Petroleum Sience in English,Instructor: Guo Qing,1,行业材料,Chapter Six Petroleum Production Production may be considered as that section of the oil industry concerned with conveying（传送） hydrocarbons（烃） from the reservoir（油藏） to surface, and the separation（分离） of oil, gas, water, and solids to the extent necessary to provide a saleable primary product（初级产品） such as crude oil, NGL(natural gas liquids), and gas.,2,行业材料,Producing oil is an intricate（复杂的） art. Oil can be pumped out of the sponge rock（海绵状岩体） at a certain maximum（最大的） rate, determined by the viscosity（粘稠度） of the oil and the quality（质量） of the reservoir. Oil production must be managed carefully to avoid clogging（堵塞） or collapsing（跨塌） the pores（孔隙）, which can prevent a well from accessing（获取） much of the reservoir. Pumping too fast, pumping too slowly or interrupting（间歇式的）production can all damage an oilfield. And not only one but many wells must be drilled to fully exploit（开发） the reservoir, raising the expense（费用） of production.,3,行业材料,Drilling curved（斜的） and horizontal（水平的） wells into reservoirs is a common technique to increase production. Another technique involves fracturing（压裂） the reservoir rock by pumping fluids and sand into it under high pressure. The fluids open cracks（裂隙）, and the sand keeps them open to let out the petroleum. This can overcome low permeability（渗透率）. Treating the wellbore（井筒） with various acids（酸） or solvents（溶剂） can also raise permeability. This technique is called acidizing（酸化） .,4,行业材料,One of the most commonly uses methods of fracturing is hydraulic fracturing（水力压裂）. Hydraulic fracturing may be defined as the process of creating a facture（裂缝） or fracture system（裂缝系统） in a porous medium（孔隙介质） by injecting a fluid under pressure through a well bore in order to overcome native stresses（天然压力）and to cause material failure（岩石破裂） of the porous medium（孔隙介质）. Briefly it is the creation（形成） and preservation（保持） of a fracture in a reservoir rock（储集岩）. To fracture a reservoir rock, energy must be generated by injecting a fluid down a well and into the formation（地层）.,5,行业材料,Reservoir Production Mechanisms（机理） The production mechanisms which owe their existence to these sources of energy are referred to as “water drive”（水驱）, “solution gas drive” (or “depletion drive”)（溶解气驱）, and “gas cap drive”（气顶驱） respectively. The natural drainage of the oil through the reservoir rock under its own gravity（重力） provides a further production mechanism. A combination of drive mechanisms may operate in the same reservoir. Generally, however, one system will dominate（占支配地位） the others and the relative importance of these will change with time during the production of oil and for this reason it is convenient to consider each type of drive mechanism separately and care must be taken during the development of an oil field to use the reservoir drive pressures to their maximum extent（最大程度）.,6,行业材料,Water drive（水驱）: reservoirs drive their energy from water below the oil. Water sweeps the oil up and into the wells. Water drive (edge-water drive) is considered to be the most effective recovery mechanism of all. In order to enable this mechanism to function at its maximum effectiveness（最大程度上发挥作用）, it may be necessary to limit（控制） the rate of oil production so that the aquifer water（淡水） can enter the vacated（腾出空隙的） section of the oil-bearing zone as fast as the oil is withdrawn.,7,行业材料,If the oil production rate exceeds（超过） this limit there will be a decline（下降） in the reservoir pressure and a consequent reduction（相应地降低） in the energy available to produce the oil.,8,行业材料,Solution gas drive（溶解气驱） (dissolved gas drive or depletion drive) is caused by gas dissolved in the oil. In the subsurface（地下）, the oil is under high pressure. The higher the pressure, the more gas that can be dissolved in the oil. When a well is drilled into the oil reservoir, pressure is relieved（缓解） and gas bubbles（气泡） form in the oil.,9,行业材料,Expanding gas bubbles（气泡膨胀） force the oil into the well. Dissolved gas drive is very inefficient, producing only from 10% to 30% of the oil in place（地质储量）, leaving the rest in the reservoir.,10,行业材料,Gas cap drive（气顶驱） (free gas drive) derives（获取） its energy from the pressure of the gas in the free gas cap. The expanding free gas cap sweeps（扫） the oil into the well. Gas cap drive is relatively efficient, producing 355 to 50% of the oil in place.,11,行业材料,This type of reservoir is best developed with wells producing only from the oil portion of the reservoir, leaving the gas in the free gas cap to supply the energy.,12,行业材料,gravity（重力） is also a drive mechanism. It is present in all reservoirs, as the weight of the oil column creates pressure causing oil to flow into the well. This is usually insignificant（不太重要）compared to original pressures（原始压力） created by the other drive mechanisms. In the later stages（阶段） of oil production in a dissolved gas drive reservoir, however, gravity drainage（重力驱） becomes significant（重要）. This is called a gravity drainage pool（重