Shadowing Practice: Basic Introduction To Oil & Gas Well Perforating - Learn English Speaking with Video
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333 משפטים
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1
In the preceding video library module, we talked about cements and cementing practices.
2
A continuous competent sheath of cement around the casing is very important to the safe, efficient production of oil and gas from our well.
3
Now comes the next important step, selectively opening those zones we wish to produce by perforating the casing,
4
cement, and the formation.
5
Perforating is not just a matter of punching holes in the casing.
6
If our well is to achieve its potential, those holes must be deep enough to reach past any formation damage caused by the drilling and cementing process.
7
They must also be of sufficient number and arrangement to allow the formation fluids to flow into the wellbore unhindered.
8
They must be unobstructed by mud or debris,
9
and finally, they must be in the right position opposite the zones we have identified as productive prior to setting our casing.
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Accomplishing these objectives in a safe and cost-effective manner is the goal of any perforating program.
11
Poor perforating practices can easily make a 200-barrel of oil per day well
12
out of a discovery with perhaps 2,000 barrels of oil per day potential.
13
Good perforating practices can help us maximize the value of the hydrocarbons we've found.
14
In this module, we shall first outline the basic perforating options available to the engineer.
15
We shall find out that achieving the objectives just mentioned may require a few compromises, with the exception of safety, which should never be compromised.
16
We shall also take a look at the work that has been done to relate perforator performance to well productivity, the final measure of our success.
17
And we shall follow the progress of a perforating job, taking a close look at each important procedure.
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First, let's look at just what perforating options exist.
19
Cased holes may be perforated in several ways.
20
using conventional casing guns run into the well on electric wireline through wireline pressure control equipment,
21
using through-tubing guns run into the well after the tubing has been installed,
22
or using tubing-conveyed perforating guns run on the bottom of the tubing string and detonated using mechanical,
23
electrical, or pressure-activated firing mechanisms.
24
With each of these delivery methods, there is an option of perforating.
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Overbalanced, with a higher pressure in the wellbore than in the formation, or underbalanced, with a wellbore pressure lower than formation pore pressure.
26
Also, the delivery system for placing the shaped charges at the
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proper location via wireline may be categorized as one of three possible types.
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Retrievable, consisting of a cylindrical hollow steel charge carrier, which is retrieved after firing and may then be discarded, as in the case of scallop guns,
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or reused several times, as in the case of port plug guns.
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Semi-expendable, in which case the perforating charges are conveyed into the well on a retrievable metal or wire carrier.
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or fully expendable, where the charges and carrier linkage disintegrate on detonation and only the wireline is retrieved.
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Generally speaking, the larger diameter casing guns run via wireline will carry larger charges
33
and thus give larger perforation diameters and greater penetration depths than the smaller through-tubing guns.
34
Through tubing perforating, however, is a more practical method for underbalanced perforating than using conventional casing guns.
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And underbalanced perforating can help maximize productivity.
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Tubing conveyed perforating seems to provide a means to combine both the larger high-performance guns with the flexible pressure conditions.
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So we see that in considering just these perforating features, wire line versus tubing conveyed, over balanced or under balanced,
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retrievable or expendable guns, we already can come up with at least a dozen different useful design combinations to choose from.
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All this is without yet considering the variety of shape charges available.
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Let's look at how a shape charge functions.
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The shaped charge
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or jet perforator first came into use in the oil field
43
in the 1950s following the development of explosive technology during the Second World War.
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The four important components of the shaped charge are the conical metallic liner, the main explosive charge, the primer explosive,
45
and the case that encloses the charge.
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simply stated the firing is electrically initiated by the detonator
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or blasting cap via the detonating cord
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which in turn sets off the main charge explosive pressure on
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the metal liner causes it to collapse inwardly along its axis forming a high velocity jet of fluidized metal
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moving at a velocity of 25,000 feet per second and with a pressure of 15 million pounds per square inch, the jet displaces the casing,
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cement, and formation, creating a perforation in only several hundred microseconds.
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Depending on the design of the shaped charge and the type of materials being perforated, the perforation length is generally about 2 to 20 inches,
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5 to 50 centimeters, and the entrance hole diameter about 0.2 to 1 inch, or 0.5 to 2.5 centimeters.
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There is a zone of crushed rock around the perforation
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and the precise shape of the perforation will vary somewhat depending on charge geometry, gun positioning, and target characteristics.
