**1. Articulation of issue**

Further development of the modern international community is going hand in hand with the intensive growth of fuel and energy raw materials consumption in all spheres of activity. Meanwhile, in the majority of on-land oil-and-gas regions, resources of oil and gas are exhausted and the possibilities of further increase of the discovered and usable economically recoverable reserves are complicated.

With this knowledge in mind, lately we can see special, increasing interest in a problem of the seas and oceans' oil and gas resources development [1, 2].

The gas and oil fields are discovered in 108 countries of the world. Ultimate reserves of gas reached 172 trillion cubic meters, of oil—172 billion tons; at the beginning of the twenty-first century, the world gas production was equal t0 2.6 trillion cubic meters, while oil production was 3.3 billion tons.

Initial recoverable hydrocarbon resources of the World Ocean continental shelf (up to 500 m isobathic line) and the inner continental shelf are estimated equal approx. to 370 billion tons of fuel oil equivalent (TFOE), including more than 200 trillion cubic meters of free gas and about 155 billion tons of oil and condensate.

The primal gas resources in water areas are concentrated within the shelf of the Northern Asia—44.5 trillion cubic meters. Its bigger part is located offshore in the Kara Sea. Offshore gas resources of Eastern Europe, North and South America and the Middle East are also comparable and considerable relative to ones in Northern Asia (21–24 trillion cubic meters).

In the world, since the 1940s, the multiple sea platforms (SP) are engineered and operated with a wide range of parameters and are used for offshore petroleum and gas production. The largest of them are five platforms of the USA, Norway and Russia. They provide production at sea depths up to 2.5 km and well-drilling up to 10–13 km. About 10 platforms are in operation in Russia: on Caspian, Okhotsk seas and on the seas of the Arctic Ocean. The most significant of them are the platforms "Piltun-Astokhskaya-A (former Molikpak)," "Piltun-Astokhskaya-B," "Lunskaya-A," "Orlan," "Berkut" and "Prirazlomnaya" (**Figure 1**). Length of already constructed offshore pipelines is about 300 km. In long term, the need of Russia in offshore projects includes the necessity to provide functioning of about 50 SPs.

In the world history of development of the continental shelf, a number of disasters and serious accidents with catastrophic consequences occurred due to lack of attention to measures for identification and mitigation of threats for safe operation is wrote. The 15 most dramatic accidents on drilling vessels and platforms of various types (semisubmersible, submersible, mobile, stationary) happened during the last 40 years were followed by:

• great loss of lives (up to 164 people) occurred due to limited space on the platform, evacuation difficulties and vulnerability of personnel to thermal fire impact and toxic effects caused by combustion products;

60 billion dollars; the direct economic loss suffered from flooding of the "Kol'skaya

Review of accidents with catastrophic consequences (death of great number of people, large-scale ecological contamination or material losses) occurred on oil and gas production platforms demonstrate reduction in number during recent years. This can be explained by the platforms' technological and design performance

Evaluation of information about accidents and disasters occurred on offshore drilling rigs of various types makes it possible to combine and classify all accidents in accordance with major, internally connected accidents sources (**Figure 3**):

(Kola)" platform (Russia) is about 200 million dollars.

*Disasters of large scale platforms in USA (a) and Russia (b).*

**Figure 1.**

**Figure 2.**

**75**

*Large offshore platforms in Russia.*

improvements and application of modern safety systems (**Figure 2**).

*Hybrid Modeling of Offshore Platforms' Stress-Deformed and Limit States…*

*DOI: http://dx.doi.org/10.5772/intechopen.88894*


Most economic direct loss suffered after the disaster on the platform in the Gulf of Mexico (USA) and was more than 20 billion dollars, while indirect losses reached *Hybrid Modeling of Offshore Platforms' Stress-Deformed and Limit States… DOI: http://dx.doi.org/10.5772/intechopen.88894*

**Figure 1.** *Large offshore platforms in Russia.*

#### **Figure 2.**

**1. Articulation of issue**

*Probability, Combinatorics and Control*

condensate.

50 SPs.

**74**

Asia (21–24 trillion cubic meters).

the last 40 years were followed by:

Further development of the modern international community is going hand in hand with the intensive growth of fuel and energy raw materials consumption in all spheres of activity. Meanwhile, in the majority of on-land oil-and-gas regions, resources of oil and gas are exhausted and the possibilities of further increase of the

With this knowledge in mind, lately we can see special, increasing interest in a

The gas and oil fields are discovered in 108 countries of the world. Ultimate reserves of gas reached 172 trillion cubic meters, of oil—172 billion tons; at the beginning of the twenty-first century, the world gas production was equal t0 2.6

Initial recoverable hydrocarbon resources of the World Ocean continental

estimated equal approx. to 370 billion tons of fuel oil equivalent (TFOE), including more than 200 trillion cubic meters of free gas and about 155 billion tons of oil and

The primal gas resources in water areas are concentrated within the shelf of the Northern Asia—44.5 trillion cubic meters. Its bigger part is located offshore in the Kara Sea. Offshore gas resources of Eastern Europe, North and South America and the Middle East are also comparable and considerable relative to ones in Northern

In the world, since the 1940s, the multiple sea platforms (SP) are engineered and operated with a wide range of parameters and are used for offshore petroleum and gas production. The largest of them are five platforms of the USA, Norway and Russia. They provide production at sea depths up to 2.5 km and well-drilling up to 10–13 km. About 10 platforms are in operation in Russia: on Caspian, Okhotsk seas and on the seas of the Arctic Ocean. The most significant of them are the platforms

discovered and usable economically recoverable reserves are complicated.

