RU1794179C - Method for determination of working conditions of a gas-lift wells system - Google Patents

Description

(5,) 2

CoI 1

Ј 1 / Ai

I 1

(6)

+ 2 s,

i 1

When implementing the method, operations are carried out in four stages.

At the first stage, the operating mode of the well-formation system is affected by changing: the volume of fluid supplied to the formation through injection wells; compressed gas flow rate; modes (stop or start) of a group of wells; operating modes of the oil and gas gathering system. Thereby, the technological parameters of the gas-lift wells reacting to this disturbance are changed (for example, flow rate, gas operating pressure, wellhead pressure or temperature, dynamic level, pressure in the gas-lift or in the bottom of the well) and the dynamics of these parameters in time is obtained for each gas lift complex wells. In a second step, the interacting wells of the gas lift complex are determined.

A study of the interaction between gas lift wells is carried out by static methods based on an analysis of time series of observations of the dynamics of changes in technological parameters for wells that respond to perturbations of the well system + formation (these parameters may be different depending on the nature and operating conditions).

The degree of interaction is determined by the nature of the inter-correlation functions:

Rxy (t)

1

T V Dx Dy x Y (t - g) - (5)

where X (t), Y (t) is the dynamics of the change of technological parameters on an arbitrarily selected pair of wells;

X, Y, and Dx, Dy, respectively, the mothers and the variance of the processes;

T is the period of observation of the dynamics of changes in the technological parameters;

g - the delay of the response to the disturbance.

The expectation and variance are determined from the following formulas:

1

- p -.,., - 7 In a discrete form and after centering the processes, formula (5) is written in the following form: - 1 n-k

RxyCk)

(n-k) -VDx -Dy i,

I X, - X x Y (l - k) - k Orn

(8)

where m is the maximum delay adopted in the calculations.

The identification of interacting wells from a common system is carried out in the following sequence:

determining a change in the correlation between the process parameters from the influence of a delay in the response of the mode under disturbance;

using change correlation

For each pair of wells, the maximum value RXy (k) is determined, which, depending on the objective operating conditions, may correspond to different delays;

the found maximum Rxy values for the studied wells are reduced to an information matrix in the form:

(N, 1N)

flRi, 2max

Ji R2, imax 1

II i |

j | RN, imaXRN, 2maX

RI.N

;

R2, Nmax i

1

(9)

using the information matrix (9), interacting wells from the entire system are revealed for which Rxy (k) Rmin.

In the third stage, interacting gas lift wells are examined in several steady-state modes by

changes in gas flow rate. In this case, for each mode, the flow rate and gas flow rate are measured, after which for the 1st well the coefficients AI, Bi, Q are determined for the dependence of flow rate on gas flow (for example, by the least squares method). For gas-lift wells, the dependence of flow rate on gas flow can be represented as:

71794179 8

Qi Ar Vi2 + BI-Vi + Ci It is assumed that for all wells, AI C is for Vi 0; The Bi 0 (10) systems are known for the Q f (V) curves in the form At the fourth stage, the optimo-mathematical dependence (10) is carried out. At the same time, the work of interacting gas-lift-flow rate and flow rate of the 1st well of the defined wells is at the same time. Moreover, as criterion 5 by the formula: optimality take: maximization

oil production with limited resource Vi (Ej-Bi) / 2Ai; I 1, n (14) gas; minimization of total gas consumption with limited production; minimization of Qi Ci + (Ej - BI) / 4Ai (15) specific gas consumption. 10

For all cases, the solution is fulfilled. In this case, the total gas flow rate and, if the bit efficiency indicator is equal, will be as follows: the gas use, i.e. differentials

oil flow rates for gas consumption for all, l, .... L,. wells. Then for the considered criteria 15 (tj // Ai - bj criteria, the following equality holds:

i (hell): I 1

Qomax (Vo) if Ej EoЈ Q, (Ej) - Ј Ej2 / 4Ai -. B | 2 / 4A | +

01) 20

1 11 1

n

Qo (V0) Qomax (Vo) if Ej Eoi 1

| Vom1n (Qo), if Ej EoIf the efficiency of utilization is equal,,. I, „., No gas A7151 of all wells is obtained: 2. Vi (Ej) r | (12) b

