PSI - Issue 36

S. Hryhorskyi et al. / Procedia Structural Integrity 36 (2022) 342–349 S. Hryhorskyi et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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For the analytical model (21) and the specified operating mode of the oil pipeline, the coefficients are 3 4.211 10 Q A − = −  , 1 9.105 10 Q B − =  . Similarly, the coefficients of the mathematical models (16) - (20) are obtained during depressurization of the second and third linear sections of the investigated oil pipeline. Table 3. The value of the coefficients of the mathematical models (16) - (19) for calculating the dynamics of pressure changes at the inlet and outlet of each OPS of the oil pipeline. Value i, j , i j out A , i j out B , i j inp A , i j inp B

j = 1 j = 2 j = 3 j = 1 j = 2 j = 3 j = 1 j = 2 j = 3

4. 469·10 -9 -7. 577·10 -7 -1. 408·10 -5 2. 587·10 -11 -1. 742·10 -9 -6. 448·10 -8 7. 370·10 -12 -4. 965·10 -10 -2. 081·10 -8

3. 836·10 -10 2. 326·10 -6 -5. 240·10 -4 1. 142·10 -10 -1. 712·10 -5 -3. 528·10 -4 2. 505·10 -10 -5. 335·10 -6 -1. 095·10 -4

‒ ‒ ‒

‒ ‒ ‒

i = 1

2. 794·10 -11 -1. 884·10 -9 -6. 754·10 -8 1. 152·10 -11 -7. 813·10 -10 -2. 692·10 -8

-2. 399·10 -11 -1. 813·10 -5 -3. 741·10 -4 -5. 135·10 -11 -7. 362·10 -6 -1. 522·10 -4

i = 2

i = 3

Table 4. The value of the coefficients of mathematical model (20) for calculating the maximum possible loss of oil from infiltration into the soil. , inf i j A j = 1 j = 2 j = 3 i = 1 4. 472·10 -8 -4. 234·10 -5 -2. 582·10 -3 i = 2 -3. 573·10 -6 3. 401·10 -3 1. 810·10 -1 i = 3 -2. 632·10 -5 2. 499·10 -2 1. 539·10 0

Based on the results of the performed calculations. a graphical dependence was built. reflecting the dynamics of changes in the throughput of the oil pipeline on the flow of oil through the hole and its location on the pipeline route (Fig. 2a). The results of calculations of the maximum oil losses due to infiltration into the soil during the time of oil leakage through the hole are shown in Fig. 2b. The calculations were performed for light loams ( 6 5 10 / f k м с − =  . 0,07 p m = ) and an almost horizontal soil surface. The actual throughput of the oil pipeline Q  linearly depends on the oil flow through the hole and increases with a decrease in the linear coordinate of the section where the through hole 0 q = was formed in the pipeline (Fig. 2a). As for the volumes of oil losses into the environment (Fig. 2b), the dependence is nonlinear on the volumetric leakage rate and the duration of infiltration.

a)

b)

Fig. 2. Dependence of the change in the throughput of the investigated oil pipeline on the volumetric flow rate of oil through the hole and its location (a); dependence of the change in the maximum possible oil losses from infiltration into the soil on the volumetric oil flow through the hole and the time before the start of emergency recovery work (b)