Facilities, surface

The field development plan s prime purpose is to serve as a conceptual project specification for subsurface and surface facilities, and the operational and maintenance philosophy required to support a proposal for the required investments. It should give management and shareholders confidence that all aspects of the project have been... 

While the long chain hydrocarbons (above 18 carbon atoms) may exist in solution at reservoir temperature and pressure, they can solidify at the lower temperatures and pressures experienced in surface facilities, or even in the tubing. The fraction of the longer chain hydrocarbons in the crude oil are therefore of particular interest to process engineers, who will typically require a detailed laboratory analysis of the crude oil oomposition, extending to the measurement of the fraction of molecules as long as C3Q. 

As the conditions of pressure and temperature vary, the phases in which hydrocarbons exist, and the composition of the phases may change. It is necessary to understand the initial condition of fluids to be able to calculate surface volumes represented by subsurface hydrocarbons. It is also necessary to be able to predict phase changes as the temperature and pressure vary both in the reservoir and as the fluids pass through the surface facilities, so that the appropriate subsurface and surface development plans can be made. 

In addition, the separator temperature and pressure of the surface facilities are typically outside the two-phase envelope, so that no liquids form during separation. This makes the prediction of the produced fluids during development very simple, and gas sales contracts can be agreed with the confidence that the fluid composition will remain constant during field life in the case of a dry gas. 

Oil viscosity is an important parameter required in predicting the fluid flow, both in the reservoir and in surface facilities, since the viscosity is a determinant of the velocity with which the fluid will flow under a given pressure drop. Oil viscosity is significantly greater than that of gas (typically 0.2 to 50 cP compared to 0.01 to 0.05 cP under reservoir conditions). 

The collection of representative reservoir fluid samples is important in order to establish the PVT properties - phase envelope, bubble point, Rg, B, and the physical properties - composition, density, viscosity. These values are used to determine the initial volumes of fluid in place in stock tank volumes, the flow properties of the fluid both in the reservoir and through the surface facilities, and to identify any components which may require special treatment, such as sulphur compounds. 

Introduction and Commercial Application The reservoir and well behaviour under dynamic conditions are key parameters in determining what fraction of the hydrocarbons initially in place will be produced to surface over the lifetime of the field, at what rates they will be produced, and which unwanted fluids such as water are also produced. This behaviour will therefore dictate the revenue stream which the development will generate through sales of the hydrocarbons. The reservoir and well performance are linked to the surface development plan, and cannot be considered in isolation different subsurface development plans will demand different surface facilities. The prediction of reservoir and well behaviour are therefore crucial components of field development planning, as well as playing a major role in reservoir management during production. 

The most reliable way of generating production profiles, and investigating the sensitivity to well location, perforation interval, surface facilities constraints, etc., is through reservoir simulation. 

The wells provide the conduit for production from the reservoir to the surface, and are therefore the key link between the reservoir and surface facilities. The type and number of wells required for development will dictate the drilling facilities needed, and the operating pressures of the wells will influence the design of the production facilities. The application of horizontal or multi-lateral wells may where appropriate greatly reduce the number of wells required, which in time will have an impact on the cost of development. 

The type of development, type and number of development wells, recovery factor and production profile are all inter-linked. Their dependency may be estimated using the above approach, but lends itself to the techniques of reservoir simulation introduced in Section 8.4. There is never an obvious single development plan for a field, and the optimum plan also involves the cost of the surface facilities required. The decision as to which development plan is the best is usually based on the economic criterion of profitability. Figure 9.1 represents a series of calculations, aimed at determining the optimum development plan (the one with the highest net present value, as defined in Section 13). 

In gas field development, the recovery factor is largely determined by how low a reservoir pressure can be achieved before finally reaching the abandonment pressure. As the reservoir pressure declines, it is therefore common to install compression facilities at the surface to pump the gas from the wellhead through the surface facilities to the delivery point. This compression may be installed in stages through the field lifetime. 

Some of the approaches and techniques for measuring performance and managing the constraints of the subsurface and surface facilities, and the internal and external factors will be discussed in this section. 

The purpose of the surface facilities is to deliver saleable hydrocarbons from the wellhead to the customer, on time, to specification, in a safe and environmentally acceptable manner. The main functions of the surface facilities are... 

