Operations, Development and Strategies Employed Towards Optimizing the Gas Pipelines and Reducing Unnecessary Risk of Failures
Crude petroleum and natural gas are trapped in the earth’s crust by geological selectivity. These entrapments are in many cases far removed from the reservoir to the use points of the products. The necessity to move these products to their use points economically, efficiently, reliably, responsibly and safely has given rise to pipelines and pipeline network. In Nigeria, crude oil and natural gas are produced over vast area in the Niger delta region. The requirement of gathering these products for export at seaports and at refineries has generated a massive network of pipelines for crude oil and natural gas. A pipeline has been defined as a system of pipes for the transportation of liquid or gaseous phase, or even a combination of both phases, between well head facilities, production plants, pressure booting stations, processing plants or storage facilities. However, well head facilities, production plants, pressure-booting stations, processing plants or storage facilities are not considered as pipelines. A pipeline extends from one pig trap to another pig trap. The sections of pipelines crossing major rivers and estuaries, which cannot be constructed using land pipeline method, are treated as offshore pipelines (SIPM, 1993).
I.I GAS PIPELINE OBJECTIVE
The paramount objective of pipeline design and management is to select the pipeline dimensions and route, and its method of fabrication, installation and protection so that it can transport the specified product at an acceptable level of risk, whilst incurring minimum life cycle costs. Proper gas pipeline management is aimed at transmitting gas safely, efficiently, reliably, responsibly and profitably.
The gas such as Natural gas contains 83-93% methane, (CH4) so that it principal
Chemical constituents are carbon and hydrogen. Natural gas is usually found in the immediate vicinity of crude petroleum, although some natural gas wells do not yield oil. Natural gas is a non-renewable source of energy. It is a source of energy stored over time. Non renewable in the sense that, it is a form of potential energy that is not constantly and rapidly renewed for steady reliable use. Obviously, natural gas is constantly created but the rate of its geological formation in the soil is nothing to compare to its utilization by modern industries. Energy itself is simply defined as the ability to do work on another system.
Human utilization of energy, particularly fossil (coal, peat, crude petroleum and natural gas,) energy sources, has accelerated over time due to an increase in the human population and the discovery of technologies adopted for using the energy sources.
According to Parker: (1993), the acceleration is of exponential proportions and it came to be during the industrial revolution of the nineteenth and twentieth centuries. As the utilization of, and therefore the demand for, energy rose, scientists and engineers discovered ways to utilize new forms of energy. The availability and technical feasibility of many energy forms yielded a proliferation of energy choices, so that decisions had to be reached on the selection of energy sources. The need to make energy decisions has resulted in the development of an energy choice system. Fig.1 is the diagrammatic representation of an energy choice system. This system involves an economic analysis that compares the cost of input versus the benefit of output for specific energy sources. Among the factor included in this analysis are depletion cost, the cost of using non-renewable energy; social cost, the health and environmental issues; availability cost, the cost of utilizing energy sources subject to interruptions of supply; and switching or conversion costs, converting plant and equipment to energy uses.
Source: Sybil Parker (1993)
Natural gas may well be the most desirable of the entire chemical or mineral sources of energy because it can be piped directly to the customer. It does not usually require storage vessels at the user end, is clean-burning, requires no air-pollution control equipment (since it is assumed that it is already treated to remove H2S, CO2, Cl2 etc., before it gets to the ultimate user). It also produces no residual ash, and mixes readily with air to provide complete combustion at low excess air. This is quite unlike crude petroleum where the opposite is the case. The principal uses for natural gas are heating in residential and commercial buildings, industrial establishments, and for generating electric power.
The fluids transported in pipelines are as in Table 1, which are functions of their hazard potentials. This discussion has to do with fluid in category D, Natural Gas.
Table 1: 1 Categories of fluids at prevailing ambient temperature
|Categories of fluids at prevailing ambient temperature|
|Non flammable||Flammable||Non flammable||Flammable|
|Non Toxic||Toxic||Non Toxic||Toxic|
|Liquid ( water )||Liquid ( stabilized crude)||Gas ( N2, C02 )||Gas ( Natural gas, NH3)|
Source: ANSI/ASME B31.4/8
The relative analysis of fuels in terms of their emissions from combustion process also favours gas the choicest source of energy.
Table 1.2 Relative Emissions from burning Gas, oil, or Coal without control
|Sulphur (iv) oxide (SO2)||1||1000-3000||3000 – 8000|
|Nitrogen (v) oxide||1||2||4.5|
|Carbon (ii) oxide||1||1.5||1.5|
|Carbon (iv) oxide||1||1.25||1.7|
|Reactive Hydrocarbons||Virtually zero||2||1|
Source: SPDC-E: Natural Gas and NGL
The National Electric Power Authority (NEPA), in its training manual stated that the .raw material from which electricity is generated in a thermal power station is coal, oil, natural gas or natural uranium. Electricity, so generated is delivered to centers of consumption, through the transmission system. When coal, oil, or natural uranium is used the by-products will be ash, large volumes of fuel gases and/or irradiated uranium fuel elements; whose disposal is often a major factor for economic analysis. These considerations form the basis of site selection and location, and apply to the requirement of the site area and also to the facilities required in the locality (NEPA, 1999).