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For example, although the exterior of these charges look identical,
57
this charge is designed to give large diameter perforations for easy gravel packing,
58
while this charge is designed to penetrate deeply with a somewhat smaller entrance hole.
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Here we see a charge that is designed to be run in a six inch
60
or seven and a quarter inch diameter carrier, while this charge is made for a one and eleven sixteenths inch carrier.
61
There is quite a bit less explosive power in this smaller charge,
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but that power can still be focused on maximizing hole size or penetration depending on the needs of the completion.
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The position of the gun in the casing is another important parameter in determining the size of the perforation.
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Gun clearance is the distance from the casing inner surface to the gun.
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Penetration and hole size generally decrease as clearance increases.
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This issue is particularly important when small diameter guns are run through tubing into larger diameter casing.
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In such situations, the gun needs to be positioned against the side of the casing to create a single line of deep perforations.
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This arrangement, called zero-degree phasing, may introduce an undesirable pressure drop in high-rate wells.
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Phasing the charges at 60, 90, 120, or 180 degrees would reduce this problem,
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but at the price of reduced penetration and hole diameter when using through-tubing guns.
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The third most important factor in shaped charge performance is the strength of the target material.
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For example, a charge
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that penetrates 5 inches into the Berea sandstone target shown here will only penetrate 2 inches in a much stronger sandstone.
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In deep reservoirs where the formation effective stress is great, the penetration depth may be much less than surface tests indicate,
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and this factor must be considered when choosing a perforator.
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Charge performance is also affected by the quality control applied during its manufacture, where precise control of the liner and charge dimensions is critical.
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The care with which the charges are stored and transported is also quite important.
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Charges should be stored in sealed boxes until ready for use.
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Correct alignment of the shape charges within the charge carrier, whether it be a semi-expendable strip carrier, a port plug gun, or any of several types of scallop guns,
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is a very important final step in the gun assembly process.
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The added cost of quality control in manufacture and assembly is a wise completion investment.
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We mentioned the three categories of wireline perforation systems, steel hollow carrier guns, semi-expendable guns, and fully expendable guns.
83
Let's take a look at some of the advantages and disadvantages of each option.
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In the case of retrievable hollow carrier guns, the charges are positioned and sealed within a steel cylinder, surrounded by air at surface pressure.
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Each charge is aligned with a threaded port plug in reusable guns, or behind a thinner portion of the carrier wall in scallop guns.
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Semi-expendable guns typically consist of a series of individually sealed charge cases designed to disintegrate after firing,
87
leaving only the carrier strip or wires to be retrieved.
88
In the case of fully expendable guns, only the wire line remains to be retrieved.
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The advantages of retrievable hollow carrier guns include high reliability because all components are protected within the carrier,
90
heavier and stronger construction than expendables, permitting rougher treatment and faster running speeds, generally higher temperature and pressure resistance,
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Very little debris left in the well.
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Retention of the explosive force within the carrier, eliminating casing deformation.
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A positive indication of firing provided by the condition of the port plug.
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On the other hand, even small diameter retrievable guns may have trouble running inside crooked tubing because of their rigidity.
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The carrier takes up more space and the charges may have to be smaller than comparably sized expendable guns.
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and the weight of the gun assembly may limit its length
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and thus the interval that can be perforated on a single run into the well.
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Considering expendable guns, we can say that they are generally cheaper and easier to assemble, are somewhat lighter and more flexible than hollow carrier guns,
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and size for size generally offer more penetration than comparable retrievable guns that can be run in the same size tubing.
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However, expendable guns can deform casing when detonated.
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leave substantial amounts of debris in the well, and are generally not as sturdy, leak-proof, and resistant to pressure and temperature as retrievable guns.
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The typical sizes and specifications of casing guns and through-tubing guns are detailed in your manual.
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In designing a perforating program and choosing a perforator, the engineer must consider the relative importance of hole size,
104
penetration, and shot density.
105
The size of the completion tubular components and the extremes of pressure and temperature are also important to the choice.
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For example, we may be convinced of the need for perforating underbalanced and through tubing in a given situation.
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If we suspect serious drilling damage, we may decide to use expendable charges for maximum penetration and accept the risk of gun breakage,
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extra debris, and possible casing damage.
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However, if the well is deep and hot, the durability of a hollow carrier may be important enough to
110
bargain some loss of penetration for a higher percentage of properly fired charges.
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Each situation requires careful consideration of the alternatives.
