Файл: Томский политехнический университет школа Инженерная школа природных ресурсов Направление подготовки.pdf

86
«Научнотехнический центр исследований проблем промышленной безопасности», 2013. – 288 с.
22. ГОСТ
12.1.012-90 ССБТ. Вибрационная безопасность. Общие требования. Стандартинформ, 1990. – 20 с.
23. Федеральные нормы и правила в области промышленной безопасности
«Правила промышленной безопасности опасных производственных объектов, на которых используется оборудование, работающее под избыточным давлением». — М.: Закрытое акционерное общество
«Научнотехнический центр исследований проблем промышленной безопасности», 2014. – 254 с.
24. Трудовой Кодекс – ТК РФ – Глава 47. Особенности регулирования труда лиц, работающих вахтовым методом.

87
Приложение А
Рисунок 25 – Факт выполнения программы геолого-технических мероприятий за 2019 год на базовом фонде скважин
48,9
90,1
86,3
144,3
16,9
49,5
9
47,6
6,1
3,4
68,7
35,5
58,9
81,6
98,7
58,5
27
19
24
24
9
20
25
1
8
1
4
10
14
17
16
6
19
44
57
77
13
46
2
242
9
76
83
54
27
37
50
218
0 50 100 150 200 250 300 0
20 40 60 80 100 120 140 160
план факт план факт план факт план факт план факт план факт план факт план факт
С
ре
дн
и
й
п
ри
рос
т,
т
/с
ут
К
ол
и
че
ст
во
ск
ва
ж
и
н
, ш
т
Д
оп
. д
обы
ча
, т
ы
с.
т.
Доп. добыча, тыс.т.
Количество скважин
Средний прирост, т/сут
ГРП
Оптимизиция

ОПЗ при КРС
ЛА
РИР
ПВЛГ+ДП
ВБД
ПМД

88
Приложение Б
(справочное)
EFFICIENCY ANALYSIS OF APPLIED WELL INTERVENTION TECHNIQUES
AT EASTERN SIBERIA FIELDS
Студент
Группа
ФИО
Подпись
Дата
2БМ83
Шупиков Александр Александрович
02.03.2020
Руководитель ВКР
Должность
ФИО
Ученая степень,
звание
Подпись
Дата
Доцент
Цибульникова
Маргарита Радиевна к.г.н.
02.03.2020
Консультант – лингвист отделения иностранных языков ШБИН:
Должность
ФИО
Ученая степень,
звание
Подпись
Дата
Старший преподаватель
Миронова Вероника
Евгеньевна
02.03.2020

89
Introduction
A well intervention, or well work, is any operation carried out on an oil or gas well during, or at the end of, its productive life that alters the state of the well or well geometry, provides well diagnostics, or manages the production of the well [1].
Most well interventions are remedial operations performed on producing wells with the intention of restoring or increasing production. A well may require intervention due to flow restrictions, changes in reservoir characteristics, sand production, mechanical failure, or access additional hydrocarbon pay zones. Downhole applications that are performed during well interventions include well surveillance and diagnostics, implementation of reservoir management techniques, completion repair and re-entry drilling to reach new producing intervals.
In well intervention, downhole applications are performed in the wellbore to remedy production problems or otherwise increase production from the well. Most of these applications are typically a less complex version of well construction and completion phase work.
The frequency of well intervention that will be performed during the life of a field is difficult to predict, since the decision to intervene in a well is dependent on numerous variables, including reservoir characteristics, infrastructure and economic considerations [2]. Stimulation and remedial cementing/conformance applications are the most frequent reasons for well intervention. It is interesting to note that well intervention is most often performed to address reservoir specific issues, rather than to repair downhole mechanical equipment and completions.
Well intervention has various advantages including the opportunity to:

Operate more efficiently.

Solve more unforeseen problems easily.

Rejuvenate production.

Make informed decisions with access to critical data.

Reduce risk and non-productive time (NPT).

Boost ROI while reducing cost.

