size, discharge occurs, summing the number of discharges per day and knowing the volume of the reservoir, determine the water factor of the gas field [2. Gvozdev B.P., Gritsenko A.I., Kornilov A.E. Operation of gas and gas condensate fields. - M.: Nedra, 1988, p. 282].

The disadvantage of this method is insufficiently accurate methods of measuring the amount of water that is beaten off in the separators, since carbonated liquid and mechanical impurities accumulate in the tank. In addition, measuring the amount of water in the inlet separators is laborious and time consuming.

Currently, the main natural gas fields (Urengoyskoye, Yamburgskoye, Medvezhye, Komsomolskoye, Vyngapurovskoye) are exploited during the period of declining production, which is accompanied by the active introduction of bottom water into the gas part of the reservoir. The consequence of this is the presence of fluid in the production of wells, which is associated with pulling bottom water into the gas part of the reservoir and with the condensation of water vapor in the wellbore and the bottomhole formation zone. With increasing watering of the stock of producing wells, it becomes necessary to determine the amount of bottom and condensation water in the gas field.

In connection with the increase in water removal, the following problems arise:

- increased corrosion of the inner surface of pipelines and gas field equipment;

- increased load of liquid moisture at the input separators;

- water entering booster compressor stations and, as a result, salt deposition in the flow part of the superchargers.

The objective of the proposed solution is to determine the average specific and total amount of bottom and condensation water in the production of wells in the gas extraction zone.

The technical result is achieved by using the results of chemical analysis of water for total mineralization in the input separators to determine the proposed system of equations for the average specific and total amount of bottom and condensation water in the production of wells in the gas production selection zone.

The purpose of the invention is to improve the accuracy and efficiency of determining the water factor of the gas field.

This goal is achieved by the fact that in the proposed method for determining the water factor of a gas field, including collecting plantar and condensation water carried out from the well, separating it from the gas stream and mixing it in a separator, and determining the total mineralization of water, collecting the plantar and condensation water carried out from all wells gas production sampling zones, then samples of separated and mixed bottom and condensation water are taken and its chemical analysis is carried out for general mineralization, based on AANII which determine the material balance of mineralization by solving the equation:

,

,

where M1 is the mineralization of bottom water, g / m ³ , a constant indicator for the field;

X1 is the specific amount of plantar water, g / m ³ ;

M2 - mineralization of condensation water, g / m ³ ;

X2 - specific amount of condensation water, g / m ³ ;

M3 - mineralization of water after mixing in a separator, g / m ³ ;

then calculate the specific amount of bottom water in the gas field, taking M2 = 0, since condensation water in reservoir conditions is in the form of steam:

,

,

then determine the specific amount of condensation water in the gas field according to the formula:

X2 = (Wpl-Ws),

where Wpl - the equilibrium moisture content of the reservoir gas, g / m ³ ;

Wс - equilibrium moisture content of the gas in the separators, g / m ³ ;

the values of Wpl and Wc are calculated by the imperial formula used to determine the vapor content of moisture in natural gas depending on its pressure and temperature (Methodological guidelines for technological calculations of absorption gas drying systems. - Tyumen: NPO Tyumengaztekhnologiya, 1988, p. 17, f. 2.4).

W _pl = (0.457 / P _pl ) * exp (0.0735 * t _pl -0.00027t $\genfrac{}{}{0ex}{}{\text{2}}{\text{pl}}$ ) + 0,041 * exp (0,054 * t _pl -0,002 * t $\genfrac{}{}{0ex}{}{\text{2}}{\text{pl}}$ ),

where P _PL - reservoir gas pressure, kg / cm ² ;

T _PL - reservoir gas temperature, ° C;

W _s = (0.457 / P _s ) * exp (0.0735 * t _s -0.00027 * t $\genfrac{}{}{0ex}{}{\text{2}}{\text{from}}$ ) + 0.0418 * exp (0.054 * t _with -0.002 * t $\genfrac{}{}{0ex}{}{\text{2}}{\text{from}}$ ),

where P _{with the} gas pressure in the separator, kg / cm ² ;

T _with - gas temperature in the separator, ° C;

then determine the total amount of plantar and the total amount of condensation water per day:

Qп = Qг * X1 / ρп,

qк = Qг * X2 / ρк,

where: Qп - total amount of plantar water, m ³ / day;

Qg — gas flow rate through inlet separators, m ³ / day;

X1 is the specific amount of plantar water, g / m ³ ;

ρп - the density of bottom water, g / m ³ , a constant indicator for the field;

qк - total amount of condensation water, m ³ / day;

X2 - specific amount of condensation water, g / m ³ ;

ρк is the density of condensation water, g / m ³ , a constant indicator for the field;

and on the basis of the data obtained, the total amount of water in the gas field per day is calculated:

Q = Qп + qк,

where Q is the total amount of water in the gas field per day, m ³ / day.