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Making such decisions requires that we be able to test commercially available charges and compare their performance,
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then extrapolate that performance to downhole conditions and its effect on actual well productivity.
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Currently, the industry relies on standard testing procedures developed by the API for evaluating well perforators.
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These procedures include a surface field test carried out in casing cemented within a concrete drum, and a laboratory test carried out using a Berea sandstone target
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placed inside a special core holder designed to permit flow through the perforation.
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These tests do not duplicate bottom hole well conditions precisely,
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so the data on perforation dimensions and cleanliness are not always useful in an absolute sense.
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However, if the tests are carried out correctly, the results can be used in a relative sense to compare commercially available charges.
120
Examples of the API test data recording forms are shown in your manual, along with a summary of the API tests themselves.
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But the true effectiveness of any perforator is measured in the well's productivity.
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Attempts to determine the relative importance of perforation parameters on well
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productivity have led to the development of mathematical models to simulate perforations.
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As these models become increasingly sophisticated, more is learned about perforation behavior.
125
Through this research, which is discussed in your manual,
126
we can now make some qualified generalizations about the relative importance of the four basic perforating parameters.
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shot density or number of shots per unit length, penetration, hole size, and phasing.
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For example, high shot density is considered of greatest importance in anisotropic or laminated reservoirs.
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Penetration is less important than shot density when drilling damage is minimal.
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However, in deep damage situations, it becomes critical.
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Some type of angular phasing is important when high rates are expected, but generally speaking, phasing should not be gained by sacrificing penetration.
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Hole size is relatively unimportant beyond a minimum of 0.25 inches unless the well must be gravel-packed or fractured,
133
in which cases hole size is very important.
134
We should emphasize that obtaining an adequate shot density not only requires
135
that the appropriate number of charges be run into the hole and that they fire correctly,
136
but that the resulting perforations remain unobstructed and open to flow.
137
The effective shot density depends on the type of formation, the quality of the charge, the type of completion fluid,
138
the magnitude and direction of differential pressure, and the flow time allowed for cleanup.
139
The type of formation will influence the depth of the perforation and the degree of rock crushing.
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The charge quality will influence the uniformity of the perforation tunnel and the type of debris that must be removed.
141
Most importantly, positive pressure perforating can result in plugged perforations.
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Even though subsequent swabbing may remove some plugging, other perfs will remain plugged once a few perforations are open.
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If clean, solids-free, formation-compatible fluids are used when perforating overbalanced, the degree of damage can be decreased.
144
However, reverse pressure or underbalanced perforating can greatly enhance perforation cleanup.
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Excess underbalance can also lead to problems.
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of the well, migration of fine plugging particles through the formation, or on rare occasions even casing collapse.
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Several researchers have suggested under-balance ranges for different permeability formations and different formation fluids,
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and these are given in section two of your manual.
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In any case, a volume of fluid should be flowed from the well after perforating to remove perforating debris
150
and improve the condition of the crushed zone should not be
151
injected into before they have been given a chance to clean up.
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There are several techniques for achieving a high effective shot density.
153
Under balanced through tubing wire line perforating, under balanced tubing conveyed perforating, positive pressure perforating with reverse surging,
154
and positive pressure perforating with perforation washing.
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In through tubing perforating the tubing and packer are run and set in the cased unperforated well.
156
Pressure control equipment is installed and tested.
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The gun assembly, including the charge carrier, weights, positioning tool, and collar locator,
158
are run into the tubing on a single conductor cable.
159
After firing, the well is typically flowed for 15 to 30 minutes before the gun and or cable is recovered.
160
It is important to design the degree of underbalance to prevent
161
blowing the cable up the hole due to frictional forces imposed by the flowing cushion fluid.
162
With tubing conveyed perforating, a hollow carrier gun is run into the well on the tubing string.
163
The tubing may be run dry or partially filled with a fluid cushion to establish the proper level of underbalance.
164
The packer is set and the vent is open to equalize the pressure below the packer with the tubing.
165
The gun is fired using mechanical, electrical, or pressure activation, and flow is immediately established through the vent.
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The gun may then be dropped into the rat hole for full bore flow.
167
Compared to through tubing perforating, we can say that tubing conveyed perforating,
168
one, allows greater penetration and multiple phasing because larger guns can be effectively centralized by virtue of their size.
169
Two, permits a greater degree of underbalance without risk of blowing the gun up whole.
