生產工程Production Engineering

Production(Fundamentals of Petroleum , UT-Austin , Chapter V)

生產工程 (Definition of production)

（ 1 ）將地層的流體（油或氣）由井底帶到地表。 ( bring the well fluid to surface)

（ 2 ）將地表的流體作處理（例如 : 油氣分離）， 以 作為輸送 到煉油廠之前的準備。 (preparing them for their trip through the pipeline to the refinery)

生產之階段（ Stages 或 phases ）（ 1 ）完井（ complete the well ） -- bring the fluid to the surface

The first step is to complete the well － that is , to perform whatever operations are necessary to start the well fluids flowing to the surface

（ 2 ）例行修護（ Routine maintenance operations ） -- doing whatever is necessary to keep the well producing

（ a ）修復磨損及故障的設備 -- replacing worn or malfunctioning equipment, are standard during the well's production lift

（ b ） Workover ( 修井 ) -- more extensive repairs, known as workovers, may be necessary to maintain the flow of oil and gas

（ 3 ）流體分離（ Separate the fluids) -- taking the fluids through a series of steps to purify, test, and measure them The fluid must be separated into its components , because well fluid are usually a mixture of oil , gas , and water. These must be treated , measure , and tested before they are run to the pipeline on their way to the refinery

Well completion 完井

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Well completion ( 完井 )

After a well has been drilled to the projected depth and the productive formation have been evaluated for their economic

worth and profit, work will begin to

（ 1 ） set casing ( 下套管 )

（ 2 ） prepare well for production ( 準備生產 )

（ 3 ） bring in the zone or zones ( 生產 )

Well Completion （完井方法的選擇依據）

Completion equipment and the methods employed are quite varied , and the decisions for an individual well are usually based on

－ the type of oil or gas accumulations involved ( 地層油氣的種類 ) － the requirements that may develop during the life of the well ( 生產歷程中可能需要的設備 ) － the economic circumstances at the time when the work is done ( 當時的經濟情境 )

Well Completion 不同狀況下之考慮 Low pressure, sometimes second hand pipe will be employed

if the oil accumulation has a marginal payout, and other expenditures ( 花費 ) will be scaled down ( 按比例縮減 ) accordingly .

If high pressure is anticipated and well life is expected to be long, however, the best grade of pipe with backup precautions ( 備份預防措施 ) will be needed .

The well

Typically, an oil or gas well will require

three concentric strings of large pipe :

－ conductor pipe 導管

－ surface casing 表層套管

－ oil string (production casing)

油層套管 / 生產套管

－ tubing 油管

（ 1 ） Conductor pipe 導管

- The conductor pipe prevents

the hole from caving in at the

surface are endangering ( 危及 ) the drilling rig foundation .

- It is usually cemented ,

but occasionally it is driven

into place by a pile ( 樁 ) driver.

（ 2 ） Surface casing 表層套管 - When the surface casing is set and cemented in place , it provides protection for freshwater formations.

- It also prevents loose shale and sand or gravel from falling into the hole and affords a means for controlling the flow of fluid from the well .

- Setting depths may vary from 500 ft to 5000 ft .

（ 3 ） Oil string油層套管 / 生產套管

－ The final casing for most wells is

the oil string, or long string.

－ The producing formation is usually

completely cased off, but sometimes

the oil string is set near just or on top

of the potential pay zone.

(4) Tubing 油管 － The final string of pipe usually run in a producing well is the

tubing .

－ Tubing is nearly always freely suspended in the well from the casinghead.

－ Advantage of putting a tubing ( 使用油管的優點 )（ a ） It's small diameter produces more efficient results than casing in a flowing well.（ b ） Tubing also makes a safer well completion possible .（ c ） Tubing is comparatively easy to remove when it becomes plugged or damaged .（ d ） Tubing , in conjunction with a packer , keeps well fluids away from the casing because the packer seals the space between the tubing and casing.

Casing, tubing, and packer arrangement in a flowing well

Wellhead井頭

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The Wellhead

The wellhead is made

up of a combination

of parts called

--- Casinghead

--- Tubinghead

--- Christmas tree

-- Stuffing box,

-- Pressure gauges

The Wellhead─The wellhead is the equipment used to maintain surface control

of the well.

