unconventional gas shales development technology and policy issues ppt

Unconeationa Gas Shales Deselopment,Techaslgy and Pale ees Contents Background LUnvonventonal Gas She Resources inthe United Sats, ‘Barnet Shale Formation ‘Natural Gas Resace Poe Souties

Congressional

ES Research

Service

Unconventional Gas Shales: Development,

Technology, and Policy Issues

Anthony Andrews, Coordinator

Specialist in Energy and Energy Infrastructure Policy

Summary

Inthe past, he oil and gas industty considered gs oeKal ight, ingermae le

tnoconomical to produce: However advances in diectional well dling and rsercir

stimulation have Uamatically increase gas pradetion fom unconventional sles The Unite Stes Geological Survey estimates thu 20 elon cubic fst of url gas may he tecinially reccerale rom thes shales Recent high natal gs rics have als tila eres in

‘leseleping gs shales, Alb natal 2 ries Cll ranean 2009, these a

expectation lai the demand for natal ss il increase Developing these shales coms ith Same controversy Uh,

Hydralicallytracuad wells are also subj to Yarious sate regulations Historically the EPA lực net regulate racic factoring an the 2005 Energy Policy Aotcxempted hướn he feuctusing om SDWA repulation Recently inrxced bils wool make hydraulic tactupne sult o regulation ander SDWWA, while anober hill would air the current spur

Unconeationa Gas Shales Deselopment,Techaslgy and Pale ees

Contents

Background

LUnvonventonal Gas She Resources inthe United Sats,

‘Barnet Shale Formation

‘Natural Gas Resace Poe

Soutiest Regional Gas Supply and Demand

Groundvater Resource sts

-Marcelos Shale Formation

Natural Cis Resource Pott

Nontheast Resin Natal Gas Sapply and Demin

Groundater Resece Isis,

Dring and Developmen Tecknlogy

Fodor and State Las aa Regultions Affetng Gas Stale Develop

Surface Water Quality Proection

Groundvaice Quality Prection

Safe Drinking Water Act Author

Unvereroua Injection of Waste Eis

State Water Quality Laws

State Water Supply Managencnt

‘Congressional Iter

For Further Reading

Figures

Figure 1 Major Shale Basins in the Conterminos United State,

Figure 2, Bend Arch Fors Wort Basin Avea

Figure 3, Mor Natoral Gas Teaspoon Corridors nthe Conteris Unite States,

‘oro Resa Sie

2 45

Figure 4 Aquifers athe Ben Atch-Fort Wort Basin Arca

Figure 5, Maeelus Shale Fovmation Thiskness

Figure 6, Devonian Shale Cross Seton

Figure 7, Devonian Shale Uncovered Resouree Potent

Figure 8, Nonheast Region Natural Gas Pipeline Nework

Figure, Sole Souree Aquifers i the Appalachian Noma Region

igure 10, Rotary Drilling i

Figure 1! Directional Del

Figure 12, Hypshetcal Well Casing

Figure 13 Hydraulic Focsure Jo

`" `

Figure 15, Federal Lacs Ovrlying Natta is Resoures ofthe Appalachian Basin

Tables

Table I Shale Gas Bonus Bids, Rents, and Royalty Rats on

Table 2 Shale Gas Bonus Bids, Rents, and Royalty Rats on Private Land in Selected

"

48

mm

Unconeationa Gas Shales Deselopment,Techaslgy and Pale ees

‘the Appalachian basin inthe nogitaetern United State pnt pests te cess

‘com caonal gs resoue inthe Unit Stats, Other sale formitons such asthe Haysville shuts studing Texas and Leaisian, fave als atractsd ntrest as have some formations in

‘Canad, The esoutes potential ofthe sales has significantly increased the tal gas serve estimates inthe United States

Rect high natural gas prices had stitulated interest in as shales abthangh prices fell Below S0 10 per mion Bs (mt) in simmer of 2000." Despite the carry ls natural sas ries, there sam expoczation ạt the dma fr staal gs wal nerease and hat