170
And three, may be the least expensive option in cases where significant rig time is saved, although the equipment and service may cost more.
171
However, because the gun is usually not retrieved, we can never be positively certain of individual charge detonation, as with wireline conveyed guns.
172
Good charge quality control should reduce the risk of misfires in either case.
173
The two other types of perforation cleanup techniques listed in your
174
manual first require conventional perforation of the casing in an overbalanced condition using larger guns and clean, solids-free completion fluids.
175
Then, in the case of the perf surge technique, an underbalanced tubing string is run into the well and set with a packer.
176
When a shear disc within the tubing string is ruptured, the perforations are subjected to a sudden surge of drawdown,
177
expelling any debris that may be present due to the overbalanced perforating.
178
In the perf wash technique, the conventionally shot perforations are washed using a cup assembly
179
that forces clean fluid into one set of perforations and out of another.
180
Generally speaking, tubing-conveyed perforating is more consistent in obtaining clean perforations, followed by the perf surge and then the perf wash techniques.
181
In your manual is a discussion of the important points to be observed when perforating for gravel packing and for fracturing.
182
Gravel pack completions are typically shot with large hole diameters
183
and high shot densities to facilitate the placement of gravel-packed sand within the perforations
184
and to minimize producing fluid velocity through the perforations.
185
Perforating prior to fracturing is typically done with conventional casing guns and positive pressure.
186
Phasing of the perforations may increase the likelihood that the perforations will come close to aligning with the azimuth of formation fracture.
187
When several zones must be fractured, limited entry fracturing is sometimes employed.
188
In this technique, the perforation diameter
189
and number are limited in order to maintain a high bottom hole pressure and break down successive zones.
190
Penetration, shot density, phasing, and hole diameter are the variables that may be adjusted depending on the particular perforating situation.
191
Generally speaking, a technique
192
that ensures the maximum number of open perforations extending beyond any damage is the best alternative for a natural completion.
193
When fracturing or gravel packing is to be undertaken, perforation diameter becomes important.
194
In the next unit, we shall follow a perforating job as it is performed.
195
For now, please read sections 1 and 2 in your manual and work the appropriate exercises.
196
Most companies that offer perforating services also offer a variety of open hole and cased hole logging services.
197
And much of the basic equipment is the same.
198
The equipment includes the perforating tools themselves,
199
of course, the cable, the sheaves,
200
indicator, the logging truck, including a cable winch and electronic control panels,
201
and the pressure control system.
202
The tools include a casing collar locator run above the perforating guns
203
which magnetically detects the position of each casing collar as the tool string is pulled up the hole.
204
Gun weights are sometimes added to help move the tool string down the hole.
205
Remember that the well pressure is acting against the cross-sectional area of the cable. For example,
206
a common cable size of 7 32nd of an inch would
207
need a tool string weight of 190 pounds to exactly offset
208
the force exerted on the cable suspended in a well with 5000 PSIA at the surface.
209
The monoconductor cable normally used for perforating is an armored line with several layers of armor and with an insulated conductor core.
210
If multi-conductor cable is used, as is sometimes the case in low pressure situations,
211
the normal seven conductor electrical wire line cable is used with its armor layers and individually insulated conductors.
212
The sheave assembly is used to suspend the tools over the well and direct the cable from the truck or wireline unit.
213
Between the top sheave and the rig elevators or crane is a tension measuring device which measures the strain on the cable.
214
Modern perforating and logging trucks include the drum of conductor cable
215
and the winch system to spool it in and out of the well.
216
A depth measurement device for keeping track of the tool's position.
217
electrical control equipment and a 120 volt AC generator
218
and also a recording device for displaying the measured log data versus depth on a film strip
219
or for recording it on magnetic tape
220
the pressure control equipment is the most important component of the perforating system
221
because it allows the perforating guns to be lowered into the well or retrieved under pressure
222
The assembly consists of a blowout preventer, a riser pipe to contain the perforating tools,
223
a flow tube assembly, and an upper seal or stuffing box.
224
When closed, the blowout preventer seals tightly around the cable, preventing pressure from communicating around the cable with a riser.
225
The riser pipe consists of pipe sections with quick connect couplings.
226
These couplings are designed to let the internal riser pressure work to maintain the coupling seal.
227
The flow tube assembly provides the offsetting force, which prevents well fluid from flowing out of the riser.
228
When cable is moving into or out of the well under pressure, grease is continuously pumped into the small annular space between cable and flow tubes.
