RU2497574C2 - Method of load distribution between gas production complex gas drier shop process lines - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of natural gas, in particular, to gas drying with application of ACS PE to complex gas processing of gas condensate deposits in Far North. Gas flow rate ACS PE means are controlled in every i_th process line of said complex and compared with maximum permissible magnitudes and to automatically maintain said flow rate to conform with relationship

Hydraulic resistance of absorbers of every gas processing line is estimated. Only inspected absorbers with completely recovered serviceability are operated at maximum efficiency. Absorbers operated for a long time run in partial load mode. For this ACS PE defines the correction for absorber output ΔQ_i with allowance for parameters the measurement of which is impossible or unreasonable. Said correction is used to set and to maintain the output of every i_th absorber at the level calculated by the formula Q _{result. i}=Q_i-ΔQ_i, where Q_i is the design magnitude of required efficiency of i_th process line. Note here that ACS PE follows the conditions consisting in that total output of gas production complex

equals the magnitude set of central dispatcher service for gas production complex.

EFFECT: efficient gas drying at minimum power and material input, decreased number of personnel.

2 cl, 3 dwg

Description

The invention relates to the field of natural gas production and, in particular, to the conduct of the gas drying process using automated process control systems (ACS) of integrated gas treatment plants (UKPG) of gas condensate fields of the Far North (gas production complexes).

(см. Тараненко Б.Ф., Герман В.Т. Автоматическое управление газопромысловыми объектами. М., «Недра», 1976, 213 с.).A known method of conducting a gas drying process, including controlling by means of an automated process control system the gas flow rate for each i-th technological string of the gas production complex, its comparison with the maximum permissible values and automatic maintenance of the gas flow rate subject to the conditions

(see Taranenko B.F., German V.T. Automatic control of gas production facilities. M., "Nedra", 1976, 213 pp.).

A significant drawback of this method is that it does not take into account all disturbing factors and excludes a full adjustment of the technological process flowing in the gas preparation process line (TLPG). Correction is carried out only for those parameters whose values are measured by means of industrial control systems. In practice, there are a number of parameters (the amount of produced formation and methanol water in the absorber, the amount of mechanical impurities that enter the absorber with gas, the number of ingredients in the reagent for gas dehydration, etc.), which can significantly affect the hydraulic resistance of TLHG and ultimately on the progress of the process. Fundamentally, their values are either impossible or impractical to measure by means of automated process control systems because of the high cost of measuring equipment.

(см. Исакович Р.Я., Логинов В.И., Попадько В.Е. Автоматизация производственных процессов нефтяной и газовой промышленности. Учебник для вузов. М., Недра, 1983, 424 с.).A known method of controlling the process of gas dehydration, including control by means of automatic process control systems of gas flow for each i-th technological string of the gas production complex, its comparison with the maximum permissible values and automatic maintenance of gas flow in compliance with the conditions

(see Isakovich R.Ya., Loginov V.I., Popadko V.E. Automation of production processes in the oil and gas industry. Textbook for high schools. M., Nedra, 1983, 424 pp.).

, но без учета тех параметров, значения которых нельзя определить средствами АСУ ТП из-за отсутствия средств измерения либо из-за высокой стоимости этих измерений.A significant drawback of this method is that it does not take into account all disturbing factors and excludes a full adjustment of the process flow that takes place in the process line of gas preparation. Correction is carried out only for those parameters whose values are measured by means of industrial control systems. This method allows you to control the process of drying gas in automatic mode within the specified value

, but without taking into account those parameters whose values cannot be determined by means of industrial control systems due to the lack of measuring instruments or because of the high cost of these measurements.

, (см. патент РФ №2 344 339 «Способ управления технологическими процессами газового промысла»).The closest in technical essence to the claimed invention is a method of controlling the gas drying process, including controlling by means of an automated process control system of gas flow for each i-th technological string of the gas production complex, its comparison with the maximum permissible values and automatic maintenance of the flow subject to the conditions

, (see RF patent No. 2 344 339 "Method for the control of technological processes in the gas field").