Unconventional gs shales wil pa majo le n meoing hề ieteatol dena For ata gas

“Thoshale's development it subj of controversy, however, The patent economic Benefits Feo bs he ding acti al he Tease and yay payments compete wth He publ's oncetn for environmentally safe Willing practices and protection of gtowndater a suas Ditetional dling ana “hyralie eating” ae instrumental in explekng tis source

Although oi and gas developers have appli these techoloyies in conventional ot Hels for Sometime they have only ceenlyheyun applying then to unconventional gs shals As with

‘il and gas production generally, ga shale development spinal sujet t tte law aad Fegulation, hough provisions of two relevant Keseral ls —the Safe Drinking Water ct {SDWA) an the Clan Water At (CWA) —als apply, Regulation of wel construction diflers

hy stat, a eral nw currently xen from relation the ergot injection di hit foe dec Hsctiins purines Two rover intrdiced bills would set hyde

‘acting to regulation under the Safe Drinking Water At, while hia ll woul aiea the ceInenf SDWA exemption Tere has bee a increase i rept of abe concerns that hy dale Fracturing poses a peril rsk to water wells anu thus domestic daking water supp The

‘concern that the chemicals used pose a pote riko groundwater quality and the actusing Thay damage opiers.Crics maim hat the large quantities of water that Rydal fracturing

‘consumes tu tax Jal and reponal water supplies and that disposing the flowack”exracted from the shal afer fectring may alfet surface water and groundwatr quality Undcetaning the tecea pineipls of welding, well corsicton, aa timation maths report

to assessing te conser that have arisen over the shuks development

‘Gas shale development takes place on bot private and state lan Roynly tae, res, and Signing hss pdt ste Sr private trons ry In Texas where sa as hale evelopment takes place, the ates are gencrally higher Although federal Inds oyerbe some Postions ofthe Mares, restrictions to dailling and fw cesoarce potential may make then ess {sirable (o develo Inte eae of splitesae nds, which seer mitre fr surface

‘ovunership the minera-owrr rains the right acces the land for development Lanvunees may hủ he aire ofthe mineral-nsmner” acces his, ak tem decompensation he acess Furthermore they may have wo contend with long-term easements forthe gathering pipelines hat

‘connec he well to natural gas rnsmsson ines, The states orgie reclamation ofthe ting sites to varying degre

Inslences (ey are aso ealed “cortinuous-4ype deposits In eomeast, conventional petroleum satura gas cccurn probs sandstone anil arbonate reservoirs Under hydrodynamic

pressure exci hy Water, the petoleum migrated upward fonts ogaaic source uni an Ferma cap-rck (sci a shal) rappin the reserve rock The "essa ha

aceumblaio oer the pare has heen the sore of nest feuded aut As

Unconentonl Shales Deeopmt, Technology an Policy ses

Figure 1 Major Shale Basins in the Conterminous United States

Source: US DOE Of Fos rag Mos Sl Gat Dept nh Unig See A Pic

[Natural gas prodtion nthe Unite States had ben dclining uni cently ARer peaking at

‘carly 24,2 etn 200), produeio deeine l 288 tf by 2005, The decline had overs by

2008 when production rose to over 26 te (Gulf of Mesieo offshore gas production continues to Aecine, however, ad the 2.3 tet produced in 2008 was only 47% ofthe 2000 Gulf production level)

Since 1990, US gas production inecase in large part dc to teal increasing production of

‘unconventional sources, The U.S, Geological Survey (USGS) estmales that about 200 tf of ratral gas may he technically reeoverahle fom the sil wih a ecovery Factor of 10% to 15%"