─It forms a seal to prevent well fluids from blowing or leaking at the surface.

─The conditions expected to be encountered in the individual well determine the type of wellhead that is needed.

─Sometimes, all that is required is a simple assembly to support the weight of the tubing in the well.

─In other cases, the control of formation pressures is necessary, and a high-pressure wellhead is required.

The wellhead ( 井頭的功能 )

Surface control

Prevent well fluid from blowing or leaking

Support the weight of the tubing

Control of formation pressure

（ 1 ） Casinghead

─The casinghead is a heavy steel fitting at the surface to which the casing is attached.

─It provides a housing for the equipment from which intermediate strings of casing are suspended.

─During drilling and workover operations, the casinghead is used as an anchor for the pressure-control equipment that may be necessary.

（ 2 ） Tubing head

─ Similar in design and use to the casinghead,

the tubing head supports the tubing string,

seals off pressures between the casing and

the inside of tubing, and provides connections at the

surface with which the flowing liquid or gas can be controlled.

─ The tubing head is supported by the casinghead if a casinghead is used on the well.

（ 3 ） Christmas tree

─The control valves, pressure gauges, and chokes assembled at

the top of a well to control the flow of oil and gas after well has been drilled and completed are known as the Christmas tree, so named because of its shape and the large number of fittings branching out above the wellhead (fig.5.4)

─The pressure gauges reveal casing and tubing pressures. By knowing these pressures under various operating

conditions, better well control is possible.

Christmas tree

Completion methods完井方法

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Completion methods

A well-servicing contractor may move in a smaller rig to perform the operations necessary to put the well in production.

─The type of completion method used is determined by the characteristics of the reservoir and it economic potential.

─Among the various types of completion methods used are open-hole and liner completions （裸孔完井及襯管完井） perforating (perforated casing completion 套管穿孔完井 ) swabbing （抽吸法，早期的完井生產方法）

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Open-hole and liner completions裸孔完井及襯管完井

─In an open-hole, or barefoot completion, no production casing or liner is set opposite the production formation (fig 5.5).

Reservoir fluids flow unrestricted into the open wellbore. This type of completion method has limited use in certain

situations.

─In the liner completion, a screen liner is used to obtain communication between the reservoir and the wellbore.

Fig 5.5 Open-hole completion or barefoot completions

Well completions － completion methods

Casing Completions 套管完井

－ Conventional perforated casing completions － Multiple-zone completions － Water and gas – exclusion completions － Sand exclusion completion (gravel packing completion) 防砂

Perforating （ perforated casing completion 套管穿孔完

井）─Perforating is the process of piercing ( 穿透 ) the casing wall

and the cement to provide holes through which formation fluids may enter.

─Perforation should (a) provide a clean, undamaged, and productive perforation, (b) penetrate the producing interval as far as possible, (c) shoot a smooth and round entrance hole in the casing (d) produce minimal casing and cement damage, and (e) produce the maximum flow rate with the minimum number of perforations.

─ Two basic methods of piercing the casing wall are bullet perforating and jet perforating.

Bullet Perforating Bullet Perforator are lowered into the hole and fired

electrically from the surface. (fig 5.6) Bullets cause little casing damage and less damage to the

cement sheath between the pipe and wall of the hole than jet charges.

Jet perforating In jet perforating, shaped-charge explosives are employed

instead of bullets.

Perforating

Bullet perforation is more effective in formation of low to moderate compressive strength, while jet perforation is generally better in rock with high compressive strength.

A much safer well completion technique is to make the perforations after the tubing has been run and the packer set because the well is under absolute control at all times.

Thru-tubing perforation has been made possible by the development of perforating devices small enough to run through tubing.

Swabbing 抽吸法

Swabbing is a temporary operation that lower the fluid level in the well so that it can begin to produce

If enough fluid can be swabbed (lifted) out of the tubing so that the pressure in the formation is slightly greater than the hydrostatic pressure of the fluid in the tubing, the oil or gas will start flowing immediately after the perforation are made.

If the fluid does not flow after bring swabbed, a pump is installed as a permanent lifting device to bring the oil the surface.