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

343

2

al. (2019)). Minimizing the impact of oil spills on the environment depends on the promptness of work to localize the source of pollution and competent and timely measures to eliminate the accident consequences. In recent years, solving the problem of ensuring the industrial and environmental safety of pipeline transport has become especially important. The problem of detecting oil leaks, especially "small" ones, from main pipelines is one of the most acute and difficult problems of oil pipelines operation (Yavorskyi et al. (2017), Poberezhny et al. (2019)). Despite the fact that the search for effective and technological solutions is constantly being carried out, it is not yet necessary to talk about a final solution to this problem. There are many methods for detecting leaks, both calculated and technical, but most of them are technologically complex or expensive. Also, the detection of oil leaks from the cavity of the pipeline becomes more complicated when transient processes occur (starting, stopping pumping units, switching tanks, etc.) (Serediuk and Grygorskyi (2015, 2016)). 2. Material and methods One of the simplest and cheapest methods for determining oil leaks from a main oil pipeline is the method of hydraulic leak location. It is based on the analysis of the hydraulic characteristics of the pipeline section on two specially selected baseline segments located near oil pumping stations (OPS). The task is to indicate the location of the oil leak and estimate its intensity from the change in hydraulic slopes on these segments. This method makes it possible to localize oil leakage from the pipeline and calculate the amount of oil flowing out through a small hole in a stationary mode of the pipeline operation without stopping pumping. By the term "small hole" we mean a hole of such a small area in the pipeline that even with a complete stop of the oil pipeline, the liquid flowing out does not create any noticeable movement in the pipe and the oil in the pipe can be considered stationary (the classical hydrostatic formula is valid for the pressure distribution in the oil pipeline). To construct mathematical models that make it possible to obtain information about the volumetric flow rate q and the location of a small oil leak due to pipeline damage x , it is necessary to calculate the throughput of an oil pipeline in a stationary mode of operation without and taking into account oil leakage. The algorithm for determining the throughput of an oil pipeline consists of the following calculation blocks: 1) operating mode of the linear part (calculation of total pressure losses i tot P , i tot P  ) according to the formulas: - for hermetic linear sections of the oil pipeline (without oil leaks) 1, 02 ; i i tot h i i P i L g z  =   +    (1)

- for oil pipeline sections with low oil leakage

(

)

(2)

 

 



h 

L x 

1, 02 = 

,

P

i x i

g z  − +   

 + 

tot

h

і

i

і

i

i

i

i

where i h i , i h i  – hydraulic tilt in sections of the pipeline before and after oil leakage through a small hole in the pipeline; i L , i L  – the geometric length of the sealed section of the oil pipeline and the section on which a small hole was formed, m; і x – linear coordinate of the leakage section, counted from the beginning of the i-th stretch, where a through hole was formed in the pipeline, m;  – oil density when pumping, kg/m 3 ; g – acceleration of gravity, m/s 2 ; i z  ‒ difference of geodetic marks of the end and the beginning of the i-th section of the oil pipeline between two adjacent OPS, m; 2) operating mode of OPS (calculation of the pressure і ops P created by centrifugal pumps):

3 1 1 0 j k = = =   i n r i   

  

(3)

,

k

P

g =   

a Q 

ops

k

, i j

і

where , i j k a are coefficients of the mathematical model of the pressure characteristic of the j -th centrifugal pump installed on the i -th pump station (obtained by processing the passport characteristics of the pressure of each pump