“Those sources include shale gas, coalbed methane, and tight sands Unconventional gas

roxcton neease 65% from 1998 (5.8 tefiyear to 2007 (8.9 year

US BOE Energy lfmton Adina, Nat! Ga vgtr Natl Ga Sty, 29,2008, panos te gosh EPO FGM ma AhMm

pinned poten teat poacons

Navi Coming Uncommon! Ga Supp Twas Pcs Cane Maing Sn Francis, CA

‘Natal eas poesin nthe “big 7 shale plays (Anim, Barnet, Devonian, Fayestvile

Woodford Hayne Marcel) could reach a estate 27 39 etd iin 10 0018 sears! Development however, his been uneven inthe Marssis Aoagh proton deta are incomplete at ost pons indicate dhat Pennsylvania leads de region in proueing wel with

‘West Virginia and Obi ane, Nevigantexpocs thatthe Marelle asin wl be he et significant pos shale py I appes ptenally larger Han the over basin alsady developed

Barnett Shale Formation

The Bart Shale formation s Missssippian-age Hack shale that has a high organic coment." Ie edetie 5,000 sare mies of the DallayFont Wort aca of eaas (primi in te Fort Worth [Basin to dep of 6301 0 8,300 fet (Soe igure 2)

Natural Gas Resource Potential

The Bart Shale play s reportedly the most astve natal gs pai the Uni Sats wth as

‘many 36173 dling igs at ork the past sear The USGS estimated tht as much as 26.7 et

‘tal gas col be prescot in contints accumulations es aonasocite is trap in strata

‘ot ofthe tse Barat Shale Assess Units (AU)—the Creater Newath East Fra: aster

‘Comins Barnet Shale Gs AU and the Extended Conkngus Barnet Shale Gas AU"

Calletvely, th nits 38 comprise the Bend Ateh-For Worth Basin

‘Conprssiona Rewer Broke

lyme, Tecnology an Policy lesce

“The area has proce ol and gas since te arly 1900s, but mostly From conventinal

reservoirs There are over 8.000 wells producing gas fromthe Barnet formation" Gas

Production increased fom 4 million cubic feet pe day (mmcday) in 1098 0 over 3 billion tieTeeUfay (beday) in 2007; an increase of over 3.000%

Figure 2 Bend Arch-Fort Worth Basin Area

‘The Newark Eastfield ofthe Barnett hasbeen the ages geprodicig field in Texas since

200, apd anked asthe secon highest US gas-producng Held in 2005, Gas prdtion rose Tran le than 11 bof of tural 20 in 193 to about ND et by 2005 From anuazy 1993 to January 2006, cumulative gus preducton meso abut Le, The Newark East ld proven ens reserve estimates range fron hacen 25 and 3

Southwest Regional Gas Supply and Demand

Several major pipdins corridos transport natural gas inthe United States, Five major pipeline Foes exten fon he procing area nthe Southwest anal more daa 29 of the majo arta Piclines onsite in the Southwest Region (Soe Figure 3) In purticular, major ppline nstworks, consueted ater World War Il anspor as Fam th Gulf of Mexico regon the [Noha ro the Southst tothe Northeast, a Tom the Sotwest the Mice

Cue pipeines have the capeity to transport 3 natch as 4.2 et per dy frm he esion 628 tothe Southeast Region, 2 tothe Cental Region, 13% to the Western Reon, andthe rat to Metieo la esponse increas natu gus production and sa), Tarie9lxl from the Bart Shale, the Southwest reson ecwatly expand its pipeie atest on large-scale Wy

2008, 30 now pipelines comprising t3%2 milks reached completion neacy double the previus ears Thincen ofthe nv pipelines related to or expand the nrast Texas area to ne

‘vclpinent of gas supplies fon the Bara, Woodford oe Fayetteville Shale formtions The remaining pipelines supper increase! igueted taal pss (LNG) imports hua Tess marine termina

LUnconentonal Ga Shale Development, Technolgy and Policy eee Figure 3 Major Natural Gas Transportation Corridors in the Conterminous United

‘earned Ou ‘Geog Dt Care's des fr Pong rebate et espn bt ess Say cero mop dou Po rie scr ear, bed on opens th Feder