229
Because the space is so small, the force required to offset the well pressure can be easily applied.
230
At the top of the assembly is a hydraulically activated pack-off.
231
The hydraulic pressure compresses a rubber packing ring around the cable in an emergency to prevent cable movement
232
and seal off the assembly.
233
In normal perforating situations, the pressure control assembly is either bolted to the blowout preventer stack of a drilling rig
234
or bolted to the top flange of the tubing head or Christmas tree in through tubing perforating.
235
The equipment is pressure tested after it's installed.
236
After taking the necessary safety precautions to prevent stray currents from accidentally detonating the charges,
237
a voltmeter is used to check for voltage between wellhead and truck.
238
The casing, rig, and truck are grounded together,
239
and the unit power sources are turned off.
240
After the guns are assembled, a special procedure is followed by the service company engineer to
241
carefully arm the charges with the blasting cap used to detonate them.
242
The cap is held in a specially designed safety tube while the arming is accomplished.
243
Of course, the perforations must be correctly positioned in the well opposite the formations we wish to produce.
244
Generally, we have some type of open hole log, which indicates the productive formations and the depths at which they were found.
245
These depths are measured relative to the Kelly bushing of the drilling rig on location when the well was logged.
246
When we wish to perforate, the hole will have been cased and the rig may or may not be on location.
247
So how do we pick the correct point to perforate?
248
Normally, we first run a cased hole log, such as a gamma ray or neutron log, along with the casing collar locator.
249
This log, called the perforating depth control or PDC log, relates the depth of the formations behind pipe to the casing collars.
250
This log is then laid over the open hole reference log, which has the desired perforations clearly marked.
251
The radioactive trace is carefully matched and checked by shifting up and down to avoid correlating the wrong formations.
252
The marked perforation intervals are traced onto the PDC log.
253
Also, remember that the casing collar locator is several feet away from the radioactive tool.
254
This difference must be compensated for within the electronics of the system through a memorizing feature, or else by hand on the PDC log.
255
With the perforating depth control log in hand, we now have a relationship between the formations to be perforated,
256
the desired perforation intervals, and the casing collar depths.
257
Next, the gun assembly must be carefully measured and sketched, sketched, noting the distances from the casing collar locator to the top shots of each charge carrier
258
and the length of each gun.
259
The depths at which the casing collar will be located
260
when the charges are positioned correctly across the intervals to be perforated must be noted for each gun.
261
The gun assembly is introduced into the riser and the pressure control assembly is sealed.
262
A grease seal is established in the flow tube.
263
The blowout preventers or Christmas tree swab valve can now be opened
264
when the gun assembly is ready to be run into the well.
265
Now, in order for the guns to be positioned correctly across from the intervals we wish to perforate,
266
we need to correlate the casing collars measured by the gun assembly with those on the PDC log.
267
Here is where a few odd-sized casing joints, run in the vicinity of the productive zone, will be helpful in distinguishing one collar from another.
268
Starting below the perforating depth, the collars are logged up the hole, and the log is correlated with the PDC log.
269
Any necessary depth correction is made to the odometer.
270
The collars are logged again, and the match checked by shifting the log one collar length in either direction.
271
With a gun assembly on depth, the collar locator is positioned at the designated depth and the gun is fired.
272
If the well is perforated under-balanced through tubing, the placement of the pressure control assembly on top of the
273
tree allows the well to be flowed for a time before removing the gun and cable.
274
If a retrievable gun is used, the engineer should verify, after retrieving the gun, that all the charges have fired.
275
An inspection of the port plug holes, or scallops, will indicate if the charges have fired properly.
276
A round hole near the center of the port plug, or scallop, indicates that the charge was correctly aligned and properly functioning.
277
Any charge debris left in the carrier should be relatively small fragments.
278
Practically whole charge cases indicates low-order firing of the charge.
279
As with any completion operation, thorough job planning is a prerequisite to a successful perforating procedure.
280
And the first step in planning a perforating job is to accumulate the necessary data.
281
Of primary importance is information on the well tubulars, specifically casing or liner size and weight,
282
tubing size and weight, packer type and pressure limits,
283
wellhead connection, and pressure test specifications for tubing, casing, and wellhead.
284
Other conditions that must be specified or estimated include expected bottom hole temperature, formation pressure and bottom hole pressure desired,
285
formation and wellbore fluids, fluid levels in tubing or casing, surface pressures, pressure and rate limits for surface facilities,
286
and the need for H2S equipment, if any.