90
Well intervention is qualitatively different from other measures at oil wells, since as a result of its implementation, there may be an increase in oil production. Oil- producing enterprises ensure the implementation of project indicators of field development using well intervention techniques.
Well interventions are carried out at all stages of field development. But most intensively – in the later stages. In mature fields with declining production and increasing waterlogging, well intervention is particularly important.
Selection of effective well intervention techniques at each oil field is one of the main tasks of the company's geological service. The well intervention events are planned annually when preparing the business plan of the oil-producing enterprise. And then they are updated and adjusted monthly.
The well intervention classification is quite broad. There are such measures as:

bottom-hole formation zone treatment,

commingling of the layers,

removal of salt deposits,

optimization of the well operation,

removal of heavy oil deposits,

changing the methods of operation,

decommissioning, etc.
At the same time, the methods of conducting each type of well intervention are also divided into categories depending on the methods used.
The most commonly used methods are fracturing, bottom-hole formation zone treatment, repair-insulation works and side-tracking.
Fracturing
Fracturing is used to simplify the extraction of oil and natural gas in porous and permeable rock by stimulating the flow of the fluid.[3] Since unconventional oil and natural gas are often trapped inside porous rocks with low permeability, such as shale, pathways must be manually created for the fluids to flow through the rock and into the well [3]. Before the widespread use of hydraulic fracturing, drilling companies would

91 drill several wells into the rock to release the oil and gas trapped inside. However, this method is not efficient as the wells are still not able to cover a large volume of the rock.
Hydraulic fracturing is a solution to this problem, and is done after the drilling process.
Figure 1 – Diagram of a fractured well.
To fracture the well, a fluid known as fracking fluid is pumped into a wellbore, creating enough pressure to fracture the rock. Because fracking is a process used for wells that have already been drilled, it can be used from right after the well has been drilled, or to revitalize an old well. Generally, these wells are drilled directionally or horizontally to further increase the surface area of the rock containing the oil or gas that the wellbore touches. This fluid consists of mostly water containing chemicals and sand, although the specific type and quantity of these chemicals can vary. The sand in the fluid is known as a "proppant" that holds the cracks formed open for the oil or gas to escape [3].

92
The injection of this fluid breaks a small amount of the rock that surrounds each well. Then it increases the volume of rock that gas or oil can be extracted from by increasing the number of small fissures in the rock.
Hydraulic fracturing is an extremely efficient process that allows for better extraction of natural gas and oil. The biggest environmental problem is the actual combustion of the natural gas, which leads to increased levels of carbon dioxide in the atmosphere. Hydraulic fracturing is one of the techniques that are allowing humans to extract more carbon from the crust of the planet and change the climate.
In terms of resource extraction, as with any method of material extraction, there are several environmental concerns that are associated with it. Mainly, the concerns involve the amount of water required to fracture a well, along with water contamination from potentially harmful chemicals in the fracturing fluid. Some argue that seismic disruption is a potential but unproven side-effect. In addition to the negative side- effects of fracturing, there are also potential benefits. One benefit is the reduced above ground area needed to extract oil from a rock. Before fracturing began to be used, a large number of surface wells needed to be dug to access oil or gas [4].
The bottom-hole formation zone treatment
The bottom-hole formation zone treatment is the most widely used type of
GTM. There are a great many technologies for influencing the bottom-hole formation zone. Most often, treatment is carried out with various acidic compositions. For carbonate reservoirs and reservoirs with a high content of carbonate cement, the most commonly used injection of acid compositions is based on hydrochloric acid. For terrigenous reservoirs – injection of acid compositions based on hydrofluoric acid.
Stages of well acid treatment are shown in figure 2.
The bottom-hole formation zone treatment is carried out at all stages of oil field development to restore and improve the filtration characteristics of the bottom-hole zone of the formation in order to increase the productivity of producing and pumping wells.
The choice of the bottom-hole formation zone treatment method is based on the study of the causes of low wells productivity. It is necessary to take into account the

93 physical and chemical properties of reservoir rocks and the fluids that saturate them, as well as special hydrodynamic and geophysical studies to assess the filtration characteristics of the bottom-hole formation zone.
Figure 2 – Stages of well acid treatment
The bottom-hole formation zone treatment results in the following:

improvement of lithological bottom-hole formation properties as a result of heat treatment and creation of pressure impulse attributing to the removal of asphaltic tar paraffin depositions (ATPD) and fracture formation.