Groundwater Resource Issues

As gus development in the Barnet Shale increased over the past dsead, water use also inersase

‘One study eximate tht water use for Barratt Shale eas development increased rom

angmoximately 700 aerefet (AF in 2000 vo mote than 7.000 AF in 2008.” Barnet Shale

‘development uses hath surface water and groudater reste, primarily for hy rauicaly Fracturing verial and horizontal wells Depending onthe well tye, fom 1.21035 lion agallons (Ito 11 AF of water may he consumed in hydraulically fracturing a gas wel OF the

‘pproximately 700 AF used in 2005, about 60% came from groundwater inthe Tiity ad

Woodbine aquifers north comtal Texas!" The deer Tinty apie underying 61 couse)

is much more extensive san the shallowes Woodbine aquifer (ndrlying 17 counties) The ste of Texas ab considers Teta mejor agufer compared 0 he minor Wendie”

‘The Teiniy Aquifer extends fom suth-sental Texas nsouteastem Okla in $50 mile ogg arlike hand (See Figure 4) ris an mmportam water soare for any commits, Trtevlsy nl im noth ental Texas where Barnett Shale evckpmet is mat intense

‘Groundwater use varies across the Barnett Shale developmen ara: for example rounds provides aprosimstely 88% ofthe total water supply in Cooke Cova but oly 1% for Dallas

‘County Extensive development ofthe Trinity Aga inthe Dalls-F Worth metwopoltan snes fad eas groursdater levels to dap ove $0 Tet in some seas, However, when thee patios Depa nceasing after the 197%, loa commmuitesshatdoned many publi sippy tells infor of surface water suppl This resale in a ocovery of groundwater levee ta sme

‘extent " For many curl acas, ower, graundwater from te Trinky gue rma the sole tvater source The Woodbine Aquifer, which is stallover than the Test offers another

sroardwater supply forthe reson The hnves ofits thre water Dearing layets ys he most water Toagh the Wowubine i minor agit, t xd he locally myportant ts Bart Shale cdetchptem giNen its prin

1096, hippies gota Rfid + ay of te Uno Ste, Oban, Te: HA TOD

a Att ad le Hpi, Maer

‘Conprasiona Rewer Broke

Unconentiona Ga Shales Development, Technolgy and Policy ues Figure 4 Aquifers in the Bend Arch-Fort Worth Basin Area

Notes: Gres cc ren reper th sala "or a" where mos fhe Barat She Secopmon ter ace

‘Congressional Roand Sue TT

A say hac modeled groundwater sein the atea conclu that aut 3% ofthe use was

‘ccocited wih the Bart Shales development in 2005," Dspeniing onthe pase of ee evchipinet, water use ich is esentl to hyeuaic fracturing) could sy wk

‘Scconing to the study low nur! gas prices Would slo iterest in devslopasem art thos slighty deteasegrumvater uss by 2025, High naturales gros could stile asserted

‘leselepe al hs increase stondweter dem for evelopment to att HON 0 25,08 [AP by 2025 fom Mỹ n 2005 1ø 7% lo lân hy 2028,

Increasing shale development coud compete with oer users fo he Same grounder

sours, particulary stra teas where grouswater isa sigaiiea Fastin of ater sup, Ieicunvensin ow urban teas may fet to gondvatr wl dling in ppt of shale

“developmen tha is, fr hydraulic Factorga), even touch proinwater comprises a smaller Faction of the water supply onipad some me tra ates The saadelng stay pained ạt

sẽ ve ha the Trin and Wovdbine ages unetie only the easter portion of the Barnet Sate; no major or minor aquifers underisthe western portions.” Development of western Potions acs the pss of rasperting rounder pumped forthe rity an