NEPA further wrote that the objectives of any aspect of power station design are to achieve the lowest capital cost and ease of combustion, together with simplicity and efficiency in the operation and maintenance of the station. In attempting to reach these objectives, a number of features have to be considered. These features are efficient operation: reliability, simplicity and safety of operation good working conditions and case of maintenance. The other is basically economic considerations namely low capital cost and minimum operating cost; which take into account simplicity in design, a good integrated design and a pleasing appearance. The objective of the initial design is to solve a completely integrated design considering the station as a single entity and not a collection of individual places of plants thrown together in haphazard manner. Gas power plants that use natural gas to develop its power has the following advantages over other types of power generating plants: lower capital, smaller site requirement, fewer and simpler auxiliaries controls, shorter time of erection and commissioning, quicker starting up and loading, easier maintenance, less vibration and low running. The pipeline through which the gas flows is the basis and most important part of the transmission facilities. It is made of steel, which is selected in accordance with proper codes and regulations and is usually welded together. Other pipelines and some small lines today are coupled together with threaded joints. The diameter of the pipe is determined by the amount of gas that is to be transported through the pipes, and the pressure of the gas determines the thickness.
SIPM (1993), has it that the risk and consequently, the problems associated with the management of pipelines, in terms of the safety of people, damage to the environment, and loss of income, depend on the expected failure frequency and the associated consequence. These are directly related to the type of fluids transported (here it is gas) and the sensitivity of locations or terrain differentials of the pipeline. In this context, pipeline failures are defined as loss of containment.
1.2 DESIGN CONSIDERATIONS
Mare (1985), stated that Pipeline design starts by fundamental planning of the potential pipeline route. Generally, pipeline design considerations are found in designing, environmental, constructional, and operations and maintenance of these pipelines:
i) Environmental requires the definition of current under-slides, and soil profiles, which could affect the stability and integrity of the pipeline during its economic life. The risk and problems critical to public safety and environmental protection should be reduced to as low as reasonably practicable, with the definite objective of preventing leaks, although, the severity is expected to change with time, and may likely to be on the increase as the pipeline ages.
ii) Designing refers to considerations in operating conditions, and requirements over its entire projected life cycle including final abandonment. That is, the maximum throughput and turn-down, the characteristics of fluids to be transported, the pressure and temperature requirements, the operations, the geographical location and the environmental conditions. These include the methods of analysis to be used, route guidelines, regulatory requirements and codes, allowable stresses and factors of safety. Economic considerations must include the costs of construction operation, surveillance, maintenance failure and repair. Furthermore, the potential effects of the pipeline on other systems must be fully explored for their economic, environmental and social effects, especially when they relate to a pipeline failure.
iii) Constructional factors include the equipment needed for fabrication and installation, the specification of the pipeline steels, welding and quality controls and pipeline bedding, backfill and armoring. Construction activities close to existing facilities should be planned in co-ordination with the operations functions, as shutdown of these facilities may be required.
iv) Operational and Maintenance must consider the need for tie-in points, flow rates, pressure and temperature profiles and the corrosiveness of the fluids to be transported, methods of pipeline surveillance and monitoring, the need for maintenance and possibly repair, means of controlling fluid escape and emergency procedures.
According to Allen: (1993), preventive maintenance is an absolute must for safety and protection. In order to be assured of reliable operation, pipelines must be checked on a very frequent schedule. The lives of the operating personnel and the general public may be jeopardized if these facilities are not in good operating condition at all times and the pipelines being protected is also endangered
Okon (I998), reported that until the early 1990s, pipeline maintenance in SPDC, for example, was on a breakdown basis- a line would be repaired only after a leak had occurred, re-qualified by pressure testing and restored into service. This approach contradicts the environmental practice, which demands, if possible, total elimination of negative impact of pipeline operations environment. This also has attendant cost of unbudgeted repairs, pollution clean-up and it tarnishes the reputation of the company.
SPDC (1996), reported that in 1995, SPDC management constituted a pipeline integrity task force to carry out a study into ways and means of restoring pipelines to their intended integrity including emergency (or intervention) and rehabilitation aspects. The major outcome of the task force finding was the need to have a single point responsibility for upgrade, repairs and intervention of pipeline operational status. This gave birth to Pipeline Integrity Management Department. This department executes all pipelines integrity requirements as previously handled by various Engineering and Production department.
