Emerged Horizontal Drilling Technology and Its Applications ...

Copyright 1999, Society of Petroleum Engineers Inc.

This paper was prepared for presentation at the 1999 SPE Asia Pacific Improved Oil RecoveryConference to be held in Kula Lumpur, Malaysia, 25-26 October 1999.

This paper was selected for presentation by an SPE Program Committee following review ofinformation contained in an abstract submitted by the author(s). Contents of the paper, aspresented, have not been reviewed by the Society of Petroleum Engineers and are subject tocorrection by the author(s). The material, as presented, does not necessarily reflect anyposition of the Society of Petroleum Engineers, its officers, or members. Papers presented atSPE meetings are subject to publication review by Editorial Committees of the Society ofPetroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paperfor commercial purposes without the written consent of the Society of Petroleum Engineers isprohibited. Permission to reproduce in print is restricted to an abstract of not more than 300words; illustrations may not be copied. The abstract must contain conspicuousacknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O.Box 833836, Richardson, TX 75083-3836, U.S.A., fax 01-972-952-9435.

AbstractThe technology of drilling and production of horizontal wellsis probably one of the most significant breakthrough in the oiland gas industry of the eighties. What was considered tenyears ago, as an exotic way of drilling has become reality. Thecontinuous improvement of hardware equipment madehorizontal drilling cost-effective technique for developingreserves, improving productivity and recovery in oil and gasreservoir. Horizontal well technology continues to be at the forefrontof the oil industry. This paper will highlight the Saudiexperience in horizontal drilling. The past ten years have beenan exciting period for those who believed in horizontal drillingapplicability in Saudi Arabia. At the end of the year 1997 overthan 150 horizontal wells have been drilled in Saudi oil fields.There are four major horizontal well applications identified inSaudi Arabia oil fields; 1) Control of coning in relatively thinremaining oil column area, 2) Improving sweep efficiency ofwater flooding program, 3) Improving productivity rate inthin/tight reservoirs and 4) Saving in total development costsin conjunction with previous three applications. This paper presents the major areas of application ofhorizontal wells and more specifically the objectives ofapplying horizontal drilling in different Saudi oil fields.In thispaper, the world horizontal drilling activities along with theSaudi experience will be covered. This paper surveys differentfield examples to show the application trends of horizontalwell technology in both offshore and onshore oil fields. Themain objective of this survey is to demonstrate the

performance improvement of these oil fields after theapplication of horizontal well technology.

IntroductionThe drilling and production of horizontal well have beenrecognized as one of the most important technicalachievement in the oil and gas industry in the last twentyyears. Such technology was considered at the beginning anexotic way of drilling, the economical applicability of whichwas contemplated with some skepticism by reservoir andproduction engineers. A major breakthrough in horizontaldrilling was made with the introduction of the downholeturbodrill/bent sub combination for direction drilling. Rapidadvancement in directional guidance technology such as thedevelopment of steering tools, new tools e.g. resistivity at bit(RAB) and non directional tools involved in measurementwhile drilling (MWD), led to a recent surge in the usage ofhorizontal drilling within the industry.1

The industry demand of horizontal drilling technology hasproduced a variety of new applications and techniques. Duringthe period 1980 to 1984, only one or two horizontal wellswere drilled worldwide per year, but in 1988 that number ofhorizontal had jumped to over 200 wells. Since then a gradualincrease in wells has been noticed with 1570 wells beingdrilled in 1994. Current industry projections are that by theyear 2000 over 5000 wells per year will be drilledhorizontally. Fig. 1 illustrates horizontal well profile withdifferent horizontal section lengths.1 Record for Statoil holdslong horizontal section in Norway (8758 m). The productivityimprovement comparing to that of a vertical well in the samereservoir with the use of horizontal well is controlled byhorizontal section length, target layer thickness andpermeability heterogeneity β as shown in (Fig. 2). In SaudiArabia-Kuwait Neutral zone a 2000 ft horizontal wellcompleted in the upper layers of a 40 years old depletedreservoir would produce seven times more than a vertical wellin the same location, over five years period. The potential ofhorizontal wells has recognized throughout the Middle Eastbut it is in Oman that has seen the most radical changes. Bythe end of 1994 the number of horizontal wells were more