The surface facilities used to perform these functions are discussed in Section 10.1, and are installed as a sequence or train of vessels, valves, pipes, tanks etc. This section... 

A natural gas reservoir which remains in a one-phase state as it is depleted (no condensation in the reservoir), but from which liquids can be commercially recovered in surface facilities. 

Eight months after injection began in the second injection well, wastes had leaked upward into the adjacent shallow monitoring well. The leak apparently was caused by the dissolution of the cement grout around the casing. In June 1972,13 months after injection began in the second well, the waste front reached the deep monitoring well located 450 m (1500 ft) northwest of the injection well. Waste injection ended in December 1972. As of 1977, the wastes were treated in a surface facility.170... 

Major disincentives to enhanced oil recovery are the lack of tax incentives and a substantial decline in the price of oil since the end of 1981. All the investment in new wells and surface facilities and injectants must take place before any incremental oil is produced. 

Petrologic and SEM analyses of these clay samples reveal micro-textural and structural features and mineral association suggesting that they deposited directly from the brine in the surface facilities, and are not hydrothermal alteration minerals transported from production wells. 

Storage of C02. These costs are strongly determined by the number and depth of wells required for underground storage and the operation of the necessary surface facilities. 

The Western Operating Area (WOA) contains three oil Gathering CenterE (DCs) each capable of processing 300,000 BPD <2000m3/h) oil and 480 MMSCFD (S86,OOOm3/h) gas. There are 17 remote well pads connected to the GCs by the surface flowlines. The wells are directionally drilled from the well pads there may be up to 30 wells per well pad. Figure 1 shows the relative locations of the surface facilities. 

Consider a black oil at a reservoir pressure above the bubble point. Production into the wellbore will consist solely of liquid. During the trip to the surface and through surface equipment to the stock tank, the dissolved gas will come out of solution. This gas will appear as separator gas and stock-tank vent gas. Typical surface facilities for a black oil are shown in Figure 13-1. 

Low-hazard waste any nonexempt waste that is generally acceptable for disposal in a dedicated near-surface facility for hazardous wastes. 

Most low-level waste, except high-activity, longer-lived waste that is anticipated to be produced in small volumes, is intended for disposal in a near-surface facility. The acceptability of near-surface disposal for most low-level waste is based primarily on assessments of the long-term performance of such facilities, which indicate that the health risks to the public, including future inadvertent intruders, should be acceptable. 

All wastes classified as hazardous under RCRA, including properly treated toxic waste that is still considered hazardous, are intended for disposal in near-surface facilities regulated under Subtitle C of RCRA. EPA has developed detailed technical requirements on waste treatment and the siting, design, operation, and closure of disposal facilities. Thus, when viewed in relation to intended disposal technologies, there is basically only one class of hazardous chemical waste, regardless of the amounts of hazardous substances present i.e., a waste either is hazardous or it is not. 

Second, generic and site-specific assessments of near-surface disposal facilities for radioactive waste have shown that allowable doses to hypothetical inadvertent intruders usually are more restrictive in determining acceptable disposals than allowable doses to individuals beyond the boundary of the disposal site. This conclusion is based on predictions that concentrations of radionuclides in the environment (e.g., ground-water) at locations beyond the site boundary usually should be far less than the concentrations at the disposal site to which an inadvertent intruder could be exposed, owing to such factors as the limited solubility of some radionuclides, the partitioning of radionuclides between liquid and solid phases, and the dilution in transport of radionuclides in water or air beyond the site boundary. More people are likely to be exposed beyond the site boundary than on the disposal site, but acceptable disposals of radioactive waste in near-surface facilities have been based on assessments of dose to individuals, rather than populations. 

High-hazard waste Any nonexempt waste that generally requires disposal system more isolating than dedicated near-surface facility for hazardous wastes1 Concentrations of any hazardous substances that exceed limits for low-hazard waste... 

Low-Hazard Waste. Waste classified as low-hazard would be generally acceptable for disposal in a dedicated near-surface facility for hazardous wastes. Limits on concentrations of hazardous substances in low-hazard waste would be derived based on an assumption that the risk or dose to a hypothetical inadvertent intruder at a disposal site should not exceed acceptable (barely tolerable) levels. 

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