‘Woodbine agers inthe cas wo the western pono the Bart Shale, whic col ese

<stimates af potential prourdvater use above those preset ine nel rst

Marcellus Shale Formation

“The Marcellas Shales sedimeniary rock formstion deposit over 380 milion years ago ding the mie-Devonian period on the goulogie imescle- Geologie stata deere inthe

Appalachian basin ding this prio at key to proxluce more gs than i Regional oil

[ordustion is scott with Pennsylvanian age stata (of he ftt Carboniferous pti, Most

‘this lack organic rch sale es honcath nach of West Vieina, western and sorhsastern Pennsylvania, soutien New York, caster Ohio and pans of Vitgnia ond Marvland (sce Figure 5) lec amestiated 95,001 sre nes im arcl ext aa ranges fom 000 fst 08.50 Tet

in dept The shales non-aniform ticknoss varies ram 30 fos 250 ost s hư the isopaci map of Figure 5.” Sone reports indies ha sale's hicks maybe asic 36 0) Fest in ples, weve, As shown ih Figure 6 the Mares pags in depth te fue noth it oes the cos Seton

Unconentiona Ga Shale Development, Technolgy an Policy sues Figure 5 Marcellus Shale Formation Thickness

Source: US Gesegal Suny, Annet f Under Nal Gas Rats A Doin Bak as,

‘Aplin Ba, Ease USA, Oper Repo 200168 205,

Figure 6 Devonian Shale Cross Section

Souret: Compa rom USGS Open le Report 20-1268, 2005

Note: Cot scion Fo Als ta New York Vere see gpd

“Congressional Recah ere

Natural Gas Resource Potential

The USCS indicates hat the Marectos Shale may haves mean undiscoverel nturl gas resource petra of nearly 2 of Considering the total extent of Devonian Ohisbasin shales hi

lacudethe Mareelu formation, am estate 12 te may be preset oath not al of my

he sconomicaly recoverable (See Figure 7.) The USGS estate, however, considerably lover than a 2008 “conservative” estimate of S16 taf mae by gesseience professors Terry Engeldr Pennsylvania State Univesity ae Gary Lash State University of New York) The too prtessors hee tha that end bea st $0 eto es ehnealyrecaerale Fo the

‘Marvels Shale."

‘Typically thicker shales wih greatroegaie mates yield reps, and hus are mee

economically desirable to price Sale im aorthcast Pennsylvania and southeast Now York is

‘thse characteris an produces dry natural gas Shale in western Pennsylvania apd New York presses a water gs th contains proce lptỏc

Stat assumes that cach well dein the Marcellus may have an average estimated

is covery (EUR) of 8.1 be The EUR per well wil depend on te length of he

hosizontal wll dil the umber of racism the well ata he geaity ofthe ale

Sail yo assomes ht cach horizontal sell woud msisre 30 Fs net ith

oônhic Iacutes iMertaE in ach well An average well mit pnbce for pads of 4

stale Pay’ Vast ae hing Sua Apa” by Tay Engel Gay Lash sro

20 pd ate conte Noms And MaiNcr Dewan Seen

“Conprssiona Rewer Sree

LUnconentional Ga Shale Development, Tehnalogy and Policy eset Figure 7 Devonian Shale Undiscovered Resource Potential

tm

Source: USGS Open Fie Rapor 200.1268

Notes: NGL: nar ih ide btn al ropa

Northeast Regional Natural Gas Supply and Demand,

In 2007, the northeast region consumed roughly tet of natal gs New Yor le the region in

‘onsumpion with oer I-19 tf The United States 36a whole consumed mors than 23 tf.” The region prodced roughly S80 ef of natural gas fom some 113,000 operating pas Wel

Pennsylvania and West Virginia combined made up nearly 89% of the production with New

‘York and Virginia making up the balance In summary the region consumes about seven times as