SPE 57322

Emerged Horizontal Drilling Technology and Its Applications in Saudi Oil Fields in TheLast Ten YearsM.S. Al-Blehed and G.M. Hamada,SPE, King Saud University , Saudi Arabia

Dow

nloaded from http://onepetro.org/SPEAPIO

R/proceedings-pdf/99APIO

RC

/All-99APIOR

C/SPE-57322-M

S/1921229/spe-57322-ms.pdf by guest on 20 July 2022

2 M.S. AL-BLEHED AND G.M. HAMADA SPE 57322

than 200 in Oman, 80 in Saudi Arabia, 50 in Abu Dhabi, 20 inKuwait and 6 in Egypt.2 Such kind of success and continuous demand of horizontalwell technology do not come by chance. The main factorscontributed to it are; the physical basis of the concept wassane, the required technology was made available and there wasa market need. The use of horizontal drilling technology in Saudi oil fieldshave been for four targets; 1) Control of coning in relativelythin remaining oil column areas, 2) Improvement of waterflooding program efficiency, 3) Improvement of productivityrate in thin/tight reservoirs and 4) Saving in total developmentcosts in conjunction with the previous three points. The operating companies in Saudi Arabia are committed toapply this technology in a practical and cost effective way byusing the emerged technology. This paper reviews the fields ofapplication of horizontal wells and more specifically in theoffshore and onshore Saudi oil fields. Also the paper discussesthe net benefits gained from the use of horizontal welltechnology in Saudi oil fields.

Horizontal Drilling ApplicationsHorizontal drilling should be considered for any explorationand development programs. The main goals of horizontaldrilling are; maximize the ultimate recovery factor, maximizethe economics of recoverable reserves, sustain a highproduction rate for as long as possible to optimize ultimaterecovery and characterize and evaluate the reservoir inexploration. Certainly not all reservoirs need horizontal wells;some reservoirs should be developed using both vertical andhorizontal wells. Increased production of horizontal wells canreduce the number of wells required for infill or developmentand reduce the number of platforms and/or other structuresrequired in development stages.3-5

Application of Horizontal Drilling to Exploration Up tonow, horizontal drilling technology has been restricted toproduction. Exploration could benefit from horizontal drilling,not as primary tool but as a secondary tool. In other words,once the occurrence of the reservoir and structure has beenproven by conventional vertical drilling, horizontal drillingcan be used to improve the lateral knowledge, and then betterdefinition of reservoir characteristics between vertical wells.Application of Horizontal Drilling to ReservoirManagement The main objective from reservoir managementbasis is the best exploitation of petroleum resources in thedevelopment and production stages. Horizontal drilling candrastically improve production by greater exposure to aproducing zone or zones. A horizontal well may also offerother advantages as decrease of pressure drops and fluidvelocities around the wellbore, minimization of water and/orgas coning, and usually acceleration production. There are several types of reservoirs where production canbe increased significantly using horizontal wells: Naturallyfractured reservoirs, Thin reservoirs, Heterogeneousreservoirs, Reservoirs under urban areas or offshore, Verticalpermeability homogeneous reservoirs, reefs or isolated sand

bodies reservoirs and faulted reservoirs. Fig. 3 shows threecases where horizontal drilling was very successful.Application of Horizontal Drilling to Enhanced OilRecovery In active waterflood and enhanced oil recovery(EOR) fields, the use of horizontal wells can provide thefollowing five advantages; 1) An increase lateral sweepefficiency, 2) An increase of drainage and swept volume inseverely faulted or heterogeneous reservoirs, 3) A reduction inheavy oil viscosity via efficient steam injection, 4) Areduction in heat loss during steam injection, and 5) Areduction in the number of infill wells required for waterfloodor EOR program.Application of Horizontal Drilling to DrainageArchitecture One of the most important openings ofhorizontal drilling is that it has paved the road to the conceptof drainage architecture. Today, it is possible to drill alreadyany type of geometry inside the reservoir and therefore tocreate any kind of flow pattern. The task of reservoir engineerwill be then to define the proper drainage architecture adaptedto the fluids, the production mechanism and the characteristicsof the formation. The driller will have then to implement iteconomically.6