287
Of course, the open hole log used to pick the perforating intervals will be needed, with the intervals clearly marked and the depths recorded.
288
The order in which multiple intervals must be perforated is also important.
289
Your manual has some additional suggestions on choosing a perforating service company and ensuring good shape charge quality.
290
Be sure to read over these points in Section 3 of the manual.
291
For now, let's take a look at another perforating alternative, tubing conveyed perforating.
292
The primary advantage of tubing conveyed perforating is
293
that it provides a method for combining the high performance of large guns with the opportunity to perforate highly underbalanced.
294
This method also allows long pay intervals to be easily perforated because gun length is not constrained by weight or riser height.
295
And highly deviated wells are easily perforated in this manner, since the guns are pushed down the casing.
296
The basic tubing conveyed perforating assembly includes steel hollow carrier guns, a firing head operated by mechanical,
297
hydraulic, or electronic means, a production vent to permit flow into the tubing below the packer after firing,
298
a gun drop sub, which permits the release of the gun assembly into the rat hole,
299
a production packer, and a radioactive tag sub, which permits a through-tubing gamma ray to precisely position the assembly.
300
The firing system may be any of several types.
301
A drop bar system, where a steel bar is dropped down the tubing and strikes a firing pin.
302
a hydraulic firing system where annulus pressure is transmitted to a firing head,
303
a wet connect system which utilizes an electric wire line run through the tubing,
304
or a battery drop which combines the drop bar technique with a battery to provide the electrical firing impulse.
305
The procedure for running a tubing conveyed perforating system is as follows.
306
First, the guns are assembled vertically in the derrick.
307
Followed by the firing head, or heads if a backup system is used.
308
Next, the vent or production valve.
309
The release sub.
310
and the retrievable production packer are then added, unless a permanent packer is already in the well.
311
In this case, the correct length of sealing elements is added.
312
The entire assembly is lowered into the well and positioned.
313
The packer is set, and the proper degree of underbalance established before the guns are fired.
314
Ideally, the shape charges create deep perforations, which are instantaneously flushed clean of debris,
315
as each and every perforation contributes to the flow of formation fluids up the tubing and into the testing facilities.
316
Realistically, though, even the best efforts may require some re-perforating to achieve the expected results. But determining
317
if the newly perforated well is performing up to expectations requires some test data to assess the efficiency of the completion.
318
Tools are now becoming available that will allow the engineer to immediately measure downhole pressure,
319
rate, and temperature, even before the guns are retrieved,
320
allowing for the selective re-perforation of any poorly performing intervals.
321
So let's summarize.
322
In order to maximize our chances for an effective perforated completion,
323
we should remember, perforating underbalance can improve our chances for consistently achieving a high effective shot density.
324
If overbalance perforating is chosen, clean completion fluids are a must.
325
We should use the largest gun possible, given any other constraints.
326
Steel hollow carrier guns are generally the best choice even for through tubing perforating unless the gain in charge size
327
or gun length makes expendable charges preferable.
328
Be certain to flow the well for sufficient time to flush debris from the perforation tunnels.
329
Insist on good depth control techniques and carefully document all perforating activities.
330
Choose a perforating company with a good record of quality control, and safe operating practices.
331
In the next module of the 300 series, we shall consider another important completion activity, acidizing.
332
But for now, please read sections three and four in your manual and work the appropriate exercises.
333
Good luck.
הורד אפליקציה
כל מה שאתה צריך כדי לדבר בשטף
הגיית AIציון לכל משפט
תרגול IPAשלוט בכל צליל
אוצר מיליםבנה את מאגר המילים שלך
משחק אוצר מיליםלמד תוך כדי משחק
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אוצר מילים והערות הגייה לשיעור הזה
שיעור הדיבור הזה ברמה C1 מבוסס על הסרטון “Basic Introduction To Oil & Gas Well Perforating”. המילים שחוזרות הכי הרבה: gun, perforating, charge, pressure, tubing. בסרטון הזה יש 333 משפטים ו-5005 מילים לתרגול Shadowing. הדיבור נמשך 36:33. הדובר שומר על קצב יציב של כ-137 מילים בדקה, קצב נוח לתרגול Shadowing. רק 73% מהמילים נמצאות בין 3,000 המילים הנפוצות ביותר באנגלית, כך שאוצר המילים מאתגר.