‘much natural ga sit cutely produces The S0-ef of gs, ested by Engelder and Lash as

gi coe su en

Repth HA ae 2047.64 on eb pes aeons det

‘Currently, 20 imerstate natural gas tansnisson pipelines serve the noneast region ofthe United

te (se Figure 8)" The pipeline system delivers nara ua o several intrastate natal gts Tel and atleast 0 local isiibution companies im the region In addition wo the satral gas Psivce inthe region, several fon-stapce natural gas tarsission pipettes supply therepion Feo he southeast to Vieni a West Visa, al fom he Midwest no West Virion aa Penylvani, Cain imports come ito the resion prepay though New York, Mie, aa [New Hampsite Luete natural gas (LNG) supp als ene Ue region Hough impor terminals stein Massactusets, Maryland snd New Bronssick, Cana,

“The natural yas pre fr the eastern postion ofthe Marcellus Shales ot high eno

“quality that rots HH ao tre for insti at transmission pins A 3

ansssion pipsine already serves the northeast United Stats, The Milena) Piptie projet insoutheen New York could accommodate any increased shale pas production fom New York and pans of Penosivania serve the natural gas nee ofthe repo However the ez in

‘West Virginia presents an cbstacte 6 developing atonal pipeline capacity and ther support infrasimcire Gas pohiers would ao have to coasinct a extensive network of hen Pineties to bing the ps oa ofthe wel el,

LUnconentional Gas Shaler Development, Technolgy and Policy eee Figure 8, Northeast Region Natural Gas Pipeline Network:

Source ho Idophodo Adnkiersdee He Đi Ga, Nl Gt Don, Gt Troan

Notes: cues Cones, Debware Msn, Min New Hampi New ray NewYork

Femi Rhode Wd ng sd Wen Weg

Groundwater Resource Issues

‘The US Goologial Survey identities three principal hydrogeological envonments overlying the Marcellus Shale: (1) glical sand and gravel aquifers in New York porthera Penns vans

nb northeastera Ohio, 2 valley-and-sidgeearbonate rock and other aquifers in Pennsylvania and eastern West Virgina, and (3) Mississippian aifers in northern Pennsylvania and

northeastern Ohi These aquifer systems are important supplies of fresh wate for comma,

‘specially in more rural arcs, although in general most residents ofthese tates obtain their

‘inking Water from surface water sources Typically dese aquifers are much close tothe

“round surface than the Marellis Shale, which ean be haus of fet deep The groundwater Wells in these states may reach only several hundred feet n danh

‘The layers of rocks separating mos fresh water aquifers fom the Marcellas Shale are typically siltstones an shales lyered with minor sandstones and limestone Sistones and shales zenerally

ct sharin o Mud low These intervening layers of oeks ean be several thousand fet thick inthe eastern and noaern portions ofthe atea where the Marellas Shales deepest On the

‘western a sche portions ofthe area, the Marcelvs Shale is shallower, as separated bya thinner package of silstones an shales

‘Many ofthe surficial san and gravel aguifers frm valleyfill deposits, in lowelying tess or stream valleys, andar echargod by presipaton tht rans ff sarounding es permeable pleas.” AS set, they would be particularly suscep to kaky surface impoundments oF

‘ree surface spoil bscouse of the eaively shor stance univ tie roth lard Stirface othe tp othe water able, New York for example, hss dem se unconsolidated Sandal pravelaguifes “primary” or "principal aquifers, hich are highly productive ard presently uses siniicat source of wate, or area ptersalyabursa Wate upp

“The EPA defines an agife hat suppis at east 8 of te drinking water consume in the ren verging the auf as “soe oF pnp sure aie” (eFerted oor eanvenienee, a sole Soure aifers}” Those who depend onthe afer or drinking waterway hase to alterative

“inking Water source (physically, legally or acoaonically) The EPA fas designated a ess out Sole source aguters in Now York (EPA Region Mf) andre it PennsyWaaia Region Meh

‘overlie the Marcellus Shale (See Figure 9) ts uncertain whether these ancas would Be urges Tor Marcellas Shale develop

