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1、Lesson 3 Production Technology,3.1 Completion Components,3.2 Surface production Facilities,3.3 Field Examples of Production Systems,3.4 System Performance,3.0 Introduction,3.0 Introduction,Now lets consider the well as part of a dynamic production system.Wells are drilled and logged,maps are revised
2、,and the reservoir begins to take shape as a volume having certain dimensions.(Big ones,hopefully!)But once production begins,the reservoir is only a part of a larger system that includes the reservoir,wellbore,tubing string,artificial lift equipment,surface control devices,gathering lines,separator
3、s,treaters,tanks,and metering devices.,计量装置,All of these elements behave according to their own specific performance relationships,but each,in turn,also depends upon and influences the other elements.Production engineers are concerned with the interaction of these performance relationships as produc
4、tion occurs over time,anticipating performance changes and designing the system to maximize recovery of oil and gas economically.,3.0 Introduction,This chapter outlines production system equipment,starting with the completed well and moving along the flow path through the surface facilities.The same
5、 path is then retraced,but this time focusing on the dynamic flowing performance relationships that govern fluid movement through the system.,地面设备,3.0 Introduction,3.1 Completion Components,Together with the cement sheath holding it in place,the casing performs several important function:,supporting
6、 the sides of the hole;preventing communication of fluids and pressures between shallow and deep formations;allowing for control of pressures;providing a base for surface and subsurface equipment.,水泥环,A cross section of a typical casing installation is shown in figure 3.1.The number of concentric“st
7、rings”,their relative sizes and strengths,the setting depths,and cementing techniques will vary according to the depth and drilling program for the well.The conductor prevents the surface hole from caving and it also prevents lost circulation.In offshore situations,the drive pipe is hammered into th
8、e mud to provide a conduit from below the seafloor to the production deck,and the conductor casing is set inside the drive pipe.,击入式管子,循环漏失,3.1 Completion Components,Surface casing provides protection for shallow freshwater formations,and the producing string of casing is set to or through the produ
9、ctive zones,to isolate them and allow for selective completions.There may be intermediate casing strings between surface and production casing if the depth of the well requires it.Each casing string is cemented in place and the production string is perforated across the productive zone.,淡水层,生产层,技术套管
10、,表层和生层套管,3.1 Completion Components,The central downhole component of a completed well is the production tubing.There are four primary reasons for utilizing production tubing as a conduit for producing fluids:,It is relatively easy to remove if problems develop.,It isolates producing fluids from the
11、casing and makes control of the fluids easier.,It facilitates circulation of heavy fluids into the wellbore to control the well.,Its smaller diameter allows for safety devices and artificial lift equipment to be included in the completion design.,It allows for more efficient producing rates from low
12、er productivity wells.,生产油管,Tubing is suspended from a tubing hanger within the wellhead at the surface,and the producing zone(s)may be isolated by production packers in the tubing string.A well may be completed with several strings of tubing(dual completion,triple completion,etc.),each carrying pro
13、duction from a different zone.Some extremely productive wells produce through casing without tubing,or through both tubing and the casing-tubing annulus.,3.1.1 Tubing Components,The design of a particular completion depends on:,the number and type of productive zones;the expected pressures and flow
14、rates;the need to control sand production;the need for artificial lift or stimulation;and the regulations governing operations in the area.,Figure 3.3 shows schematic examples of a number of typical completions.In addition,the following definitions and associated figures describe the most common com
15、ponents of those completion examples.,Packer:The packer seals the casing-tubing annulus with a rubber packing element,thus preventing flow and pressure communication between tubing and annulus.Packers are designed either to remain in the well permanently or to be retrieved if future downhole work is
16、 required.,封隔器,3.1.1 Tubing Components,Multistring Packer:The multistring packer seals the casing-tubing annulus where more than one tubing string is involved.Up to five-string packers are available,but more than a triple completion is rare because of the difficulty of retrieval if problems develop.