LVo (Qo) Vomln (Qo) if Ej EoJ Vi (Eo) - Eo J1 / 2A | -. Bi / 2AI (18)

Lvo (Qo) Vomln (Qo) if Ej Eo

1 11 1 1 1 i Romln if Е Ео Ro (Јjjp

thirteen). Qi (Eo) Eo2. 1 / 4Ar Bi2 / 4A, +

thirteen). Qi (Eo) Eo2. 1 / 4Ar Bi2 / 4A, +

LRo Rom1n. if Ej i-1

v, 5 Ci (19) where Vo 2, Vi (Ej) is the total gas consumption i 1

35 From solution (16) and (18) or (17) and (19) dl for wells, m / day; conditions:

Qo Y Qi (Ei) is the total production rate of the squad. d. n

) Qi (Eo) for

Zh.t / day; 40 -1 1 1

Ej (dQi / dVi) j is the efficiency indicator Vi (Eo) of gas utilization for the 1st well i 1 in the Jth mode, t / m3;

Eo d (Y Q0 / d (2 Vi) - exponent 45 2 Vi (E); v Vi (Eo) npn) Qi (Ej)

gas utilization efficiency according to the QQ (EO) system

me interacting gas lift squa-i 1

Zh.t / m3; (20)

zi are: 0 2 / Vi / 2, Qi is the total gas flow

n

TW / A7

1 (21)

per production unit, m3 / t. EJ / AI

To assert condition (11). (12) and (13) .ZJ

it is enough to prove that the total flow rate of 55 V i / d

(or gas flow rate) for various effects, -

gas utilization in wells. Obviously, the inequality always fulfills less (or more) than with their for the working area of the Qi dependence

equality., that is, the following ranges:

I 1 / A,

 1

Ј Q, (Ej) - Ј Ej2 / 4Ai -.

01) 20

1 11 1

n

1 11 1 1 1

thirteen). Qi (Eo) Eo2. 1 / 4Ar Bi2 / 4A, +

 i-1

TW / A7

1 (21)

then the inequality holds I 1 / A,

 1

About Ej (dQi / dVi) j (AQi / AVi) 0 Ai - 0.5d2Qi / d Vi2 0.5 (A / x (AQi / AVi) J 1

1 1 AVflxj

(22)

Condition (21) and (22) confirm the optimality for the criteria under consideration when the gas utilization efficiency in all wells is equal.

Formulas (1), (2) and (3) describing the technological modes of well operation are obtained from solving a system of equations consisting of dependences (10) for optimality conditions (11). (12) and (13). For example, when formula (1) is obtained, Eo is determined from equation (18) and put into equation (14), and when formula (2) is determined, Eo is found from equation (19) and also put into equation (14).

To determine the formula (3) first

a curve is established (2 QI x K 2 Vi). For this, Eo is found from equality (18) and put into equation (19), as a result,

| Qi-Ao (J Vtf + Bo | Vi + Co, (23)

where AO, Bo, Co are the coefficients for the dependence 2Qi f (2 Vi)

To differentiate dependence (23), learn:

d (S Vi / J Qi)

 eleven

Vi + Vo + Co / Ј Vi

1

Ao - Co / I v) 2 - O

(26)

i 1

5 i vco Ј I / A, -f27)

1-11 1 where 2) Vi is the total gas flow through wells 10. corresponding to the minimum gas consumption per unit of production, m / day.

Solving equations (27), (18) and (14), formula (3) is defined.

15 The optimization process is carried out as follows.

Technological modes of Vi are found and established at the wells, their actual flow rates are measured (after the expiration of the delay time of the response to the system disturbance) and compared with the calculated ones:

if the calculated and actual flow rates coincide (within the measurement error), the operating mode for the interacting gas-lift wells is considered optimal;

if the calculated and actual flow rates for any wells do not match, then the coefficients AI, Bi, and O for these wells

30 wells, on the other hand, are corrected according to newly obtained production rates by static methods (for example, least squares), and then their values are put into formulas (1), (2) or (3) and, accordingly, new ones are determined

35 values of technological modes, and this process is repeated until equality is reached between the calculated and the actual. flow rate.