>How Tega Mase A er “Seca Suney Grn Was A of the Un Ses" A 738

* SecNew Vik Sue: Deano nsonmanal Comertion Pray &

“Conprasiona Rewer Broke

LUnconentional Gas Shaler Development, Technolgy and Policy eee Figure 9 Sole Source Aquifers in the Appalachian—Northeast Region

Drilling and Development Technology

In their carly stages of development, conventional petroleum reservoirs depend on the pressure of thể ga cạp and oi-tssolved as to ite ll to the surface (ue, gts drive), Water trapping the paroleum from below ao exerts an upward hydraulic pressure (water-dive Petroleum

reserits priced hy the presse of thet nara gs and water drives are this termed

“eonventional drive” Asa esevot'sprodetion declines iting Turher petroleum tothe surface requires pomping-—eiving ris tothe term “artificial Ki” Inthe late 1940s, dillngcompasies hogan indueing hydraulic pressure in wells fracture the producing formation This simulated further prouction by effectively increasing 4 well’ contact witha formation, Advances in licctional dling technology now enable wells to deviate fom arly verte to extend

hoeizomtally mo the reservoir formation, which increases the well’s contact withthe eservoir Directional dilling technology aso enables dling a numberof wells fom a single wel pad thus cui costs while reducing environmental disturbance Combining hydraulic racaring

th dieforaldiling ha opened up production of ihr (ess permeable) petroleum a

rar gas reservoir and in partivuls unconventional gos sales ike the Marvels

dling parculrl with the development of the cone rotary bức"? Tác matod, tế name liplies, ses a weghte tating itt penetrate the sels Figuee 10)

Ths hey tartar i's sped is he elie ease of aking new sections of dil piper ill string) while he dele comtinges craig Cizcating it line mà) đoạn trough the

‘er ofthe hollows dil ipe an up dhs the wl! Bre Hs the diluting to te suc

“Modern dil is sted with indus dana sives therm an abrasive property grind through any sock type Hover, from time to ime the el sting est he femove a poses teemad “wepping”) 2 replace the dled dil it

“To function propery ling lacs muyt ube the dil bt kop the Wel bone fom

solliming, and femive cuttings The wilt ofthe mi column prevents 2 "bho cut” fon

‘ceurting when encoudeting high-presae servo i Diets has the mad = compton

‘ona bentonite cay, a "xoknpc” material ha old when san Mai when

“isurbed Ths essential theological property Keeps the il etingssisperad inthe ma The rods chemise ant density mast he eoretully monitored and adjusted a he ailing deepens tor example, ang baru compound increases mad density "Mia pil” excavate tdjacene

to tho dil ig provide a reservoir for mixing and boli the mad The wad pis ako serve as Sctlng pons forth cutis, A the completion of ling, the md may be elo at anor tiling operation, bur the carting il eesposed fin the it Several environmental concerns

‘ering stem fom the thavardus) compotion of the ling mud and cutings ad the Petra ord pts overflowing and contaminating srface wate

Unconeationa Gas Shales Deselopment,Techaslgy and Pale ees Figure 10, Rotary Drilling Rig

“The mos recent advance indie the abit et the il bit beyond the eon

inmaditly henath the dil Da directional dling involved pacing a see! wedge down, hole (shipsock) dat deleted se dil zwar he esved target, ul lacked eon nd

‘onsuned time Advances sch x soeraledownbole dil mars thal operated on the yale Prssuncof the cnculating dling mul offered improved cretion contol However to change {ing direction the operator bad to Dall dil string rotation in such a poston ita end ithe moter pointed in the cretion ofthe new tractor (refered to as the sliding mde) Newer rotary steerable systems nro nthe 15) linn the net lide a stra down hole motor" The newer tole dil đirseionaly ửjleconiaotsly milel am the sueiee By the deling Hig, This enaens ch ote copes, an this sce, dling joo

‘Continoods rotation ao leds ta higher fates of peetacon al feusr Kids 0f he di tảng stoking (See Figure 11.)