17、,Sliding Sleeve:the sliding sleeve component is a wireline-operated sleeve,which will open or close ports in the tubing to allow fluid in or out.,滑套,多管柱封隔器,Tubing Anchor:The tubing anchor is essentially a packer without the sealing element and is designed to prevent tubing but not fluid movement.,油管
18、锚,Blast Joint:A blast joint is a section of heavy-duty tubing located opposite production perforations in a multistring completion.,耐磨接头,Safety Joint:The safety joint allows for the parting of an auxiliary tubing string beneath a multiple string packer when the packer is being retrieved.,安全接头,Landin
19、g Nipple(fig.3.11):Landing nipples are a variety of short tubing components with interior profiles that allow for the wireline setting of plugs,safety valves,chokes,pressure gauges,etc.,within the tubing by using the appropriate locking device.,座放短节,Figure3.11 Landing nipple and flow coupling instal
20、lation.Courtesy Baker Packers,a Baker Oil Tools Company.,Subsurface Safety Valve:This component is a valve assembly within the tubing string,which is designed to close in case of emergency.,井下安全阀,Figure3.13 Tubing retrievable subsurface safety valve operation:(a)closed,(b)open.Courtesy Baker Packers
21、,a Baker Oil Tools Company.,3.1.2 Surface Flow Control Equipment,The valves and connections at the top of the well are often referred to collectively as the“wellhead”or“Christmas tree”.,The design of the entire arrangement depends on several factors:,the expected maximum and operating pressures;the
22、number and sizes of casing strings;the number and sizes of tubing strings;,采油树,the need for auxiliary equipment,such as subsurface safety valves,electrical conduits for submersible pumps,and chemical injection equipment;,the outside environment.onshore,offshore,or subsea;,the inside environment:CO2
23、and H2S content of produced fluids or corrosive formation water;,辅助设备,Figure 3.14 shows a typical surface flow control installation for a multiple casing string,single tubing string,flowing well.,Figure3.14 Surface flow control installation for a single tubing string,mulyiple casing string,flowing w
24、ell.Courtesyrs Exxon.,自流井,The casinghead(fig.3.15)is screwed,or welder to the outermost casing stub.,套管头,The tubing head performs a function similar to the casinghead,in that it accommodates a tubing hanger,which usually screws onto the top of the tubing string(s)and seals off the casing-tubing annu
25、lus with metal-to-metal and/or rubber sealing elements.Often the tubing hanger is further secured by a series of set screws.An adapter(also called a tubing“bonnet”)provides a transition from the tubing head to the arrangement of valves and fittings above the casing and tubing head,used to control fl
26、ow(the“Christmas tree”).,In the Christmas tree,the bottom valve,often called the master valve,is the primary means for completely 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,The produced fluids i
27、n the flowing well,before entering the surface flow-line,must pass through the smallest restriction in the surface flow equipmentthe choke.,底阀,油嘴,We may wish to maintain a certain flow rate for many reasons:,to prevent sand production;to control water or gas productionto maintain the most efficient
28、production rate for a particular reservoir producing mechanism;orto produce the well at a fixed allowable.a 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.
