石油工程专业英语-采油技术基础productiontechnology

石油工程专业英语-采油技术基础productiontechnology内容摘要：

is further secured by a series of set screws. An adapter (also called a tubing “bon”) provides a transition from the tubing head to the arrangement of valves and fittings above the casing and tubing head, used to control flow (the “Christmas tree”). In the Christmas tree, the bottom valve, often called the master valve, is the primary means for pletely shutting in the well. This and other valves used in the tree are normally gate valves that operate by moving a metal barrier to block the flow stream. Often, safety Casing hanger Casing spool Hanger Casing head Tubing hanger adapter Tubing hanger Tubing head Casinghead and casing hanger installation and tubing head and tubing hanger installation. Courtesy’s Exxon. PART II Petroleum Technology 62 regulations require that one valve be pressureactuated to automatically shut off flow in case of operating problem or natural disasters. Offshore wells usually require a downhole safety valve in addition to this surface safety system. The tree allows for vertical entry into the tubing by removal of the top adapter. A “tee’’type fitting allows for redirection of the vertical flow stream to a horizontal flow line. The produced fluids in the flowing well, before entering the surface flowline, must pass through the smallest restriction in the surface flow equipment— the choke. Chokes, located in the Christmas tree, provide a means for controlling production rate by restricting the area available for flow. This restriction is normally a bean or orifice of a specified diameter, and must be inserted into the choke body. We may wish to maintain a certain flow rate for many reasons:  to prevent sand production。  to control water or gas production  to maintain the most efficient production rate for a particular reservoir producing mechanism。 or  to produce the well at a fixed allowable production rate designated by a governmental regulatory agency. In the case of a positive choke, the flow is controlled by alternately inserting various beans with appropriately sized orifices. With an adjustable choke we may vary the flow restriction mechanically without changing the bean. Tubing pressure is measured upstream from the choke (toward the well). Figure , show examples of surface flow control equipment for a variety of pletions. While most manufacturers make ponents with bolted flange connections, some panies also manufacture wellhead and Christmas tree equipment with clamp connections to allow speedy assembly. Wellhead and Christmas tree ponents are available for all types of specific design situations. Most equipment can be adapted to allow that different manufacturers’ ponents be bined in a single installation. As section has shown, the downhole and wellhead ponents of a pleted well can vary, depending on the plexity of the pletion design. Generally, the most important pletion ponents are the tubing string and the surface choke, because these ponents usually have the greatest effect on the flowing performance of a well. We have also seen that in some cases, the original pletion should be designed in anticipation of future or immediate artificial lift needs. This is an important point that needs to be kept in mind. The next section continues the description of the equipment that exists further downstream in the production system. PART II Petroleum Technology 63 Wellhead and Christmas tree for a dual tubing pletion utilizing clamptype connection. From Gray Tool Company Surface flow control equipment for lowpressure pumping well installation. PART II Petroleum Technology 64 Surface Production Facilities The fluid produced from a well is usually a mixture of oil, gas, water, and sediment at elevated temperatures and pressures. The oil alone is a plex mixture of many hydrocarbon pounds, and oils from different reservoirs have different physical and chemical characteristics. All crude oils have a certain amount of gas dissolved in them. A gas phase may exist in the production stream, having e out of solution with the drop in pressure up the tubing, or it may exist in and be produced from the reservoir as free gas. In some cases, the only hydrocarbons found in a reservoir exist as a gas and, thus, we have a dry gas reservoir. Formation water may be carried in the gas state as vapor, emulsified as a liquid with the oil, or produced as free water. Sand, silt, and clay from the formation can be carried by the produced fluids into the wellbore and be produced along with scale and corrosion products from the casing or tubing. Various contaminants can be present in the oil, gas, and water. These include CO2 , H2S, and dissolved salts. Surface production facilities are designed to turn this mixture into separate streams of clean, dehydrated oil and gas and safely disposable water. Only then can the oil and gas be metered and sold, or sent for further processing to a plant or refinery. Of course, the diversity of well fluid mixtures has led to the development of an assortment of vessels to clean and separate these mixtures at various pressures and temperatures. Let’s follow the production stream for an oil well, describing the equipment and its function at each step. Later section will do the same for a gas well. Separation The produced fluids leave the Christmas tree via a flow Line— usually a 2 or 3in (5 to 8cm) pipe, which may be below or above ground at onshore installations, or perhaps on the seafloor for a subsea pletion. Subsea pletions are often equipped with TFL or throughflowline connections whereby the flow line connects to the Christmas tree in a smooth loop. This arrangement allows for pr。