Paper Radial Jetting

7/24/2019 Paper Radial Jetting

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RADIAL JET DRILING ATAU RADIAL

DRILINGAgustinus B, Aisyah E, Aldi F,Alifa F,Chairunisa Y,Destia !,Fadhil

",I#an $A,Aditya %&

References : http://www.drillingcontractor.org/low-cost-radial-jet-drilling-helps-

revitalize-40-year-old-oileld-233

Upward trends in oil prices and the

proliferation of new technologies are

enabling operators to capitalize on

new opportunities. Horizontal

drilling and completion are opening

up reserves in fields that were not

previously economically viable. This

trend is not limited to previously

undeveloped fields or by lithology.

Operators are also able to gain higher

recovery from old fields where

production has declined over time,making new opportunities for

matching technology to economies

of scale for such marginal proje

igure !" The radial jet drilling

procedure begins with the removal ofproduction e#uipment from the well

and rigging up the coiled$tubing unit.

The coiled tubing is lowered down

the well to the target formation, and

the cutter perforates the casing and

cement. % high$pressure hose is

lowered downhole, and drilling fluid

is pumped to erode the reservoir and

drill the lateral.cts.

This article outlines the re$

completion of a portion of a &'$year$

old field using radial jet drilling

()*+. The reservoir is a carbonate

formation with low permeability. The

combination of low permeability,

low productivity from traditionalvertical completions in a thin net pay,

and lack of low$cost techni#ues to

improve well productivity caused

production to dwindle. %fter

ac#uiring the lease in late -'!', the

new operator implemented a

program of )*+ and acidnitrogen

fracturing to enhance production.


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)*+ is a low$cost, environmentally

friendly method to drill numerous

small$diameter horizontal laterals

from a vertical

or near$vertical wellbore. /t works in

both new and old wells that already

have a production history.

The article summarizes the workover

effort and production data before and

after the workovers. The results show

that nearly a two$fold productionincrease was obtained, and it can be

clearly seen that )*+ can be a viable

alternative to improve productivity

of shallow reservoirs that still have

significant oil in place.

0ackground

The +onelson 1est field, located in

2owley 2ounty, 3an., covers about!,-'' acres. The target formation is

the %ltamont limestone, which is in

the upper part of the 4armaton

group in the 4iddle 5ennsylvanian

series. /t is a fine crystalline

limestone that varies in color from

light brown to brownish white. The

formation displays some pinpoint

and vugular porosity. ormationporosity typically varies from !67 to

-'7 while permeability varies from

!$!' millidarcies and net pay

thickness varies from 8$!' ft. 9as

drive is the primary driving

mechanism.

igure - " The nozzle:s forward spray

cuts the formation while the rearward

spray accelerates the nozzle:s

progress into the rock and circulates

cuttings. The diameter of the nozzle

varies from '.6 in. to '.;6 in. and is

appro


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damage and recover more resources

from stripper wells.

igure = " *et$drilled holes vary in

size. >ach of the holes was drilled

into sandstone with radial jet drilling.

)*+ technology is oriented toward

e


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1hat is )*+E

/nstead of being drilled with aconventional bit and drilling mud,

)*+ uses high$pressure water, diesel

or acid to be e


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+ifferent companies offer this

service commercially, so procedures

vary depending on the operators and

their proprietary e#uipment. Dome

firms mill the casing and then jet the

holeA others mill the casing, turn the

deflector shoe, mill another hole in

the casing, and then jet the holes out

into the formation. Others use

abrasive sand in the jetting fluid,

allowing them to eliminate the use of

a cutter and use this sand to cutthrough the casing instead.

undamentally, however, these

procedures follow the same essential

pattern of milling the casing and

jetting the hole.

)*+ >#uipment

. igure 8 /n the past decade, the

+onelson 1est field has seen in an

upward trend in production and the

number of wells online. %fter -'';,

production steadily increased from

less than !,''' bblsyear to

appro


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drilled holesA each was drilled into

sandstone via )*+.

There are three primary penetration

mechanisms that drill the rock in

)*+" erosion, pore$elastic tension

and cavitation. The high$pressure

fluid jet erodes the formation by

pumping a relatively small amount of

water at high pressure and high

velocity through a very small hole.

5ore$elastic tension occurs when

high$pressure water enters the pore

space, increasing the pore pressure

and causing the rock to fracture. The

sudden increase in pore pressure

produces cavitation" fluid$free

bubbles are formed in the areas of

lesser pressure and immediately

implode, causing shockwaves that

enhance the fracturing of the

formation.

/n )*+, the 2TU resists the weight

of the hose hanging in the well, as

well as the force created from the

backward$facing jets in the nozzle.