, но без учета тех параметров, значения которых нельзя определить средствами АСУ ТП из-за отсутствия средств измерения либо из-за высокой стоимости этих измерений.A significant drawback of this method is that it does not take into account all disturbing factors and excludes a full adjustment of the process flow that takes place in the gas preparation process line. Correction is carried out only for those parameters whose values are measured by means of industrial control systems. This method allows you to control the process of drying gas in automatic mode within the specified value

, but without taking into account those parameters whose values cannot be determined by means of industrial control systems due to the lack of measuring instruments or because of the high cost of these measurements.

The aim of the present invention is to control the process of drying gas in an automatic mode within specified limits, taking into account all the disturbing factors affecting the process.

The technical result achieved by the implementation of the present invention is to provide a given degree of gas dehydration with minimal energy and material costs and compliance with all restrictions on the process parameters.

была равна заданной центральной диспетчерской службой для газодобывающего комплекса.This goal is achieved due to the fact that during the operation of the gas production complex, the hydraulic resistance of the absorber of each gas processing line is evaluated, and those absorbers that have just been inspected and restored to their full capacity are operated at maximum capacity. Those absorbers that have been in operation for quite a long time are operated in a gentle manner. For this, the automatic process control system determines the value of the correction for the performance of each absorber ΔQ _i taking into account parameters that are impossible and / or inexpedient to measure, and uses this correction to set and maintain the performance of the i-th absorber at the level calculated by the formula Q _{results. i} = Q _i -ΔQ _i , where Q _{i is the} estimated value of the required productivity of the i-th technological thread. At the same time, the automatic process control system monitors the fulfillment of the condition so that the total productivity of the gas production complex

was equal to the specified central dispatch service for the gas production complex.

The value of the correction for the productivity of each absorber ΔQ _i is determined taking into account the condition of the equipment, the quality of the gas coming from the wells, parameters that are impossible and / or inexpedient to measure, and formalized knowledge of professional experts in the form of fuzzy logic logic-linguistic models. The correction ΔQ _i is determined by the ACS TP subsystem, which has an appropriate knowledge base and implements a complex fuzzy logic algorithm.

The inventive method is implemented as follows. Those absorbers that have just undergone an audit, and their full functionality has been restored, are operated in maximum performance mode. Absorbers that have been in operation for quite a long time (continuously operated for more than six months) are operated in a gentle manner.

The condition of the absorbers, the amount of produced formation and methanol water, the amount of mechanical impurity that enters the absorber with gas, the number of ingredients in the composition of the reagent for drying, etc., which strongly affect the hydraulic resistance of the absorbers, are not measured in real time by automated process control systems . This is due to the fact that they cannot be quantified due to the lack of appropriate technical means of measurement or the economic inappropriateness of their use. Therefore, to determine the operating mode of the absorbers, regularly, in accordance with the technological regulations of the gas production complex, maintenance personnel and specialists of the relevant services (technologists, geologists, chemists, etc.) analyze the status of each absorber.

For this purpose, the amount of produced formation and methanol water, the amount of mechanical impurities entering the absorber with gas, the amount of ingredients in the reagent for drying, etc., are specified using various methods of physicochemical laboratory analysis. The indicated parameters relate to parameters slowly varying in time, and for some time (a given time interval between the analyzes), they can be considered quasistationary.

The state of the i-th absorber is descriptive and largely subjective. Based on the experience of operating the field and quantitatively controlled parameters by means of automated process control systems and the results of standard periodic laboratory tests, the operator (expert) describes the state of each adsorber, registering it in the relevant journals. The described condition of the equipment of each absorber expert evaluates conditionally quantitatively. For this purpose, for example, the interval [0,1] is divided into ten parts with a step of 0.1 (a conditional scale of 10 steps to assess the level of the described parameter: from a low level to an average level, and then to a high level).

