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Ramiz Ismayilov, Ragiya Asgerova
RISK REDUCTION IN WELL FLOW LINES BASED...
RT&A, Special Issue № 6 (81), Part-1,
_________Volume 19, December 2024
RISK REDUCTION IN WELL FLOW LINES BASED ON EARLY DIAGNOSIS OF COMPLICATIONS
Ramiz Ismayilov, Rugiya Asgerova
Azerbaijan State Oil and Industry University [email protected] [email protected]
Abstract
The reliability of the system for collecting products from oil, gas and gas condensate fields directly depends on the condition of the well flow lines. Many years of experience in the exploitation of offshore fields in the Azerbaijani sector of the Caspian Sea shows that various kinds of complications arise in the flow lines of wells associated with salt deposits, asphalt base, tarry oil and paraffin deposits, fluid accumulation, pressure pulsations, etc.
The listed complications lead to the formation of blockages in the flow lines, an increase in the mechanical load on the equipment and, ultimately, to a decrease in the productivity of lines and wells, up to the point of stopping their operation. Work to restore these lines takes quite a long time and requires significant costs.
Reducing technological risks in the operation of well flow lines is closely related to diagnosing their condition. But planned diagnostic work involving forces and equipment often in practice reveals complications at a late stage of their development and engineering decisions are made to shut down wells and restore lines.
In connection with the above, the issues of diagnosing complications at an early stage of their formation acquire current and practical importance. Timely cleaning of flow lines and regulation of operating conditions of production wells, such as the selection of an adequate wellhead pressure regime and other technological solutions, can prevent a negative scenario for the development of complications. In turn, for early diagnosis of complications it is necessary to find a diagnostic criterion. determining the beginning of their formation. Due to the fact that the main flow parameters at the metering nodes are continuously recorded in real time, it would be advisable to develop an appropriate diagnostic criterion based on the results of studying the dynamics of time series for the main indicators of flow lines.
For this purpose, in this work, flow lines of wells in the Bulla-Deniz field (Azerbaijan) were studied. The main indicators for the studied lines were length and diameter, pressure at the beginning and end of the line, gas factor and line productivity. Based on these indicators, data processing was carried out and corresponding statistical estimates were obtained.
The results of the analysis revealed a stable correlation between gas factor indicators and flow line performance. It was established that a sharp decrease in line productivity with an increase in the gas factor manifested itself in wells in which restoration work was carried out due to complications that arose. This makes it possible to use this behavior of the curves of the dependence of flow line productivity on the gas factor as a criterion for diagnosing complications at an early stage of their formation.
The results of this research can be recommended for use in the operation of a system for collecting and transporting oil and gas field products.
Keywords: flow lines, risk analysis, diagnosis of complications, gas factor, line productivity
I. Introduction
Well flow lines, as an element of the gas and oil collection network, are pipelines originating at the wellhead and ending at the entrance to group metering installations [1]. Many years of
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Ramiz Ismayilov, Ragiya Asgerova
RISK REDUCTION IN WELL FLOW LINES BASED...
RT&A, Special Issue № 6 (81), Part-1,
_________Volume 19, December 2024
operating experience show that various kinds of complications arise in flow lines, the elimination of which requires stopping the operation of wells and carrying out repair work, accompanied by significant downtime and, as a consequence, material and labor costs.
In work [2], using the example of Russian fields, it is shown that the accumulation of liquid, especially at the late stage of development, leads to a number of complications both in flow lines and in the operation of process equipment at the collection point. Among them, one can highlight an increase in hydraulic resistance, the observation of volley releases of liquid into separation units, pressure pulsations and the formation of hydrate plugs with a decrease in temperature in winter. The authors here also propose, in order to reduce the risk of liquid accumulation, optimal regulation of gas extraction modes, which, ultimately, should also significantly increase the operating efficiency of separation units.
The authors in another work [3] list asphalt base oil, tarry oil and paraffin deposits, the formation of emulsions, hydrates, and inorganic salts as the main factors leading to complications in field pipelines. The researchers in this work brought some clarity to the conditions and mechanism of formation of the above factors and listed existing methods for reducing the risk of their formation.