Horizontal Drilling Applications in Saudi Oil FieldsThe producing fields of Saudi Arabia contain the largestconcentration of oil reserves in the world. Ghawar is theworld’s largest onshore field and Safaniya is the world’slargest offshore field. In total, more than 50 fields haveapproximately 250 sandstone and carbonate reservoirs. Fig. 4shows the distribution of offshore and onshore fields in SaudiArabia.7 Saudi Arabia contains an estimated remaining provenreserve base of over 257 billion stock tank barrels of crude.These reserves represent 25 % of the world proved reserves.This large crude oil reserve has positioned Saudi Arabia toapply horizontal well technology to be able to improvereservoir performance, to cost effectively implement thedevelopment projects and to explore for and produce fromdifficult oil and gas formation settings. The maturing of specialized drilling techniques has nowplaced the world in a position to more fully exploit horizontalwells. Fig. 5a illustrates the boom in horizontal drillingactivity in the world and North America in the 90’s and Fig.5b shows the rate of growth of horizontal drilling activity inSaudi Arabia. The comparison between (Fig. 5a) and (Fig. 5b)demonstrates that oil companies in Saudi Arabia are makingoptimum use of the emerging world experience in this newand exciting horizontal well technology. In Saudi Arabia,horizontal wells have been used in offshore fields and onshorefields to solve their arisen problems.8

Offshore FieldsBerri Field Berri field is located both onshore and offshorealong the western edge of the Arabian Gulf. Its 1994 dailyproduction rate was about 300,000 STB. Berri field is the firstfield to have horizontal drilling technology applied. Thecarbonate nature of the reservoir improves hole stability and

Dow



RC

/All-99APIOR

C/SPE-57322-M


SPE 57322 EMERGED HORIZONTAL DRILLING TECHNOLOGY AND ITS APPLICATIONS 3I N SAUDI OIL FIELDS IN THE LAST TEN YEARS

makes possible open hole completion hole that give two timesconventional well rates. A great advantage of horizontal wellsover verticals is an increased exposure to the wellbore of thinoil columns and /or tight rock sections. An existing high watercut Hanifa well was reentered and sidetracked. Fig. 6 shows ahorizontal section of more than 1500 ft. was drilled along thetop of the reservoir above the OWC and away from the watercone. The well has since produced very little water.

Marjan Field Marjan field is located 9 miles offshore in theArabian Gulf. Its 1994 daily production was about 400,000STB. The field consists of four main areas: Marjan, Lawhah,Maharah and Hamur with 13 oil bearing reservoirs. The Khafjireservoir is the only zone on production. It suffers from astrong water drive and a large gas cap. The objective of 13horizontal wells drilled in this zone is to reduce coning of gasand water. The target rate of these wells is twice that of theconventional well. Fig.7 shows the profile of a horizonal wellin Khafji zone. Also three horizontal wells have been drilledKhafji thin stringers sands. These wells have shown thathorizontal wells can be cost effective way to improveproductivity in thin reservoirs.Zuluf Field Zuluf field is one of the northernmost field inSaudi Arabia and is located about 35 miles offshore in theArabian Gulf. Its 1994 daily production was about 500,000STB. The field contains 8 oil and gas bearing reservoirs.Khafji reservoir is the main reservoir and it has string waterdrive and a gas cap. Three horizontal wells have been drilledin the Khafji main sand to control gas and water coning. Thus,the productivity has reached four times that of nearby verticalwells. In Khafji stringers, three horizontal wells have beendrilled to exploit these thin sands. Fig. 8 shows a horizontalwell in Khafji stringers. Production in these wells has beendoubled that of the offset vertical wells. Safaniya Field The Safaniya field is the world’s largestoffshore oil field. Safaniya field is divided into three areas:North, Central and South. There are 8 producing reservoirs. Its1994 daily production was about 960,000 STB. The Safaniyaand Khafji reservoirs are the main producers. The objective ofhorizontal drilling in this field is to reduce coning in the areaswhere there is a thin oil column. Fig. 9 shows horizontal wellprofile in Safaniya sand. Six wells have been drilled inSafaniya fields, two in Khafji reservoir and four in Safaniyareservoir. All wells were drilled to reduce water coning andadverse mobility ratio. These wells have outperformed theconventional wells by a factor of two. Abu Safah Field Abu Safah field is located offshore 30miles from mainland Saudi Arabia. Its 1994 daily productionwas about 150,000 STB. The Arab-D carbonate is the mostproducing and the only developed reservoir in Abu Safah. Theobjectives of horizontal wells in Abu Safah field are toproduce wedge oil from flank areas by targeting thin oilcolumns located above oil water contact and to improveproductivity of relatively tighter zones at the top of thereservoir. Fig. 10 shows horizontal well in Arab-D formation.