Accounting in ACS TP parameters that are not amenable to quantitative assessment is possible using a block that implements a complex algorithm of fuzzy logic with an appropriate knowledge base. A complex algorithm of fuzzy logic is used to calculate the load distribution between the TLG, which allows us to implement the inventive method and realize the goals. The principle of operation of industrial control systems with the indicated unit and knowledge base (KB) is described below.

The input variables of the block that implements the complex fuzzy logic algorithm are: X1 _i - equipment status (CO); X2 _i is the quality of the incoming gas (CNG) for drying. For simplicity of exposition of the principle of operation of the algorithm under the parameter X2 _{i, we} combine several parameters that are not directly measurable by automated process control systems, but are periodically monitored by laboratory methods. These include, in particular: the amount of incoming formation and methanol water; amount of mechanical impurities entering the absorber with gas; the amount of ingredients in the composition of the reagent for drying, etc.

The output of the block that implements the complex fuzzy logic algorithm is an expert correction to the performance of the ith absorber ΔQ _i . After determining the correction ΔQ _{i, the} resulting productivity of the technological process control line is determined by the ratio:

Q _{rez. i} = Q _i -ΔQ _i

where Q _i is the calculated value of the required productivity of the i-th technological thread.

Such a sequence of solving the problem requires the creation of a knowledge base of professional experts (operators) to determine the expert amendment ΔQ _i . The use of knowledge of professional experts (operators) in the system is based on logical-linguistic models in the form of fuzzy logic products. This is due to the fact that it is an expert, based on his highly professional experience and intuition, acquired over several years of painstaking work, that can correctly assess the influence of the characteristics X1 _i , X2 _i on the performance of TLGs, which cannot be described in the framework of clear mathematical models.

The fuzzy logic algorithm works as follows (see Fig. 1): from the KB of the system, the values of X1 _i , X2 _i are fed to the input of the fuzzification unit (BF). The scale, which includes information about these parameters, is conditionally divided into ten parts in the interval [0,1].

The BF transforms clear signals into fuzzy sets. For this, the fuzzification operator is used (see R.A. Aliev, P.P. Aliev. SOFT COMPUTING. In 3 hours, Part 1: Fuzzy sets and systems. - Baku: AGNA, 1998. - 181 pp.):

F = fuzzifier (x ₀ ),

where x ₀ is a clear signal input to the fuzzification unit;

F is a fuzzy set;

fuzzifier - fuzzification operator.

The input signal x _{0 is} converted into a fuzzy set with membership function µ (x), moreover, the distribution form of the values of each fuzzy variable is accepted in a triangular form, i.e. membership function is determined by the expression:

- среднее значение сигнала;Where

- the average value of the signal;

α and β the left and right deviations from the center, in which the value of the function µ (x) = 1;

x is the current signal value.

The value of each variable in the KB is represented by three fuzzy linguistic terms (“low” - H, “medium” - C, “high” - B). As a result, the total number of production rules is 9.

Below is the content of the knowledge base of the control system that implements the fuzzy logic algorithm for parameters X1 _i and X _2i .

P1. IF: X1 _i = “H” and X2 _i and “H”, THEN “H”

P2. IF: X1 _i = “H” and X2 _i and “C”, THEN “H”

P3. IF: X1 _i = “H” and X2 _i and “B”, THEN “H”

P4. IF: X1 _i = “C” and X2 _i and “H”, THEN “H”

A5. IF: X1 _i = “C” and X2 _i and “C”, THEN “H”

P6. IF: X1 _i = "C" and X2 _i and "B", THEN "C"

P7. IF: X1 _i = “B” and X2 _i and “H”, THEN “C”

P8. IF: X1 _i = "B" and X2 _i and "C", THEN "B"

P9. IF: X1 _i = "B" and X2 _i and "B", THEN "B"

The operator (expert) should have the opportunity to interactively edit the contents of the knowledge base taking into account the experience of automated process control systems.