The invention is illustrated by a schematic diagram of the gas collection in the gas field (drawing), where 1, 2, 3, 4, 5, 6 - wells of the gas field, 7, 8, 9, 10, 11, 12 - supply loops, 13 - input node , 14 - inlet separator, 15 - collection.

The method is implemented in the following way.

Gas from wells 1, 2, 3, 4, 5, 6 through the supply lines 7, 8, 9, 10, 11, 12 enters the inlet node 13, and then into the inlet separator 14, in which the formation gas is separated from the droplet liquid and mechanical impurities that accumulate in the collector 15. Mechanical impurities accumulate at the very bottom of the collector 15, and plantar and condensation water mixes. Then samples of this mixture of plantar and condensation water are taken and its analysis for general mineralization is carried out. Based on the data of chemical analysis, the material balance is determined by mineralization according to the formula:

(1),

(1),

where M1 is the mineralization of bottom water, g / m ³ , a constant indicator for the field,

M2 - mineralization of condensation water, g / m ³ ,

M3 - mineralization of water after mixing in a separator, g / m ^3,

X1 - the specific amount of plantar water, g / m ³ ,

X2 - specific amount of condensation water, g / m ³ ,

then calculate the specific amount of bottom water in the gas field, taking M2 = 0, since condensation water in reservoir conditions is in the form of steam:

(2),

(2)

where M1 is the mineralization of bottom water, g / m ³ , a constant indicator for the field,

M3 - mineralization of water after mixing in a separator, g / m ³ ,

X2 - specific amount of condensation water, g / m ³ ,

then determine the specific amount of condensation water in the gas field according to the formula:

X2 = (Wpl-Ws) (3)

where Wpl - the equilibrium moisture content of the reservoir gas, g / m ³

Wс - equilibrium moisture content of the gas in the separators, g / m ³ ,

the values of Wpl and Wc are calculated by a known method [3], after which the total amount of plantar and the total amount of condensation water per day are determined:

Qп = Qг * X1 / ρп (4),

qк = Qг * X2 / ρк (5),

where Qп - the total amount of plantar water, m ³ / day,

qк - total amount of condensation water, m ³ / day,

Qg - gas flow through inlet separators, m ³ / day,

X1 - the specific amount of plantar water, g / m ³ ,

X2 - specific amount of condensation water, g / m ³ ,

ρп - the density of bottom water, g / m ³ , a constant indicator for the field,

ρк is the density of condensation water, g / m ³ , a constant indicator for the field,

and on the basis of the data obtained, the total amount of water in the gas field per day is calculated:

Q = Qп + qк (6),

where Q is the total amount of gas in the gas field per day, m ³ / day.,

qк - total amount of condensation water, m ³ / day,

Qg - gas flow through inlet separators, m ³ / day.

Thus, using the system of equations 1 - 6, the average specific amount of plantar and condensation water in the gas field and the total amount of water per day in the gas field can be quickly determined from the chemical analysis for the total mineralization of water samples taken from inlet separators.

An example of a specific implementation of the method.

The Medvezhye gas field is operated by 305 producing wells and 9 integrated gas treatment facilities (GPP). At UKPG-8, field studies were conducted to determine the total amount of water that was discharged at the inlet separators per day by recording the amount of liquid discharged from the reservoirs. In addition, the amount of plantar, condensation water and their amount according to the proposed calculation were determined. During the calculations, the density of bottom and condensation water was taken: ρп = 1050 and ρк = 1000 kg / m ^3, respectively, mineralization of bottom water M1 = 19300 g / m ³ , mineralization of condensation water M2 = 0. Results of field studies, initial data and calculations are given in the table.