%s a result, the high$pressure hose is

subjected to a significant amount of

tension, which is beneficial for the

operation. This tension pulls the

high$pressure hose tight and ensures

a straight bore. These forces are

illustrated in igure &.

+rilling luids

The fluid pumped through the high$

pressure hose to the nozzle varies

depending on reservoir lithology and

formation fluid properties. /n most

cases, water is sufficient as it has

obvious advantages as an )*+ fluid.

/t is a cost$effective fluid, readily

available, easily disposable and has

no HD> issues. However, in water$

sensitive formations, diesel fuel may

be used to drill the radials. +iesel

fuel also has solvent properties that

may be advantageous for wa


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igure G " 5roduction from two new

wells that were part of a program to

produce remaining recoverable

reserves were completed with radial

jet drilling ()*+ and accounted for

;'7 to G'7 of total lease

production. 5umps on two old wells

were replaced before 4arch -'!-,

during which total field production

reached a high.

The primary benefit of )*+ is its

economics. /t can be a cost$effective

method to complete vertical wells to

perform like an open$hole horizontal

completion. +rilling a new or

sidetrack horizontal completion with

a rotary rig re#uires pulling the

tubing, killing the well and drilling

large$diameter completions at

traditional rates of penetration. These

e


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igure !' " +ata before and after the

treatment indicates that old wells are

producing more oil K with well

production doubling K and making

the )*+ and acid fracturing

campaign a success.

The biggest limitation of )*+ is that

while a jet$drilled lateral begins to

mimic the performance of a

horizontal completion, it is not a

horizontal completion. There is no

way to complete the lateral with a

liner as it is impossible to run casing

into the lateral. 4anaging future

production from the well could be

very difficult. Dhould the operator

want to shut off flow from the

lateral, doing so could be impossible.

)eentering the lateral after it has

been drilled also could be very

tricky, and pumping some type of

s#ueeze down the lateral could be

very problematic.

%dditionally, there are no

surveillance options. /f the lateral

begins to produce water or gas, there

is no way to diagnose which part of

the lateral is contributing to the flow

because standard logging tools likely

won:t fit into the lateral.

+irectional control of the lateral is

also very difficult. This can make

reaching specific targets challenging

and presents the risk that the lateral

could e


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recovery factor, as much as '.B6

million bbl may be recoverable.

5roduction History

The +onelson 1est field commenced

the production in !B8;. +uring !B8G,

the field produced G=,''' bbl from

!= wells, after which production

began to decline. +uring !B;=, the

field produced only !&,G6G bbl. Over

the past !' years, production from

the field has been very low. rom-''' to -''B, the field averaged

!,'== bblyear, with a ma


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Table !" )adial jet$drilled laterals

were drilled over several weeks, and

total monthly field production after

the workovers significantly

increased. 5rior to the workovers, the

field averaged about !6; bblsmonth,

and after the workovers, the field

averaged B=G bblsmonth.

The field was originally developed

with vertical completions. These

completions were followed by

acidnitrogen fracturing. The wells

were not all identically treated, and

those treated with between !','''$

!6,''' gal of acid and !-6,''' 4cf

nitrogen produced at higher rates

than other wells fractured with less

acid.

ield )edevelopment

% new operator ac#uired a =-'$acre

lease in the field in late -'!' and

began to develop a program to

produce the remaining recoverable

reserves. The overall plan consisted

of stimulating the e


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e


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years before the )*+ work was !8

bbls of oil per month. %fter the

treatments, the per well production

averaged =G bblsmonth.

igure G is a plot of total field

production and production from both

the two new wells and seven old

wells. 9enerally speaking, the two

new wells

account for ;'7 to G'7 of total

lease production. These two newwells came on strong, and as the

adjacent pressure has depleted, their

production has declined. The

remaining -'7 to ='7 of current

lease production has been

consistently better than -'' bblday.

igure G does indicate abnormally

high production during 4arch -'!-.

*ust prior to this period, the pumps

on the two old wells were replaced.

The pump replacement resulted in

short$term production benefits that

are primarily responsible for the

production increase. +uring *une

-'!-, production from both the old

and new wells was down slightly.

+uring this time, there were

production disruptions associatedwith additional infill drilling and

bringing those new wells online. The

before and after comparison of old

well production is shown in igure B.