Five horizontal wells are planned to increase the drainagefrom thin oil column in the south flank that is relatively tightand underlain by water.

Onshore FieldsGhawar Field Ghawar field is the largest producing field inthe world. Its 1994 daily production was about 5,000,000STB. The Ghawar contains several producing reservoirs. Allreservoirs are carbonates, the main producing formation is theArab-D sequence. Significant number of horizontal wells weretargeted in Ghawar field to increase the efficiency of thewaterflooding program, by improving sweep efficiency andinjection performance, and to capture additional oil.Application of horizontal drilling to producers has just begunin Ghawar. Fig. 11 illustrates a model of a horizontal well inGhawar field.Abqaiq Field Abqaiq is one of the maturest oil field in SaudiArabia. This onshore field was discovered in 1940 andproduction begun in 1946. Its 1994 daily production was about650,000 STB. Abqaiq contains four producing bearingsequences. Horizontal well were drilled in Arab-D formationin area of thin oil column to increase the efficiency of thewater flood and capture all available oil. Vertical wells in suchareas have high water cuts and are produced at restricted rateto avoid water coning. Horizontal wells have higher rates. Fig.12 shows a horizontal well at the top of a thin oil column in ofArab-D, horizontal length is over 2000 ft.

Economics of Horizontal Drilling in Saudi ArabiaBy the end of 1994 over than 80 horizontal wells have drilledin Saudi Arabia at a total cost of more than 350,000,000 $.Fig. 13 illustrates the distribution of these wells according tothe fields (offshore & onshore), type of well as producer orinjector, nature of reservoir (sandstone or carbonate) andaccording to the objective of the horizontal well beingplanned. Operating companies specially Saudi Aramco arecommitted to use horizontal well technology as a costeffective and reservoir performance technology. Fig. 14depicts very well this economic commitment. Relative costcurve of a horizontal well to a vertical well is approximatelyclose to one in offshore and offshore fields in the period 1992-1994.

Conclusions 1. Horizontal drilling technology is the most effectivelyexpanding technology in the last ten years to improveproductivity, control adverse and damaging reservoirconditions and enhance recovery of oil and gas reservoir andalso to explore and produce oil and gas under difficultgeographical and geological settings 2. Application of horizontal well technology in SaudiArabia has accomplished the planned targets:

• Control water and gas coning problems in offshoreand onshore fields

Dow



RC

/All-99APIOR

C/SPE-57322-M


4 M.S. AL-BLEHED AND G.M. HAMADA SPE 57322

• Improve the efficiency of waterflooding programs • Increase productivity of tight reservoirs • Increase productivity of thin oil columns reservoirs • Improve capacity of producing wells • Reduce the total number of infill and developmentwells.

• Reduce total drilling, flowline, facilities and water/gashandling costs.

Reference1. Ginnesini, J.F.:’’ Horizontal Wells: An Overview’’ OAPEC-IFP

Workshop on Horizontal Drilling and Application, Paris, June23-25, 1992.

2. Petit, H. and Lesage, G.:” Adapted Screening Procedure, Key toSuccessful Horizontal Well Engineering Projects’’ OAPEC-IFPWorkshop on Horizontal Drilling and Application, Paris, June23-25, 1992.

3. Schlumbergure Oil Services:’’ Horizontal Well Technology’’Horizontal Well Technology Seminar, Cairo, February 10-12,1991.

4. Hamada, G.M.: ‘’ Horizontal well Technology in Egypt” EGPCSeminar on Horizontal Well Technology, Cairo, July 26, 1996

5. Renard, G. and Sabathier, J.C.:’’ Integration of HorizontalDrilling into Reservoir Management Practice’’ OAPEC-IFPWorkshop on Horizontal Well Drilling and Application, Paris,June 23-25, 1992

6. Legros, E.: A Technical Success for Elf Aquitaine: HorizontalDrilling’’ Intl.Petrol. Gaz, Chim, April 1983, pp. 56-59.

