Drives y Stimulation II Zu

7/28/2019 Drives y Stimulation II Zu

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DRIVES Y STIMULATIONSection AREADING COMPREHENSIONRead the following passage.The onlyvisible part of a flowing well is the Christmas tree, which isthe assembly ofvalvesand chokesat the production wellhead. The treecontrols the rate of flow to the surface and directs the oil into flow

lines. Viatheseflow lines, the oil is directedintostorage tanks orintogathering lines. Some Christmas trees have separate valves boltedtogether, some have all the valves let into one block ofsteel (calledsolid blocktrees), and others have a combination of the two.The forces that push reservoir fluids upwards to the tree are calleddrives. These natural production mechanisms are relative to the threesources ofpotentialenergyin the reservoir. As we have alreadyseen,thesesources of energy are the three pressurized reservoir fluids: gas,oil, and water. When the well hasbeenopened to the surface, thereisa pressure drop in the vicinityofthe well bore. This means, in the caseof solution-gas drive, thatwhich is dissolved in the oil begins to come

out of solution and to expand. As the gas does so, it displacesthesurrounding oil horizontallyinto the well. In the case of gas-cap drive,the expansion of the free gas displaces the oil downwardsinto the well.In water drive, the expansion of the aquifer watersweeps the oil out ofthe rockpores and upwards into the well.After a well has come on stream, the production ratemay not be highenough. A commoncause of this is low permeability of the reservoir.To raise the production rate, the well will have to be simulated. Thereare many ways of simulating a well, but the main ones are hydraulicfracturing and acidization.Hydraulic fracturing is a method of breaking open cracks and

fissures in the pay zone around the borehole. The fracturing fluid,usually a gel, is squeezedto the formation under a pressure which ishigh enough to break the formation down. When the pressure isreleased, however, the cracks must be kept open. For this reason,

propping agents are carried in the gel and are leftbehind to hold openthe cracks and fissures. The most common propping agents areroundedsandgrains, glassbeads, and walnutshells.Acidization can be used to stimulate reservoir rock which is soluble inacid. By dissolving the formation, the acid opens up and enlarges

ENTRADAS Y ESTIMULACI NSeccin ALECTURA DE COMPRENSINLeer el siguiente pasaje.La nicaparte visible de una circulacin de pozo es el rbol de Navidad, quees la reunin de vlvulasy obstruidoresen la produccin del pozo dirigido. Elrbol controla el porcentaje de circulacin a la superficie y dirige el aceite en

lneas de circulacin. Va estas lneas de circulacin, el aceite es dirigido entanques de almacenamiento o en lneas plegadas. Algunos rboles de Navidadtienen vlvulas separadas empernadas juntos, algunos tienen todas lasvlvulasdejadas en un bloque de acero (llamada "El bloque macizo o solido"rboles), y los otros tienen una combinacin de lo dos.Las fuerzasqueempujan los fluidos del reservorio hacia arriba en el rbol sonllamadas "Entradas". Estos mecanismos de produccin natural son relativos alas tres fuentes de energa potencialen el reservorio. Como ya hemos visto,estasfuentes de energa son los tres fluidos de reservorio presurizados: el gas,el aceite, y el agua. Cuando el pozo ha sidoabierto a la superficie, hay unsalto de presin en la proximidadde la perforacin del pozo.


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fissures in the rock around the borehole. In order to stimulatereservoirs consisting of limestone and dolomite, hydrochloric acid(HCl) is generally used. Hydrofluoric acid (HF) is used to stimulatecertainkinds ofsandstone reservoirs. It is also used to clean up porespaces which have been blocked by drilling-fluid clay.Special Words and ExpressionsVisible Capable of being seen.

Valves A valve is a device which stops. Starts, or regulates flow.Chokes A choke is a device which flow pressure.Via Along the path of; by way of.

Bolted togetherfastened together by means of bolts.Potential energy the energy that a body has because of its position or thearrangement of its parts.

In the vicinity of in the area or region of; near to.To expandto increase in volume. Metals expand when they are heated.The opposite of expand is contract.

Displaces takes the place of; pushes out of place.StimulatedTo stimulate something is to make its activity greater.

Hydraulic operated or effected by means of a liquid.Gela very heavy liquid suspension.

Is squeezed to is forced into; is compressed into.Propping agents materials which keep open, or prop up, cracks andfissures in reservoir rock.