, то есть Х1 = 1315*0,653 / (19300-1315) = 0,048. Суммарное количество подошвенной воды определяется по формуле Qп = Qг*X1/ρп, то есть Qп = 14640000*0,048/1050000 = 0,7. Суммарное количество конденсационной воды определяется по формуле qк = Qг*X2/ρк, то есть Qк = 14640000*0,653/1000000 = 9,6. Суммарное количество подошвенной и количество конденсационной воды определяется по формуле Q = Qп + Qк, то есть Q = 0,7 + 9,6 = 10,3.For example, field studies from 13.10.00 determined the total amount of water that was discharged at inlet separators Q = 12.0 m ³ / day. According to the results of chemical analyzes, it was determined that the mineralization of water after mixing in a separator M3 = 1315 g / m ³ . The specific amount of condensation water in the gas field is determined according to the well-known method [3] according to the formula X2 = (Wpl-Wc), that is, X2 ₂ = 0.653 g / m ³ , under conditions: the equilibrium moisture content of the reservoir gas Wpl = 1.197 g / m ³ , at formation pressure values of 4.4 MPa and a temperature of 35.2 ° C, the equilibrium moisture content of gas in the separators is Wc = 0.544 g / m ³ , at separation values of 2.0 MPa and a temperature of 12.4 ° C. The gas flow through the inlet separators at the date of the study was Q _g = 14640 thousand m ³ / day. The specific amount of bottom water in a gas field is determined by the formula

, that is, X1 = 1315 * 0.653 / (19300-1315) = 0.048. The total amount of bottom water is determined by the formula Qп = Qг * X1 / ρп, that is, Qп = 14640000 * 0.048 / 1050000 = 0.7. The total amount of condensation water is determined by the formula qк = Qг * X2 / ρк, that is, Qк = 14640000 * 0.653 / 1000000 = 9.6. The total amount of plantar and the amount of condensation water is determined by the formula Q = Qп + Qк, that is, Q = 0.7 + 9.6 = 10.3.

The difference between the total amount of water discharged at the inlet separators per day (column 2) and the total amount of water determined by the proposed calculation (column 10) can be explained by the fact that, during field studies, the volume of carbonated liquid and mechanical impurities was recorded at pressure separation.

Thus, the data obtained will allow us to quickly monitor the change in the water factor. The application of the proposed method also allows to increase the accuracy of determining the water factor of the gas field, which will ensure the speed of regulation of the levels of gas withdrawal from production wells. This will prevent mineralized water from entering booster compressor stations and, as a result, salt deposits in the flow part of the superchargers, and take timely measures to:

- reduction of plantar water;

- reduce corrosion of the inner surface of pipelines and gas field equipment;

- reduce the load of liquid moisture inlet separators.

Sources of information

1. RF patent No. 2128280, IPC ⁶ E 21 V 43/00, publ. 03/27/99 Bull. Number 9.

2. Gvozdev B.P., Gritsenko A.I., Kornilov A.E. Exploitation of gas and gas condensate fields. - M .: Nedra, 1988, p. 282 (prototype).

3. Methodological guidelines for technological calculations of gas absorption drying systems. - Tyumen: NPO Tyumengaztekhnologiya, 1988, p. 17, f. 2.4.

Claims (1)

A method for determining the water factor of a gas field, including collecting plantar and condensation water carried out from the well, separating it from the gas stream, mixing it in a separator, and determining the total salinity of the water, characterized in that the outgoing plantar and condensation water is collected from all wells in the gas sampling zone field, then samples of the separated and mixed plantar and condensation water are taken and its chemical analysis is carried out for general mineralization, on the basis of which the material is determined athletic balance mineralization by solving the equation

where M1 is the mineralization of bottom water, g / m ³ ; constant indicator for the field; X1 is the specific amount of plantar water, g / m ³ ; M2 - mineralization of condensation water, g / m ³ ; X2 - specific amount of condensation water, g / m ³ ; M3 - mineralization of water after mixing in a separator, g / m ³ , then calculate the specific amount of bottom water in the gas field, taking M2 = 0, since condensation water in reservoir conditions is in the form of steam

then determine the specific amount of condensation water in the gas field according to the formula X2 = (Wpl-Wc), where Wpl is the moisture content of the reservoir gas in the form of water vapor, g / m ³ ; Wс - moisture content of gas in the separators in the form of water vapor, g / m ³ , then determine the total amount of plantar and the total amount of condensation water per day Qп = Qг · X1 / ρп qк = Qг · X2 / ρк, where Qп - total amount of plantar water, m ³ / day; Qg — gas flow rate through inlet separators, m ³ / day; X1 is the specific amount of plantar water, g / m ³ ; ρп - the density of bottom water, g / m ³ , a constant indicator for the field; qк - total amount of condensation water, m ³ / day; X2 - specific amount of condensation water, g / m ³ ; ρк is the density of condensation water, g / m ³ , a constant indicator for the field, and based on the data obtained, the total amount of water from the gas field per day is calculated Q = Qп + qк, where Q is the total amount of water in the gas field per day, m ³ / day.

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