oil viscosity decrease resulted from heat effect and monofuel thermolysis products;

lowering of surface tension at the interface of displaced and displacing fluids and improvement of rock surface wettability.

decomposition of chemical agents under the temperature effect producing gases and other substances which increase displacement efficiency;

94

formation of water-, gas-and-oil emulsions and foam systems in highly permeable zones resulting in leveling the displacement front and increasing involvement of heterogenous formations into the oil recovery process [5].
The repair-insulation works
The repair-insulation works are carried out in order to eliminate leaks in the production column and limit water flow to the well. Tht repair-insulation works can be performed with various materials (cement, liquid glass), patch installation, or packers
(for example two-packer arrangements). The peculiarity of this type of well intervention techniques is that the effectiveness of the work carried out is rather not in obtaining additional oil production, but in reducing the water content in the well production.
Technological scheme of carrying out the repair-insulation works is shown in figure 3.
Figure 3 – Technological scheme of carrying out the repair-insulation works
The repair-insulation works wells are carried out in cases where it is necessary to:

ensure isolation of productive facilities from water;

create a cement cup at the bottom of a well or a cement bridge in a column;

lock the filter when transferring the well to a higher or lower horizon;

create a cement belt in the bottom-hole zone of the well for reliable isolation;

95

cover defects in the service column;

isolate the productive horizons from each other in the interval of descent of the production column or shank when cutting and drilling the second shaft;

secure the bottom-hole area of the well to reduce corking.
The main requirement for the technology is to ensure that working solutions of the insulating agent are injected into the well and pushed into the insulated interval.
It s is achieved by excluding from the technology conditions and operations that contribute to dilution of working solutions, as a result of filling the well with a homogeneous liquid density; the use of working solutions with a density greater than that of the liquid in the well; the use of drilling packers.
The side-tracking
The side-tracking from existing wells is an effective way to overhaul and reconstruct wells. The technology is particularly effective for fields at a late stage of development.
Previously untapped areas of the reservoir and hard-to-recover oil reserves, production of which was not previously possible, are involved in the development by drilling side shafts. The use of the side-tracking technology increases oil recovery and actually replaces well compaction. Appropriate technologies help to preserve the well and save the cost of developing the well. Moreover, the operation of the side-tracking is effective for all types of deposits.
Choosing a specific type of the well interventions for a particular well is a non- trivial task because there are several options for its solution. It should be taken into account that any unjustified interference of this kind in the operation of the well can lead to economic losses, which are calculated by the cost of carrying out the event and the lost profit.
A comprehensive approach to the well interventions planning allows us to solve problems of improving the efficiency of field development.
The selection of candidate wells for a certain type of the well intervention is conducted in accordance with the stages of system analysis of problem situations:

96 1. Situation analysis (identification of the need to the well interventions for a specific well).
2. Setting goals (defining parameters according to which the well interventions should be directed).
3. Development of solutions and analysis of alternatives (formation of a list of possible types of well interventions to achieve the goals, assessment of their effectiveness).
4. Implementation of the decision (holding the well intervention).
5. Evaluation of results (monitoring wells after the well intervention, analysis of results).
The process of forming the GTM program is individual for each field.
Depending on the geological features of the field, certain types of measures are selected according to maximum effect of predicted additional oil production.
It is necessary to collect and analyze a sufficiently large amount of source data for the selection of well intervention. They can be divided into three groups: geological, technological and technical.
Geologic maps include:

initial oil-saturated thickness

residual oil-saturated thickness;

permeabilities;

current saturation and forecasting the water content;

oil and water filtration circuits.
Well data (technological) includes:

interpretation results of geophysical well surveys;

well trajectories;

database of perforations;

technological regimes and monthly operational reports throughout history;

coordinates of reservoir intersections;

results of compensation for production by waterflood elements injection;

