Onshore developments

In the 1980s a series of serious incidents occurred in chemical plants throughout the world. With over 3500 fatalities, the Bhopal catastrophe of 1984 was the worst-ever industrial event in terms of loss of human life (although that event may well have been caused by sabotage). But there were many other high-profile incidents, including a sequence of explosions and fires in Pasadena, Texas in the mid to late 1980s. 

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As decommissioning approaches, enhanced recovery e.g. chemical flooding processes are often considered as a means of recovering a proportion of the hydrocarbons that remain after primary production. The economic viability of such techniques is very sensitive to the oil price, and whilst some are used in onshore developments they can rarely be justified offshore at current oil prices. 

MeGlashan, R. S. and Hviding, G., Troll Onshore Development Balaneing Costs, Energy Effieieney, and Emissions, 71st Annual GPA Convention, Anaheim, California, Mareh 1992. 

Not surprisingly, costs are several times higher than conventional wells. Nevertheless, overall project economics may favour ERD over other development options. For example, BP developed the offshore part of the Wytch Farm Oilfield (which is located under Poole Harbour in Dorset, UK) from an onshore location. The wells targeted the reservoir at a vertical depth of 1,500 meters with a lateral displacement of over 8,000 meters (Fig. 3.20). The alternative was to build a drilling location on an artificial island in Poole Bay. ERD probably saved a considerable amount of money and advanced first oil by several years. 

Whether on land or offshore, the principle of satellite development is the same. A new field is accessed with wells, and an export link is installed to the existing (host) facility. Development is not always easier on land, as environmental restrictions mean that some onshore fields have to be developed using directional drilling techniques (originally associated with offshore developments). A vertical well can be drilled offshore away from the host facility, and the well completed using a subsea wellhead. 

Dissolved Minerals. The most significant source of minerals for sustainable recovery may be ocean waters which contain nearly all the known elements in some degree of solution. Production of dissolved minerals from seawater is limited to fresh water, magnesium, magnesium compounds (qv), salt, bromine, and heavy water, ie, deuterium oxide. Considerable development of techniques for recovery of copper, gold, and uranium by solution or bacterial methods has been carried out in several countries for appHcation onshore. These methods are expected to be fully transferable to the marine environment (5). The potential for extraction of dissolved materials from naturally enriched sources, such as hydrothermal vents, may be high. 

In an attempt to stimulate onshore production of synthetic quartz and piezoelectric devices in the 1970s, Brazil imposed an embargo on exports and ultimately raised the price several-fold for small quartz crystals used as the starting material for quartz growth. However, sources of suitable pure quartz were located in the United States and Canada, including vein and pegmatic deposits (1). Synthetic processes compatible with the natural U.S. quartz starting material from a variety of sources were developed, and U.S. production became relatively independent of imports (1). 

Although the status of many 3D codes makes it possible to carry out detailed scenario calculations, further work is needed. This is particularly so for 1) development and verification of the porosity/distributed resistance model for explosion propagation in high density obstacle fields 2) improvement of the turbulent combustion model, and 3) development of a model for deflagration to detonation transition. More data are needed to enable verification of the model in high density geometries. This is particularly needed for onshore process plant geometries. 

The basic principles of rotary drilling defined for onshore operations are also applicable to offshore operations. The primary difference offshore is that a stable, self-contained platform must be provided for the drilling equipment. Communication with a well through possibly thousands of feet of water provides for mechanical as well as procedural differences, primarily in well control. Onshore technology can be applied to offshore operations in many instances on bottom-supported rigs, but the use of floating vessels has resulted in the development of new technology tailored to the offshore environment. 

Cathodic protection and associated instruments have developed in-line with the changing monitoring demands of both the onshore and offshore industries. In particular, for potential and current density measurements, far greater quantities of data are sought and are required to be processed into an easily assimilated form. Thus cathodic protection instrumentation has benefited from an increased association with microprocessor-based data handling and storage systems. 

Oil and Gas Production This sector is a major user of corrosion monitoring equipment, in particular for offshore fields where ramifications of corrosion and consequent maintenance are far more serious and costly compared with onshore production. Carbon steel is used for approximately 70-80 70 of production facilities. The development of a field is assessed on a defined corrosion risk which may not be correct, leading to serious corrosion. In addition, a reservoir may become more corrosive as the field is extracted owing to (a) increased water content, and (b) eventual souring of the field (hydrogen sulphide production). 

The methods of evacuation offshore are dependent on the ambient environmental conditions that may develop in the area and relative distance to the mainland. Regions that experience colder ambient conditions inhibit immersion opportunities and remote offshore locations retard onshore assistance capabilities. The preferred and most expedient evacuation means from an offshore installation is by helicopter. Because of the nature of fire and explosions to affect the vertical atmosphere surrounding an offshore installation, helicopter evacuation means cannot always be accommodated and should be considered of low probability where the accommodation quarters are located on the same structure as a hydrocarbon process. 

Wind energy Wind turbines capture the energy from the wind to produce electricity. They have been developed for various purposes, from large groups of grid-connected wind turbines, wind farms, both onshore and offshore, to very small autonomous turbines used for battery charging or in combined wind-diesel projects for off-grid application. 

Crude oil vapor pressure limitations for pipeline delivery may be comparable to those for tanker loading. However, a pipeline can be specifically designed as a high vapor pressure system to handle gas liquids components mixed with the crude oil, and it is quite possible that North Sea oil pipeline systems will be developed in this manner. It is not expected to be feasible to recover NGL components separate from oil and gas on the offshore platforms and construct separate NGL pipeline systems. It also may not be possible in every field to design a separation system which meets both gas specifications and low crude oil vapor pressure specifications unless an intermediate product is also made. This will be more fully discussed later In this paper. A high vapor pressure crude system will have an NGL separation and fractionation plant at the onshore pipeline terminal. The vapor pressure limitation for onshore crude deliveries will be fixed by TVP limitations at pump station suction conditions. 

In offshore operations, exploration wells are almost always plugged and abandoned even when they strike petroleum. Their sole function is to find oil or gas and to delineate the reservoir. The operator uses this information to pick a location for a permanent production platform from which development wells will be drilled to recover as much petroleum as economically possible. In onshore operations, however, successful exploration wells also become producers. 

The total investment will include 3600 million Euro allocated for the field development. This includes the sub sea well-stream pipeline system and the onshore processing plant and storage tanks. An other 700 million Euro will be invested in a LNG tanker fleet comprising 4 ships in the 140-145 000 m3 class [17]. The storage capacity of the Snohvit processing plant comprises two 125 000 m3 LNG storage tanks, one 45 000 m3 LPG tank and one 75 000 m3 condensate tank. 

During the last three decades, the Norwegian transportation system has been developed from a single pipeline system (Norpipe system) into a complex interconnected network, as shown in Figure 1. New transportation-and treatment capacity has gradually been added and the network comprises today rich and dry gas pipelines, compressor stations, riser platforms and two onshore gas treatment plants. The system is by now the world s most comprehensive integrated offshore gas transportation network. 

Abu Dhabi Company for Onshore Oil Operations Zakum Development Company (ZADCO)... 

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