אוצר מילים מרכזי בסרטון הזה
15 המילים המתקדמות ביותר בסרטון, עם ההגייה והמשמעות שלהן:
| מילה | הגייה | משמעות |
|---|---|---|
| perforate פועל | חוֹרֵר | |
| collar שם עצם | /ˈkɑlɚ/ | צווארון |
| convey פועל | /kənˈveɪ/ | הוביל, העביר |
| diameter שם עצם | /daɪˈæmɪdɚ/ | קוטר |
| packer שם עצם | /ˈpækɚ/ | אוֹרֵז, אוֹרֶזֶת |
| hollow שם תואר | /ˈhɑloʊ/ | חָלוּל, רֵיק |
| gravel שם עצם | /ˈɡɹævəl/ | חָצָץ |
| fracture שם עצם | /ˈfɹæk.t͡ʃʰəː/ | שֶׁבֶר |
| conductor שם עצם | /kənˈdʌktɚ/ | מְנַצֵּחַ, מנצחת |
| cement שם עצם | /səˈmɛnt/ | צֶמֶנְט |
| drill שם עצם | /dɹɪl/ | מקדחה |
| detonate פועל | /ˈdɛtəneɪt/ | התפוצץ |
| perfective שם תואר | /pə(ɹ)ˈfɛktɪv/ | מֻגְמָר |
| ventilation שם עצם | /ˌvɛntɪˈleɪʃ(ə)n/ | אוורור, הנשמה |
| sandstone שם עצם | /ˈsændˌstoʊn/ | אֶבֶן חוֹל |
Phrasal verbs שתשמעו
| מילה | משמעות |
|---|---|
| turn off פועל | כיבה, כִּבָּה |
דקדוק בסרטון הזה
המבנים שהדובר משתמש בהם הכי הרבה, עם המילים המדויקות מהסרטון:
| מבנה | בסרטון |
|---|---|
| סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה | must be unobstructed · be compromised · has been done |
| הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו | have identified · we've found · has been done |
| משפטי זיקה (Relative clauses) who / which + clause — מידע נוסף על אדם או דבר | carrier, which is · research, which is · log, which has |
הגייה ששווה לשים לב אליה
- הצלילים של “sh” ו-“zh”: perforation /ˌpɚfəˈreɪʃən/, penetration /pɛ.nəˈtɹeɪ.ʃən/, ventilation /ˌvɛntɪˈleɪʃ(ə)n/, detonation /dɛtəˈneɪʃən/, sheave /ʃiːv/
- מילים ארוכות — שימו לב להטעמה: perforation /ˌpɚfəˈreɪʃən/, penetration /pɛ.nəˈtɹeɪ.ʃən/, expendable /ɪkˈspɛndəbəl/, diameter /daɪˈæmɪdɚ/, overbalance /ˌəʊvə(ɹ)ˈbæləns/
צלילים שדוברי עברית מתקשים בהם:
- /w/ — שפתיים מעוגלות, לא /v/: wellhead /ˈwɛlhɛd/, winch /wɪnt͡ʃ/, reservoir /ˈɹɛz.ə(ɹ).vwɑɹ/
- /æ/ — פתוח יותר מה-“אֶ” העברית, לא כמו “a” ב-“cup”: diameter /daɪˈæmɪdɚ/, packer /ˈpækɚ/, gravel /ˈɡɹævəl/, fracture /ˈfɹæk.t͡ʃʰəː/, overbalance /ˌəʊvə(ɹ)ˈbæləns/
- /r/ — הלשון לא נוגעת בשום מקום, לא ה-“ר” הגרונית: perforation /ˌpɚfəˈreɪʃən/, penetration /pɛ.nəˈtɹeɪ.ʃən/, debris /ˈdɛbɹi/, riser /ˈɹaɪ.zə(ɹ)/, retrieve /ɹɪˈtɹiːv/
איך לתרגל עם הסרטון הזה
- הקשיבו לכל הסרטון פעם אחת בלי לדבר, ורשמו את המילים שאתם לא מכירים.
- תרגלו Shadowing משפט אחר משפט במהירות רגילה, וחזרו על כל משפט עד שהקצב שלכם תואם את הדובר.
- הקליטו את עצמכם והשוו למקור, תוך תשומת לב למילים כמו perforate, collar, convey.
מהי טכניקת השאדואינג?
שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.