problem of the seas and oceans' oil and gas resources development [1, 2].

trillion cubic meters, while oil production was 3.3 billion tons.

shelf (up to 500 m isobathic line) and the inner continental shelf are

"Piltun-Astokhskaya-A (former Molikpak)," "Piltun-Astokhskaya-B," "Lunskaya-A," "Orlan," "Berkut" and "Prirazlomnaya" (**Figure 1**). Length of already constructed offshore pipelines is about 300 km. In long term, the need of Russia in offshore projects includes the necessity to provide functioning of about

In the world history of development of the continental shelf, a number of disasters and serious accidents with catastrophic consequences occurred due to lack of attention to measures for identification and mitigation of threats for safe operation is wrote. The 15 most dramatic accidents on drilling vessels and platforms of various types (semisubmersible, submersible, mobile, stationary) happened during

• great loss of lives (up to 164 people) occurred due to limited space on the platform, evacuation difficulties and vulnerability of personnel to thermal fire

Most economic direct loss suffered after the disaster on the platform in the Gulf of Mexico (USA) and was more than 20 billion dollars, while indirect losses reached

impact and toxic effects caused by combustion products;

• infilling and destruction of platforms infrastructure;

• offshore areas and airspace pollution; and

• vegetal and animal life demise.

*Disasters of large scale platforms in USA (a) and Russia (b).*

60 billion dollars; the direct economic loss suffered from flooding of the "Kol'skaya (Kola)" platform (Russia) is about 200 million dollars.

Review of accidents with catastrophic consequences (death of great number of people, large-scale ecological contamination or material losses) occurred on oil and gas production platforms demonstrate reduction in number during recent years. This can be explained by the platforms' technological and design performance improvements and application of modern safety systems (**Figure 2**).

Evaluation of information about accidents and disasters occurred on offshore drilling rigs of various types makes it possible to combine and classify all accidents in accordance with major, internally connected accidents sources (**Figure 3**):

parameters R(t)—probabilities of occurrence of P(t) negative processes and events (dangers, challenges, threats, crises, disasters and accidents) and

*Hybrid Modeling of Offshore Platforms' Stress-Deformed and Limit States…*

• identification of negative events scenarios with regard to a complex system and quantitative risk assessment R(t) through parameters of main triggering and affecting factors—dangerous energies E(t), substances W(t) and information

On the basis of Eqs. (1)–(5), categorization of emergency situations, high-risk objects and dangerous processes in terms of risks R(t) is developed. Objectively, the norm settings, regulation and control in the area of safety provision as per safety and security major components (i.e., social and economic, military, scientific and technical, industrial, environmental and demographic) when using risks nominally

The [*R*(*t*)] value is set and defined by bodies of the highest public administration with consideration of abilities and the capacity of the country, level of scientific justifications and domestic and international experience. The realization of the requirement (6) [1–3] will be provided proceeding from the position that the

• individual risks (1 per year) of life and health loss caused by abovementioned

processes and events that are taking into account vulnerability of social *(N)*,

The economic damages due to loss of lives and human health and environmental and technical infrastructure damages are included in the economic risks R(t). Scientific justification of acceptable risks [R(t)] includes development of methodology of definition of critical (limiting, inadmissible) risks Rc (t) and fixing of risks

> *Rc*ð Þ*t nR*

(7)

• economical risks (rubles per year, dollars per year) caused by negative

½ �¼ *Rc*ð Þ*t*

For quantitative assessment of value of risks Rc (t) relevant to accidents and disasters on SP all basic, Eqs. (1)–(7) can be used while the value of risks margin *nR* shall be greater than unity (*nR* ≥ 1). Considering the best domestic and foreign practices, the variation for risks margin can be rather wide (2 ≤ *nR* ≤ 10) at the

natural *(S)* and technogenic *(Т)* areas according to Eqs. (1)–(4).

*R t*ðÞ¼ *FR*f g *P t*ð Þ, *U t*ð Þ (2)

*P t*ðÞ¼ *FP*f g *RN*ð Þ*t* , *RS*ð Þ*t* , *RT*ð Þ*t* (3)

*U t*ðÞ¼ *FU*f g *UN*ð Þ*t* , *US*ð Þ*t* , *UT*ð Þ*t* (4)

*R t*ðÞ¼ *FR*f g *E t*ð Þ,*W t*ð Þ,*I t*ð Þ *:* (5)

*R t*ð Þ ≤ ½ � *R t*ð Þ , (6)

consequential losses U(t)

*DOI: http://dx.doi.org/10.5772/intechopen.88894*

flows I (t)

comes down to ratio

margin *nR* in the form of

beginning.

**77**

where [*R*(*t*)] is acceptable risks level.

defining risks of R(t) are two groups of risks:

negative processes and events; and

**Figure 3.** *Characteristic of accidents on oil and gas production platforms.*

uncontrolled release of oil and/or gas from the well; damage of integrity of load bearing (or supporting) structures, as well as equipment failing (or malfunctioning); personnel mistakes; external impacts of technogenic (man-induced) nature (allisions with seagoing vessels, helicopters fall, subversive actions); and off-design impacts of the natural environment.

The probability of accident that may occur during a year on the Unit is in the range from 8 � <sup>10</sup>�<sup>5</sup> up to 1.6 � <sup>10</sup>�<sup>3</sup> per year, and this conclusion is based on the data in the Declaration of Industrial Safety for four Russian production platforms and nine floating drilling rigs.