Is solublein can be dissolved in.Acida water-soluble compound which can react with a base to form asalt containing hydrogen. Acids turn litmus paper red; bases turn litmus

paper blue.

Comprehension

a. By what route is oil directed into storage tanks?b. Define a solid-block tree.c. How can a liquid be tested to find out whether its an acid or a

base? (By)d. Name three substances that are water-soluble.e. If the drive mechanism in a reservoir comes from the water

zone, what in the water zone called? How does it operate?f. What is a combination tree made up of? (Some valves, and

others).


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g. As the gas does so (Section A) As the gas does what? h. What is the difference between hydraulic fracturing and

acidization?i. What are the two uses of hydrofluoric acid in well stimulation?

j. If propping agents arent used in the fracturing gel, what willhappen to the fissures in the vicinity of the borehole?

True or False?

Say whether the following are true or false. Correct the false ones.a. The chemical symbol for hydrochloric acid is H2SO4.b. Natural drive mechanisms depend on reservoir fluids.c. In a common garden hose, the device at the business end is a

valve.d. HCl is rarely used to stimulate dolomite reservoirs.e. Archimedes Principle states that the upward force on a body in

a liquid is equal to the weight of the liquid displaced.

Section BLISTENING COMPREHENSION I

1. Listen to the conversation between Fred, Dave and Steve.FRED: Right, then. Lets just go over the three diagrams again and besure were clear about what these different traps indicate.DAVE: In relation to drive, Fred?FRED: Yeah, but, um, tie them in a little with recovery, too.DAVE: Okay. Go ahead, Fred.FRED: Well take this one first. Steve?STEVE: Water drive. Good recovery, but the usual problems withentrained water.FRED: Right. And this one, Dave?

DAVE: Dissolved-gas drive. Fairly slow recovery.FRED: Thanks Dave. Now what about this third one. Steve?STEVE: Just a second. Its a bit difficult to see. Sure. Gas-cap drive.FRED: And recovery? Dave?DAVE: The free gas cap here is a large one, so recovery would probably

be very high.FRED: Good. Tomorrow we can have another look at-STEVE: -Christmas trees, Fred?FRED: Right again, Steve.


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DAVE: Subsea or surface?FRED: Both, Dave.

2. Now do this exercise based on the tape.a. What are the three men studying? What is Fred asking for? What

job do you think Fred does?b. Choose the right expression: Tie them in with recovery means (i)

Join them to recovery (ii) Relate them to recovery (iii) Point to

the diagrams about recovery.c. Which two types of trees does Dave.d. What expression is used instead of solution-gas drive?e. Why does Steve hesitate over the third diagram?

Section CSTRUCTURE PRACTICE

1. Adjectives from the PassiveExample: Sand grains which have been rounded are a common

propping agent.

Roundedsand grains are a common propping agent.Do the following in the same waya. Barite which has been ground is commonly used to weight

drilling muds.b. Pore spaces that are blocked can be cleaned up by acidization.c. Gas which is dissolved in reservoir crude can be an important

production mechanism.d. Items of equipment that have been lost in the hole must be

fished out.e. Reservoirs which are fractured have the highest permeabilities.2. Nouns from VerbsStimulatestimulationRecoverrecoveryDisplacedisplacement

Now put the verbs in brackets into their noun forms.a. (Produce) rates can be increased by (stimulate).

b. Gases can be converted to liquids by (pressurize).c. The (expand) of free gas displaces the oil downwards.d. Some trees are a (combine) of valves bolted together and ones


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into a solid block of steel.e. (Acidize) is used to enlarge the fissures in the rock around the

borehole.f. The diagram shows the (distribute) of water and hydrocarbons in

a typical trap.g. The (magnify) of the sample in this picture is x20.h. Viscosity describes the (resist) of a fluid to flow.i. On page 39 there is a (describe) of hydraulic fracturing.j. Hydrocarbon (accumulate) are found only in porous or fractured

(from).

3. Phrasal VerbsStand backBlow aboutMake up of

Stands are blew stood backon the rig back in August. (Unit 6)The string is made up ofa number of singles. (Unit 1)Choose from these phrasal verbs to complete the sentences below: latch

on to, go over, find out, wear out, clean up, run back in.a. The bottom-hole assembly can be used . The well.b. The bit so it was changed.c. After they had changed the bit, they again d. Quick, those collars!e. If you want what goes where, ask the superintendent. f. Lets just the three diagrams once more.

Drives y Stimulation II Zu

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