Technological risks associated with the formation of hydrate plugs and the loss of paraffin deposits in pipeline lines have been studied in detail in studies [4]. Here, the authors proposed a probabilistic model for assessing the above risks in pipelines transporting oil and gas, tested it on real field data and showed fairly good performance.
In offshore oil and gas production, flow lines are connected to a subsea pipeline that transports well production to onshore collection and treatment facilities. In this regard, the above complications in the operation of flow lines lead to potential hazards in the operation of underwater pipelines, which were analyzed in detail for the conditions of the Caspian Sea in [5].
Reducing risks in the operation of well flow lines and, in general, subsea pipelines, field process pipelines and other pipeline communications is directly related to the ability to diagnose their condition. It is important to note here that quite often, diagnostic work begins to be carried out after complications have arisen in their work and work to restore them requires significant costs. Therefore, issues of early diagnosis, that is, timely detection of the onset of complications, have always been of scientific and practical interest and remain relevant today.
For example, in article [6] the use of fractal analysis for diagnosing liquid inclusions in gas flows in field gas pipelines is justified. Based on field data, flow characteristics were constructed for the flow lines of selected wells and the corresponding values of the fractal dimension were obtained using the coating method. A stable correlation has been established between changes in fractal dimension and the presence of liquid inclusions in gas flows. The presence of such a stable connection was also confirmed by the results of studies conducted in [7].
Thus, a change in the fractal measure of flow characteristics curves seems to be a fairly effective analytical criterion for early diagnosis of complications in the operation of flow lines of wells, in particular the accumulation of the liquid phase in them.
II. Methods
As the object of research 23 flow lines of the "Bulla-Deniz" field (Azerbaijan) have been taken and dynamics of the change of average values of the following indices have been analyzed: oil consumption, gas consumption, pressure at the beginning and end of the line, gas factor, average temperature of the flow and productivity of the flow line. All these indices are presented in the
Table 1.
Studied lines were divided into two groups due to their productivity on the basis of hyperbolic value of distribution to reveal the flow lines in the operation of which complications occurred [8].
438
Ramiz Ismayilov, Ragiya Asgerova
RISK REDUCTION IN WELL FLOW LINES BASED...
RT&A, Special Issue № 6 (81), Part-1,
_________Volume 19, December 2024
Table 1: Values of operational parameters of the flow lines
Flow lines Diameter D, m Length L, m Rate of oil, qoil ,t/day cr> ПЗ ПЗ bO T5 Ч-ч ro О Ё CD -l-> № Si К a4 Pressure at the beginning P1 , MPa Pressure at the end P2 , MPa Gas factor q , m3/t Temperature t , °C Ourput of line t/day/MPa
9 0,102 1250 253 76 5,8 2,2 300 50 70,3
60 0,102 1500 462 72 7,2 2,2 156 45 92,4
67 0,102 1700 410 30 4,5 0,8 143 57 110,8
57 0,102 1500 285 25 6,3 4,2 88 58 135,7
65 0,102 1000 200 46 9,6 4,7 230 44 40,8
62 0,102 1800 150 28 4,4 2,0 187 43 62,5
61 0,102 1250 300 44 6,8 3,0 98 40 107,1
71 0,102 1250 385 44 5,8 2,0 114 47 101,3
34 0,102 1000 450 36 6,0 2,2 120 49 118,4
48 0,102 1250 210 45 3,9 1,9 110 38 105,0
43 0,102 1750 190 21 5,0 0,8 110 37 45,2
122 0,102 1200 181 80 7,0 2,0 442 35 36,2
100 0,102 1200 310 53 4,4 2,1 170 55 134,8
84 0,102 1350 220 22 5,1 2,0 100 45 70,9
80 0,102 1250 255 65 4,0 1,8 254 53 115,3
32 0,102 1500 250 47 3,5 0,9 188 53 96,1
45 0,102 1650 225 20 4,7 1,2 88 59 64,3
85 0,102 1750 150 40 4,9 3,5 266 35 107,0
76 0,102 1750 140 38 5,9 4,5 271 29 100,0
39 0,102 1500 60 6 3,7 2,3 100 54 42,8
36 0,102 1400 180 25 4,4 2,8 140 32 112,5
105 0,102 1300 320 39 6,4 3,9 310 42 94,1
17 0,102 1300 230 57 6,0 3,5 250 40 92,0
Flow lines with output below 92 t/day/MPa refer to the first group and above 92 t/day/MPa were collected to the second group. After division into groups we proceeded with big probability that complications have occurred in the lines with small productivity. That's why flow lines have been separately taken on each group: № 9, 65, 43 and 122 — from the first group line; № 61, 57 and 48 — from the second group line. Samples on monthly indices of oil consumption; gas factor and line productivity have been prepared individually. These indices have been processed for establishing static relations between existing methods of data analysis.