97

PVT-properties, modified relative phase permeabilities, reservoir reference.
Data on the technical condition of the wells:

information on field geophysical surveys on leakage of production casing, annular circulation, watering sources;

non-working / emergency fund;

state of the bottom-hole.
The first step in the formation of the geological and technical measures complex is to analyze the operation parameters of all wells in the current mode, from which wells with a decrease in production level are identified. Further, by factor analysis, the values and causes of the decrease in oil production are determined:

due to reservoir pressure;

bottomhole pressure;

decrease in productivity;

water cut changes.
In production wells, it is important to prevent the bottomhole pressure from falling below the saturation pressure, since then oil degasses and the homogeneous fluid decomposes into gaseous, liquid and solid phases. Scale intensification, premature failure of pumping equipment and leading watering occur, and as a result, the oil productivity coefficient of the well decreases.
A decrease in the well productivity coefficient indicates a difficult filtration of the formation fluid near the bottom of the well.
The decrease in permeability of the bottom-hole formation zone occurs as a result of the following factors:

well operation is accompanied by a violation of thermobaric balance in the near-wellbore zone, which leads to the release of dissolved gas from oil, deposition of paraffin, clogging the pore space;

the bottom-hole zone is substantially contaminated during the overhaul in the wells as a result of the penetration of the kill fluid;

98

the influx of oil into the well is accompanied by the removal of sand from the bottomhole zone and the formation of sand plugs overlapping the well filter;

it is also possible to single out biological factors causing contamination of the bottom-hole zone with the waste products of microorganisms and bacteria.
Due to the fact that the produced water at the deposits is supersaturated with sodium chloride, calcium carbonate and calcium sulfate, it leads to more intensive deposition of gypsum, halite and calcite in the bottomhole formation zone.
Therefore, the planning of measures for processing the bottom-hole zone of the formation should include the implementation of technology for controlling scaling.
It is necessary to determine the amount of additional oil production from the well intervention to assess technological efficiency. There are a number of methods for it, based on a comparison of the base (forecast) and factual oil production from the well at the end of the calculation period. This difference determines the amount of additional oil production.
Basic production is calculated by the displacement characteristics that are most suitable for these conditions of the development of the facility (maximum convergence with the real data of the facility). On the other hand, the assessment of technological efficiency should be related to the forecasting of production for the future period, since the efficiency of the well interventions is planned, as well. Planning for oil production or planning for additional oil production and assessment of the technological efficiency of the geological and technical measures should be carried out by means of the same methods.
Much attention should be paid to the issues of separating the effects associated with conducting well intervention and the effects connected with changes in conditions during normal operation (shutting down or putting in wells, changing the rate of production or injection of liquid, etc.). A correct solution to this problem is possible when combining the integral description of the considered area (based on the displacement characteristics) with the analysis of the impact of the well intervention on the technological parameters of the wells.

99
The technological efficiency of the well intervention is characterized by several quantitative indicators (criteria):

additional oil production;

increase in selection rates;

reduction in the volume of produced water.
The question of efficiency in selecting the type of the well interventions is one of the foundations of the feasibility of oil production.
Wells are divided by the degree of reaction to the work performed in order to assess the effectiveness of the well interventions.
If a positive effect or additional oil production is obtained, the well is considered to have reacted. A well with a negative effect is considered not to have reacted to the impact.
The approach that evaluates only positively reacted wells is used in practice.
The following principle is used to evaluate the effectiveness of the well intervention: if a single production well has a positive effect, its duration is calculated until the actual oil production falls below the baseline; if the well has a negative effect immediately after the well intervention, the calculation of the effect is discontinued.
REFERENCES
1. Well intervention
[Online].
Available: https://en.wikipedia.org/wiki/Well_intervention.
2. Sandeep Khurana, Brad DeWalt, Colin Headworth. Well intervention using rigless techniques // Offshore Technology Conference, 5-8 May, Houston, Texas. – 2003.
– P. 13.
3. Alberta Energy Regulator. (July 2, 2015). Hydraulic Fracturing [Online].
Available: https://www.aer.ca/about-aer/spotlight-on/unconventional-regulatory- framework/what-is-hydraulic-fracturing.
4. Energy Education. (August 29, 2017). Hydraulic Fracturing [Online]. Available: https://energyeducation.ca/encyclopedia/Hydraulic_fracturing.

100 5. V. Graifer, V. Kokorev, G. Orlov, K. Bugaev. Bottom-hole formation zone treatment using monofuel thermolysis // SPE Russian Oil and Gas Conference and
Exhibition. – 2003. – P. 26-28.