Also, according to Ononogbu (1992), for gas pipeline reliability and management, the over view of the pipeline facilities are summarily taken. The pipeline integrity philosophy and policies, the accountability for the management of technical integrity and availability of pipelines are also periodically reviewed to meet current practice in the industry. Identified results of maintenance activity analysis, technical integrity audits, and efficiency test are built into activity plan and feedback is obtained.
1.4 OPERATING PHILOSOPHY
For the predicted life cycle conditions, a proper pipeline design should take due account of operations, inspection and maintenance requirements agreed in advance with the personnel responsible for the operation of the pipeline. These include integrity monitoring and maintenance of pipeline system, the requirements for telecommunication and remote operations, means of access to the onshore right of way (ROW), bypass at component which need regular maintenance etc.
SIPM (I991), summarily stated that the combined technical and management integrity of a pipeline is said to be achieved when under specified conditions, there is no foreseeable risk of failure endangering safety of personnel, environment or asset value. Even when there is deviation from this target, the management ensures rehabilitation and restoration of the pipeline system to the intended design integrity.
1.5 STATEMENT OF THE PROBLEM
In Nigeria, there has been a combination of factors that contribute to the growth of gas industries in the last decade. Such factors include the low prices for a superior fuel, assurance of continuing supply of gas by strict conservation practices and new discoveries. Prior to the current advent of environmental demands of totally eliminating where feasible, the negative impact of pipeline operations on the environment, precisely until 1990s, pipelines must fail before it is inspected, repaired and re-qualified for service.
According to Igwe (1986), Petroleum resources had consistently accounted for over 20% of Nigerian’s Gross Domestic Product (GDP), over 60% of government revenue over the years and over 85% of Nigeria’s foreign exchange earnings. This, undoubtedly, suggest that crude oil is the main stay of economic development in Nigeria. Therefore, the transmission lines must be able to deliver to the customer safely, economically and with integrity to facilitate growth and trust.
However, this growth and trust are stunted at the feet of improper management of resources-human and technical together with low gas market and price (controlled by government). The oil industry is fast growing on daily basis in size and technology. It is then required that all facilities like gas pipelines employed in this industry should also keep pace with this growth trend. Pipelines and facilities should be upgraded to meet with challenges that make their management worthwhile. The task therefore in this study is to investigate what has been done, things yet to be done and make recommendations.
1.6 PURPOSE OF STUDY
The purpose of this study includes the following:
(a) Identify the problems besetting gas pipelines.
(b) To assess the strategies adopted by prominent gas pipeline establishments in the
Management of the gas pipelines in Nigeria.
(c) To determine the impact of management strategies on the personnel, gas
Pipelines and the host communities and environment.
(d) Draw appropriate conclusions from the problems identified in (a) and examine
f) Make necessary recommendations.
1.7 RELEVANCE OF STUDY
Some lapses had been recorded over the years by gas pipeline firms as a consequence of neglect of duty in maintaining these gas pipelines. As a result of the sensitivity of the gases in the economy of Nigeria and its importance to the energy industry, high social risk level especially in terms of its inflammability, gas pipeline management therefore, calls for care. Also, in recognition of the importance of petroleum (gas) resources in Nigeria as singular largest revenue generator, proper planning and managing should be established right from the production of this gas through design to operational phases of the pipeline as a means of maintaining pipeline integrity and reliable gas supply. It is therefore, necessary to have an empirical study of the relationship existing among the design considerations (designing, construction, environmental, and operational and maintenance) of these gas pipelines. This will expose the present problems, management programmes, achievements and challenges in the field of gas pipelines management. At the moment the most threatening problems among others are leak and corrosion.
1.8 SCOPE OF STUDY
The title of the project essentially suggests a research work on firms in the Petroleum industry in Nigeria, like SPDC, Elf, Chevron, Mobile, NNPC etc. Most of the oil and gas is produced in the Niger Delta Region, presently defined by the political boundary of nine states – Abia, Akwa-Ibom, Bayelsa, Cross-River, Delta, Edo, Imo, Ondo and Rivers. The major focus will be on collection of data in the pipeline networks of Shell Petroleum Development Company (SPDC) in the Niger Delta area of Nigeria.
1.9 LIMITATION OF THE STUDY
The intention of this study is to have comparative analysis of all types of gases and their pipeline system in terms of their management in Nigeria but time, financial and other logistic constraints will not allow such elaborate research to be conducted. Rather, the research work will be examining the ways natural gas pipelines are managed in Nigeria. This work would answer questions on gas pipeline management as regards why, how, and when it affects the entire management and possibly other concerned parties.
Consequently, the study intends to look into the operations, development and strategies employed towards optimizing the gas pipelines and reducing unnecessary risk of failures.