29、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 3.20,3.21 show examples of surface flow control equiprnent for a variety of completions.,Figure3.20 Wellhead and Christmas tre
30、e for a dual tubing completion utilizing clamp-type connection.From Gray Tool Company,Figure3.21 Surface flow control equipment for low-pressure pumping well installation.,As section 3.1 has shown,the downhole and wellhead components of a completed well can vary,depending on the complexity of the co
31、mpletion design.Generally,the most important completion components are the tubing string and the surface choke,because these components usually have the greatest effect on the flowing performance of a well.We have also seen that in some cases,the original completion should be designed in anticipatio
32、n of future or immediate artificial lift needs.This is an important point that needs to be kept in mind.,3.2 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 complex mixture of ma
33、ny hydrocarbon compounds,and oils from different reservoirs have different physical and chemical characteristics.,Formation water may be carried in the gas state as vapor,emulsified as a liquid with the oil,or produced as free water.,地层水,Surface production facilities are designed to turn this mixtur
34、e 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 a
35、nd separate these mixtures at various pressures and temperatures.Lets follow the production stream for an oil well,describing the equipment and its function at each step.,3.2.1 Separation,The produced fluids leave the Christmas tree via a flow Lineusually a 2-or 3-in(5-to 8-cm)pipe,which may be belo
36、w or above ground at onshore installations,or perhaps on the seafloor for a subsea completion.Subsea completions are often equipped with TFL or through-flow-line connections whereby the flow line connects to the Christmas tree in a smooth loop.This arrangement allows for production devices(plugs,etc
37、.)to actually be pumped through the flow line and into the tubing,thus eliminating the need to disconnect any Christmas tree fittings.,Separators are usually classified by physical shape,and figure 3.22 shows the basic vertical,horizontal,and spherical separator configurations.A conventional separat
38、or divides the produced fluid stream into oil and gas,or liquid and gas,and is known as a gas-oil separator or gas-liquid separator.Sometimes separators are also called“traps.”,Figure3.22 Separator configurations,气液分离器,Metering separators accumulate the separated oil,or oil and water,isolate the liq
39、uid phases in calibrated chambers,and periodically discharge the measured volumes into separate outlets.Such separators can be designed to meter only the oil,or both oil and water.Special designs are also available for very viscous oil,or oil that tends to“foam.”,计量分离器,Lets discuss the operation of
40、a typical vertical,two-phase,gas-liquid separator,shown schematically in figure 3.23.The oil-gas-water mixture enters through an inlet on the side of the tank-shaped vessel.,Figure3.23 Conventional vertical separator.Courtesy Sivalls,Inc.,The gas phase,which is directed to the upper portion of the v
41、essel,is usually passed through a mist extractor to remove minute liquid droplets entrained in the gas.Here,three processes act to separate liquid from the gas:flow velocity changes;direction changes;and impingement,or the adherence and coalescence of liquid mist on a surface.A combination of these
42、three processes is incorporated into a coalescing pack-type mist extractor made of knitted wire mesh or layers of inert particles with shapes designed for maximum surface area.,Centrifugal-type mist extractors(fig.3.26)used in vertical separators have a set of vanes that cause the circular motion of
43、 gas,throwing the heavier liquid droplets to the wall of the vessel to drain to the bottom.Its efficiency increases as the velocity of the gas stream increases.,Figure3.26,Vertical separators are often used on low to intermediate gas-liquid ratio well streams.They are more readily cleaned if sand or
44、 paraffin are produced,and occupy less floor space on offshore platforms.However,a vertical separator can be more expensive than a horizontal separator with the same separation capacity.Horizontal separators,therefore,are usually more cost-efficient,especially for high to medium gas-liquid ratio str
45、eams,for liquid-liquid separation,and in applications where foaming oil is a problem.,Horizontal separators often have closely spaced horizontal baffle plates that extract liquids.A double barrel horizontal separator has a higher liquid capacity because incoming free liquid is immediately drained aw
46、ay from the upper section into the lower.This allows a higher velocity gas flow through the upper baffled section.Spherical separators are much less common than vertical orhorizontal types.They tend to have lower installation and maintenance costs.They are more compact,but lack the capacity for high
47、 gas rates or liquid surges.,Separators are sized according to the expected oil and gas production rates,the necessary operating pressure and temperature,and the oil and gas properties.,It is important to remember that the physical and chemical characteristics of the crude oil and gas entering the s
48、eparator help determine the degree of separation possible at a given operating temperature and pressure.Separating the gas held as bubbles in the oil,or oil entrained as droplets in the gas,can be accomplished by manipulating the fluid stream.,3.2.2 Oil Treatment,In many oil fields,following the ini
49、tial gas-oil separation process,the oil must be treated to remove water,salt,or H2S.Most pipeline quality oil must have its water content reduced to the 0.2 to 2 by volume range.Because salt water is generally associated with oil in the reservoir,its production along with the oil is not unusual.Almo
50、st all well streams contain water droplets of various sizes.,水滴,The water cut measured on one or several samples of the well stream normally refers to free water,and is expressed as the volume of water relative to the total volume of liquid.,The sample is assumed to be representative.A free-water kn