Figure 2 shows the forms of linguistic terms X1 _i , X2 _i and ΔQ _i .

Upon receipt of the input signals to the input of the BF determines their belonging to a particular term. The logical output unit (BLV) activates the corresponding rules in which the membership function for all input signals is greater than zero. After the rules are triggered, a logical conclusion is made on the basis of the max-min Zade rule (see R.A. Aliev, PP Aliev. SOFT COMPUTING. In 3 hours, Part 1: Fuzzy sets and systems. - Baku: AGNA, 1998. - 181 c.): It for the given process has the following form:

µ (y) = max min {µ (x) ₁ , µ (x) ₂ , ..., µ (x) _n }

where n is the number of input parameters of the fuzzy system (for this case, n = 2)

Moreover, for each activated rule, the value of the minimum function of membership of the input signals is found. The calculated value of the membership function determines the area of the output fuzzy signal. Further, at the outputs of the activated rules, all received output fuzzy signals are summed. After summing in the block of defuzzification (BDF), the process of reverse transformation of the fuzzy signal into a clear signal is carried out. The Center of Gravity method is used (see R.A. Aliev, PP Aliev. SOFT COMPUTING. In 3 hours, Part 1: Fuzzy sets and systems. - Baku: AGNA, 1998. - 181 pp.), Whereby

where y _k , µ (y _k ) is the minimum value and membership function of the input variables x ₁ , ... x _n .

Figure 3 shows a geometric representation of the mechanism for obtaining fuzzy inference.

After defuzzification, the signal enters the automatic process control system of the gas production complex, which gives the correction value ΔQ _i for the i-th adsorber, after which the resulting productivity is determined from formula (1) - Q _result i of the i-th technological thread.

The proposed method of load distribution between the TLPG using the integrated fuzzy logic algorithm allows you to: fully take into account the influence of all factors (even not directly quantifiable) on the productivity of each gas preparation line in the gas treatment plant, which significantly improves the quality of the gas being prepared and allows more efficient use of the technological equipment.

The claimed invention is worked out and implemented at the automated process control system of the gas treatment plant at the Yamburgskoye oil and gas condensate field. The results of operation have shown its high efficiency. The claimed invention can be widely used in other existing and newly developed gas condensate fields of the Nadym-Purtazov gas province, the Yamal and Gydansky peninsulas.

Claims (2)

1. The method of load distribution between the production lines of the gas dehydration plant of the gas production complex, including control by means of automated process control systems of gas consumption for each i-th technological string of the gas production complex, its comparison with the maximum permissible values and automatic maintenance of the flow subject to the conditions

, characterized in that the hydraulic resistance of the absorbers of each gas preparation line is evaluated, and those absorbers that have just been inspected, and their functionality has been fully restored, are operated at maximum capacity, and those absorbers that have been in operation for quite some time - operate in the power saving mode, for which the ACS determines the correction value on the performance of each absorber ΔQ _i with the parameters, which is impossible and / or netselesoobra but measured, and uses this correction to set and maintain the performance of i-th absorber at a level computed by the formula Q _{the results. i} = Q _i -ΔQ _i , where Q _i is the calculated value of the required productivity of the i-th technological string, while the automatic process control system monitors the fulfillment of the condition that the total productivity of the gas production complex

was equal to the specified central dispatch service for the gas production complex. 2. The method according to claim 1, characterized in that the value of the correction for the performance of each absorber ΔQ _i taking into account the condition of the equipment, the quality of the incoming gas, parameters that are impossible and / or impractical to measure, and formalized knowledge of professional experts in the form of fuzzy logic products logical-linguistic models, determines the subsystem of industrial control system, which has an appropriate knowledge base and implements a complex algorithm of fuzzy logic.

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