Examples of calculation results for revealing interacting wells are given in Table. 1 and 2 and are graphically illustrated in the drawing. In the table. Table 1 shows the values of measurements of technological parameters for calculation, in table. 2 shown

45 results of the identification of interacting wells by the maximum values of correlation communication.

The drawing shows the nature of the change in the technological parameter over time, as well as the dependence of the correlation coefficient on the delay of the response to disturbance. The correlation between wells No. 1 and No. b is relatively high in step k, i.e. their degree

55 interactions after 90 minutes is 0.72, while at 15 minutes delay this value is 0.3.

An example of the results of optimizing the operation of interacting wells is given in jaQn. 3.4 and 5. In table 3, the initial data for the calculation are given. In the table. Figure 4 shows the results of optimization according to formula 1 (maximization of oil production with a limited gas resource of 100 thousand m3 / day) or according to the formula

Claims (4)

1. A method for determining the operating mode of a system of gas lift wells, including measuring the technological parameters of the wells and determining the correlation between them, finding the interacting wells, determining for them the curves of the flow rate versus the gas flow rate and the process conditions, restoring the values of the latter at the wells, measuring their flow rates and comparing them with the calculated ones, and repeating the operation of determining the technological regimes until the optimum operation of the interacting wells is achieved, and in order to increase the efficiency of the method by increasing the accuracy of choosing the optimal operating modes for gas lift wells, they preliminarily disturb the operation of the well-reservoir system and measure the technological parameters in the wells that respond to this disturbance and determine the dynamics of their change over time for each well, there is a change in the correlation between technological parameters from the time the reaction response is delayed when they are disturbed and interacting wells are extracted from the maximum values Then, after determining the coefficients of the dependence of the flow rate on the gas flow rate, the technological modes are found, and after setting their values, the well production rate is measured from the moment the response time of the response to the disturbance expires, and when the flow rates are mismatched with the calculated flow rates, the flow rate dependence coefficients are adjusted and accordingly, new values of the process conditions are determined. 2. The method according to p. 1, characterized in that with a limited compressed gas resource, the technological conditions are determined from the following ratio: 2 (minimization of the total gas consumption while restricting oil production to 488.3 tons / day), and in table. 5 - optimization results according to formula 3 (minimizing gas consumption per unit of oil production). Vn + 2 Bi / 2Ai VI - Vo + ----- Bi / 2Ai AI Ј 1 / Ai where Vi is the technological gas flow rate for the 1st well, m3 / day; VQ - limited compressed gas resource for interacting gas-lift wells, m3 / day ;, AiBiCi - coefficients approximating the dependence of flow rate on gas flow for the i-th well of the second degree polynomial (Qi AiVi2 + В iVi + Ci), Qi - flow rate of the 1st well t / day. 3. The method according to p. 1, characterized in that with limited production, technological modes are determined from the following ratio: Vi - 1 VQ0 + 2 V7 / 4A, -2C, Ai Si 2Ai I I / A. where Qo - limited (predetermined) production by interacting gas lift wells, t / day; 4. The way to pop. 1, characterized in that while minimizing the specific volume of compressed gas per unit of production, the technological conditions are determined from the following ratio: 45 Vi Co + 2 I / + 2 V / 2 A, Ai 2 1 / Ar fifty B, 2Ai Co (2A.1B | 2 / 4D | +1 I I / At Ci. 55. Note. The correlation bond Rxy (k) is high - more than 0.5 between a pair of wells - No. 2 and No. 4, No. 5 and No. 2. No. 3 and No. 6, and the first group of interacting wells consists of numbers 2,4 and 5, and the second - from 3 and 6. Table3 Table 1 Table 2 Table 4 Table 5