“Conpessiona Rewer Sree CC”

Directional dling offers anther significant advantage in developing gas shales, Inthe ese of

‘hin orincine shale formations, along horizontal well increases the length ofthe wellbore in the gas-bearing formation and therefore increases the surface are for gas to low int the Wel However the increased well surface (length) is fen insufficient without some means of

artificially stimulating fw In some sandstone and carbonate formations, injecting dilate aid issolves the natural erent that bids snd grains thus inereasing permeability night

formations like shale inducing racure can increase Now by orders of magni, However, hfe stinailaton Tor that matter prodvetion can take lace, the well mast be completed ad ease

Figure 11 Directional Drilling

‘erable Downhole Motor vi Rotary Sterble System

Source: hag mde by CRS

‘Well Construction and Casing

‘Commercial gs and ol and municipal wate-supply wells have in common a series of

telescoping sto! well asings that prevent wellbore collapse and water infiltration while dling

‘The casing also conduct the priced reservoir Hid othe surface (sce Figure 12) A propy designed and cemented casing also prevents resevoit Nid (ga oo from inHitntingthe

‘overlying groundwater aquifers,

Daring the frst phase of eiling, termed “sping: shallow casing installed underneath the

“ling platform serves to enforce the ground srface Dailling continues to the bottom of the ater ible or the potable apie at which point the dil string is “tipps” out (removed) in

‘order 6 lower a second easing sting, which is cemented in and phgged atte bottom Drillers tse special oi-well cement that expands whe it st oil he void between he easing and the

—

“Congressional Resende

Unconentiona Ga Shales Development, Technolgy at Policy sues Surface casing and easing to the bottom of the water table prevents water from Roding the well

‘wile also protctng the groundvatr from contamination by drilling Ms and reservoir Mui, (The iil drilling stages may use compressed ai in place of dling Mui o avoid

comtaninating the potable aguifer.)Driling and casing then continue tothe “py zone"—the formation that prices gas ro, The numer and length ofthe easing, however, depends on the depth and the properties ofthe gelogie sat

Figure 12 Hypothetical Well Casing

Note: No Sale fcr completing the well othe target depth and cmenting-in he final easing, the ding operator may hire an ol-wel service company run a "cement evaluation log” An electric probe lowered int the wel, measures the cement thicknes, The cement evaluation log provides the critical confirmation that the cement will funtion as dcsigned—preventing Well hide fom bypassing outside de easing and infiltrating overlying formations

problems, Pennsylvania instituting regulations tht require a minimum 2,000-oot setback between anew ga-well and an existing water wel

Hydraulic Fracturing,

Despite some shales abundant nats content they donot produce gas fey Ezonomie

production depends on some means of anf stimulating shale o liberate gas In the late 1940s, Texas oil ils responded to Mids pumped down wells undct pressures high enough 0

‘actu stint the producing formation, Hyde rate scnwlaton teat meni have een dap o tight gs formations such the Barnet Shak in Texas, and more revel thề

Marels Shule

“Typical “rac” eaten or Fae obs (4s commonly referred o) ae elaively lage operations

‘omar some deiling operations Th old stvie company contacted fo the work my lake a mech o stag the jo an «convoy of rics to deliver the ssuipment an mils ced (sce Figure 13

Aconspany involved in developing Texas us shale offered the following description ofa fete

jo

Shae ga wells va dil ty adit wept nal ney ese,

The rock around De wllboee ost he hyaline fe the wll aa peo

‘Senifcun emounts fsa, Pacring invokes tating aioe of thew eons

“dục tien pumping ds ropa asf an the tal se a bd the

(rks ops) do heehee polos the caning snout the se

‘he pnp id eer rsx opto poh pera ae asap 0)

‘Schauer (ose water tse i) and ppp Nebopes Lome acta Tis St como pond stale shales sa sles with lo eer Pees

hepa sh conledabacewlaiacresal gp