III. Results and discussion
The results of data processing have revealed definite regularity in the behavior of the dependence curves of flow line productivity on the gas factor. Thus, for the flow lines of the second group where no complications were observed (lines N 61, 57 and 48) gas factor weakly influences oil consumption change at the same pressure drops. By the other words points plotted on the coordinates of flow line productivity (qoil/AP,t/day/MPa) and gas factor index (q) are located on the straight line rather accurately (Figure, a). As it is seen from the figure increase of gas factor index doesn't considerably influence flow line productivity decreases. Together with it, analysis of dependency of productivity on the gas factor index for flow lines of the group (lines 9, 62, 43 and 122), where complications were observed has revealed the following stable regularity. In these lines productivity considerably decreases by the increase of gas factor (Fig. 1). It can be explained
439
Ramiz Ismayilov, Ragiya Asgerova
RISK REDUCTION IN WELL FLOW LINES BASED...
RT&A, Special Issue № 6 (81), Part-1,
_________Volume 19, December 2024
by that due to the complications occurred in the lines, oil consumption decreases, part of the gas dissolves in the sediments and as a result productivity of flow lines reduces.
a Line 57
Gas factor, m3/ton
b Line 122
250 300 350 400 450 500 550
Gas factor, m3/ton
Figure 1: The curves of the influence of the gas factor on the output of the flow lines
The result of the carried out researches allow us to determine the following main conclusion that considerable decrease the productivity by gas factor increase is the diagnostic criterion for early revealing of the occurrence of complications in the flow lines and carrying out recovery works in time.
References
[1] Lutoshkin G.S. Collection and preparation of oil, gas and water. Moscow, 2016.
[2] Rotov A.A., Istomin V.A., Cheltsova T.V., Mitnitsky R.A. Technology of liquid removal from gas collection network pipelines due to a short-term increase in gas extraction. // Gas industry. Special issue. No. 1 (782), 2019, pp. 86-92.
[3] Gurnitskaya E.Yu., Zubairov T.A. Analysis of the influence of the main complicating factors identified during operation in industrial pipeline transport // Transport and storage of oil products and hydrocarbon raw materials. No. 2-3, 2021, pp. 77-80.
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Ramiz Ismayilov, Ragiya Asgerova
RISK REDUCTION IN WELL FLOW LINES BASED...
RT&A, Special Issue № 6 (81), Part-1,
_________Volume 19, December 2024
[4] Hongfei Xu, Faisal Khan, Seungho Jung, Qingsheng Wang Probabilistic model for hydrate and wax risk assessment in oil and gas pipelines // Process Safety an Environmental Protection, 170 (2013), pp.11-18.
[5] Ismayilov R.A., Asgerova R.I., Ismayilov I., Guliyeva T. Risk assessment in subsea pipelines for the Caspian Sea conditions // RT&A, Special Issue No5(75), Volume 18, November 2023, pp.422-427.
[6] Ismayiov R.A., Askerova R.I., Fractal analysis for modes of the field pipelines / Readings of A.I. Bulatov: Materials of IV International scientific and practical conference. Conference bulletin, v.3, Krasnodar: Publishing House-South, 2020, pp.113-120.
[7] Ismayilov R.A., Bakhisheva Z.I. Fractal analysis of flow characteristics of delivery lines on the Karadag UGS // Proceedings of Azerbaijan High Technical Educational Institutions, Volume 25, Issue 4(144), 2023, pp.17-22.
[8] Edward L. Robinson Data analysis for scientists and Engineers. Princeton University Press. -2016, 408p.
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