7. El-Malik, M.:’’ Notes on Petroleum Engineering’’, King SaudUniversity, 1998

8. Saudi Aramco:’’ Horizontal Drilling in Saudi Arabia’’ SaudiAramco Pub. Summer, 1995.

Dow



RC

/All-99APIOR

C/SPE-57322-M


SPE51322 Emerged Horizontal Drilling Technology and Its Applications in Saudi 5

Oil Fields in the Last Ten Years

716-286 firadu

Pay Zone

--zFT s

Fig.l- Three horizontal well profiles with different lengths (Ref. 1)

17 c

16 -

15 -

14 -

13 -

12 -

11 -

10 -

9-

8-

7_

6-

5-

4-

3_

2_

lf_

p= +k J- V - h=20n -_---. h= lOOft ----- hz20Oft

0 rc- , , ) , , 1 1

0 L

400 800 1200 1600 2000

L vu

Fig.2- Relative productivity versus horizontal section lemgth (Ref. 3)

_

Dow



RC

/All-99APIOR

C/SPE-57322-M


6 M.S. AL-BLEHED and G.M. HAMADA SPE 57322

\ Tapping ciiiferenf Pmducing horizons. ‘\

\ ‘\

improving productton from hetrogenems reservoirs

\

\

\

‘\ \

\ ‘\

‘\ \ Perletrafing a series of

‘l ‘\ I

“\

,

Fig3- Three examples of horizontal drilling applications (Ref. 4)

Dow



RC

/All-99APIOR

C/SPE-57322-M


SPE 57322 Emerged Horizontal Drilling Technology and Its Applications in Saudi Oil Fields in the Last Ten Years

7

_ ‘. A-L. * )‘-‘_‘.I.2 i..__ _ __ __~__ =.---~~_-~J-__-~~.~~._

.L __ . . -_ .- ._

- -__.-

Fig.4. Oil fields and facilities in Saudi Arabia (Ref. 7)

Dow



RC

/All-99APIOR

C/SPE-57322-M


8 MS. AL-BLEHED and GM. HAMADA SPE 57322

World Horizontal Drilling Activity WELLS PER YEAR

m North America

a- World and North America

b- Saudi Arabia

Fig.5 - Number of drilled horizontal wells (Ref. 8)

Dow



RC

/All-99APIOR

C/SPE-57322-M



9

Fig.6 - Horizontal well drilled in Hanifa formation, Berri field (Ref. 8)

Fig.7 - Horizontal Drilled in Khafji sand, Marjan field, (Ref. 8)

Dow



RC

/All-99APIOR

C/SPE-57322-M


M.S. AL-BLEHED and G.M. HAMADA SPE 57322

Khafji Main Sd_

i

I

Fig.8 - Horizontal wells drilled in Kafji sand and stringers, Zuluf field,(Ref. 8)

+. _ .

- Fig.9 - Horizontal well drilled in Safaniya reservoir, Safaniya field, ( Ref. 8)

Dow



RC

/All-99APIOR

C/SPE-57322-M



11

-6,400

-6,500

-6,700

POROSITY , 0 0 0 TOP OF ARAB-D

Fig. 10 - Horizontal well drilled in Arab-D, Abu-Safah field, ( Ref. 8)

Fig. 11 - Horizontal well drilled in Ghawar field, ( Ref. 8)

Dow



RC

/All-99APIOR

C/SPE-57322-M


12 MS. AL-BLEHED and G.M. HAMADA SPE 57322

Fig. 12 - Horizontal well drilled in Arab-D, Abqaiq field, ( Ref. 8)

WEil LOCATIONS

WELLTYPES

,

q ONSHORE

w OFfSHORE

(r d

a PRODUCER

n WATER MJKTION

m CARBONATE

n SANDSTONE

WELL APPLICATIONS

n RATE ENHANCEMENT

H WATER FLOOD ENHANCEMENT

•j SWEEPIMPROVEMENT

l CONING CONTROL Fig. 14 - Relative cost of horizontal well ,

offshore and onshore fields, (Ref.@

Fig. 13 - Distribution scale of horizontal well drilled in Saudi Arabia, ( Ref.@

Dow



RC

/All-99APIOR

C/SPE-57322-M


Emerged Horizontal Drilling Technology and Its Applications ...

Documents