The step$change in production after

the )*+ and acid fracturing is

evident in igure !'. 5rior to )*+,

the wells struggled to reach -''

bblmonth. %fterwards, production

reached nearly 6'' bbl one month

and is consistently in the range of

-6' bblmonth. Table - presents

monthly production data for the old

wells before and after the workovers.

rom -''G to -'!', the field

averaged !6; bblmonth from the old

wells. or the nine$month period

after the )*+acid fracturing

treatment, the wells have averaged

-8& bblmonth. However, much of

the variation in historical production

is due to fluctuating well count.

+uring periods when wells were shut

in, production was down. Table =

summarizes average monthly

production per well, and igure !! is

a plot of this data.

%fter normalizing for well count, the

success of the treatment is evident.The per well average production

rates for the three years prior to the

)*+ work was !8 bblmonth of oil.

%fter the treatments, the per well

production rate is on average =G

bblmonth. >


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The data indicates that the old wells

are producing more oil, and on

average, each of the producing wells

is producing more oil e


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factor. /t is probable that the long

horizontals, though small in

diameter, are able to aid fracture

propagation.

our laterals per well, each

penetrating 8'' ft into the formation,

could be a significant head start for

fracture propagation. 2onversely,

they could also hinder fracture

propagation if the laterals themselves

contribute to leak$off and the fluid

can:t sufficiently break down the

formation. %dditionally, the effect of

acid in limestone is well understood

to be of a significant benefit.

/t is also possible that the orientation

of the laterals is important. 1hereas

hydraulic fracturing tends to

propagate fractures parallel to the

formation:s natural fractures, )*+can enter the rock perpendicular to

the natural fractures and open up

flow through them. The particular

mechanism that caused the

productivity increase at this field is

uncertain, but it is probable that it is

a combination of some of these

factors.

2onclusions

5rior to the lease changing hands,

this field was essentially shut in, with

only sporadic production that

amounted to about !6' bblmonth.

Two new wells were drilled, which

were completed with )*+ laterals

and fractured with acid and nitrogen.

>ight old wells received a similar

)*+ acid fracturing treatment. Only

one of the old wells that were treated

failed to produce oil after the work.

%fter this work, the field average

production was more than B''

bblmonth. %nalyzing the production

from the new wells and the old wells

separately indicated that between

-'7 and ='7 of this total production

came from the old wells. This

represents a two$fold increase in

production from the old wells on an

average per well basis.

+espite its limitations, )*+ can be

effective for completing both new

and workover wells with radials up

to !,''' ft due to its low

environmental impact, economical

enhancement of reservoir

productivity, suitability for many

formation types, enhanced

effectiveness of subse#uent wellstimulation treatments, and the speed

at which laterals can be drilled.

uture work might focus on

comparing the productivity of jet$

drilled laterals to traditionally drilled

horizontal wells, skin factors, and

comparison of theoretical

productivity predictions of horizontal

wells to actual productivity of

horizontal jet drilled laterals.

D5>/%+2 !8=&'6, ?ovel

Techni#ue to +rill Horizontal

Jaterals )evitalizes %ging ield,I

was presented at the -'!= D5>/%+2

+rilling 2onference, 6$; 4arch,

%msterdam.

)eferences


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%bdel$9hany, 4. %.A Diso, 4.A

Hassan, %. 4.A 5ierpaolo, 5A, and

)oberto, 2. -'!!, ?ew Technology

%pplication, )adial *et +rilling

5etrobel, irst 1ell in >gypt,I D5>

-'!!$!8=, !'th Offshore

4editerranean 2onference and

> !';=G-, D5>

Jatin %merican and 2aribbean

5etroleum >ngineering

2onference,0uenos %ires, %rgentina,

%pril !6 $!G.

0uckman *et +rilling, -'!', Jeading

/nnovators in *et +rilling

Technology,

www.buckmanenergyservices.com.

+ickinson, 1. and +ickinson, ).

!BG6, Horizontal )adial +rilling

Dystem,I D5> !=B&B, D5> 2alifornia

)egional 4eeting, 0akersfield,

2alifornia, 4arch -;$-B.

+ickinson, 1.A +ickinson, ).A

Herrera, %., +ykstra, H.A and ?ees, *.

!BB-, Dlim Hole 4ultiple )adials+rilled with 2oiled Tubing,I D5>

-=8=B, Decond Jatin %merican

5etroleum >ngineering 2onference,

// J%5>2, 2aracas, Lenezuela,

4arch GM!!.

+ickinson, 1.A +ykstra, H.A

?ordlund, ).A and +ickinson, ).

!BB=, 2oiled$Tubing )adials 5laced

by 1ater$*et +rilling" ield )esults,

Theory, and 5ractice,I D5> -8=&G,

8Gth D5>%T2>, Houston, Te


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Towler, 0.. -''-. undamental

5rinciples of )eservoir

>ngineering,I Te

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