Control Of Longwall Gob Gas With Cross- Measure Boreholes .
Bureau of Mines Report of Investigations/l983Control of Longwall Gob GasWith Cross- Measure Boreholes(Upper Kittanning Coalbed)By A. A. Campoli, J. Cervik, and S. J. SchatzelUNITED STATES DEPARTMENT OF THE INTERIOR
Report of Investigations 8841Control of Longwall Gob GasWith Cross- Measure Boreholes(Upper Kittanning Coalbed)By A. A. Campoli, J. Cervik, and S. J. SchatzelUNITED STATES DEPARTMENT OF THE INTERIORWilliam P. Clark, SecretaryBUREAU OF MINESRobert C. Horton, Director
Library of Congress Cataloging in Publication Data:1Campoli, A. A. (Alan A*)Control of l o n g w a l l g o b g a s with c r o s s - m e a s u r e b o r e h o l e s (UpperKittanning Coalbed).( R e p o r t of i n v e s t i g a t i o n sreau of Mines ; 8 8 4 1 )Bibliography:/United S t a t e s D e p a r t m e n t of Interior, Bu-p. 17.Supt. of Docs. no.:I 28.23:8841.1. Fire-damp.2. C o a l m i n e s a n d mining-Safety m e a s u r e s . 3.Mine ventilation. 4. Boring. I. C e r v i k , J o s e p h . 11. S c h a t z e l , Steven J. 111. Title. IV. Series: R e p o r t of i n v e s t i g a t i o n s ( U n i t e d S t a t e s .Bureau of Mines) ;8841.TN23.U43 [TN305] 622s [622',8]83-600321e
sStudy a r e a r o s s - m e a s u r eb o r e h o l e system d e s i g nID r i l l i n g equipment and p r o c e d u r e siPiping s y s t e m and flow measurement p r o c e d u r e sSurface venting f a c i l i t yProduction d a t aGob g a s p r o d u c t i o nWater p r o d u c t i o nP a r t i a l vacuum a p p l i e d t o c r o s s - m e a s u r e b o r e h o l e sE f f e c t s of t h e c r o s s - m e a s u r e s y s t e mSummary and c o n c l u s i o n sReferences.ILLUSTRATIONS.G e n e r a l i z e d s t r a t i g r a p h i c column of P e n n s y l v a n i a n s y s t e mS t r a t i g r a p h i c column above Upper K i t t a n n i n g CoalbedBethlehem Mines Corp.'s Cambria 33 Mine (Upper K i t t a n n i n g Coalbed)Longwall t e s t p a n e lSchematic of c r o s s - m e a s u r e b o r e h o l e d e s i g n p a r a m e t e r sElectrohydraulic d r i l l i n g unitHydraulic d r i l l c o n t r o l u n i tExpandable mechanical p a c k e rS t u f f i n g boxSynthetic diamond w a f e r b i t sETA d r i l l r o d b e i n g added t o d r i l l s t r i n gP l a s t i c standpipe with socketsC r o s s - m e a s u r e b o r e h o l e equipmentSurface venting f a c i l i t yMethane flow r a t e sGob g a s f l o w r a t e sHole l i f e v e r s u s i n c l i n a t i o n a n g l eHole l i f e v e r s u s p e n e t r a t i o n i n t o gobCross-measure. l o n g w a l l r e t u r n . and t o t a l methane f l o w r a t e sE f f e c t of t h e c r o s s - m e a s u r e s y s t e m on t h e mine v e n t i l a t i o n s y s t e m.TABLE.1P r o d u c t i o n h i s t o r y of c r o s s - m e a s u r e b o r e h o l e s.
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORTcentimeterkWkilowattdegreeLliterfoot /minl i t e r per minutecubic f o o t p e r minutemmetergallonmmmillimeterg a l l o n p e r minutem3/sc u b i c m e t e r p e r secondhourPetpercenthorsepowerradradianinchVACvolt alternating currentkilopascal
CONTROL OF LONGWALL GOB GAS WITH CROSS-MEASURE BOREHOLES(UPPER KITTANNING COALBED)By A. A.Carnpoli,' J.Cervik,andS. J.SchatzelABSTRACTThe cross-measure b o r e h o l e t e c h n i q u e i s b e i n g s t u d i e d by t h e Bureau ofMines a s a n a l t e r n a t i v e t o t h e u s e of s u r f a c e gob b o r e h o l e s a s a meanso f c o n t r o l l i n g methane i n gobs d u r i n g l o n g w a l l mining.Small-diameterh o l e s a r e d r i l l e d from underground l o c a t i o n s i n t o s t r a t a o v e r l y i n g t h eWhen t h e roof s t r a t a a r e f r a c t u r e d by t h e mining operamined c o a l b e d .t i o n , a p a r t i a l vacuum a p p l i e d t o t h e b o r e h o l e s draws t h e methane o u t oft h e f r a c t u r e d s t r a t a and p r e v e n t s i t from e n t e r i n g t h e mine v e n t i l a t i o nsystem.T e s t s i n t h e Upper K i t t a n n i n g Coalbed showed t h a t 50 p c t of t h e metha n e produced by t h e l o n g w a l l mining o p e r a t i o n was c a p t u r e d by t h e c r o s s measure b o r e h o l e s .Borehole i n c l i n a t i o n and p e n e t r a t i o n i n t o t h e goba r e two i m p o r t a n t b o r e h o l e p a r a m e t e r s t h a t a f f e c t t h e performance of t h ecross-measure b o r e h o l e system.'Mining e n g i n e e r .'-s u p e r v i s o r y g e o p h y s i c i s t .P i t t s b u r g h R e s e a r c h C e n t e r , Bureau o f M i n e s , P i t t s b u r g h , PA.
INTRODUCTIONMethane produced by l o n g w a l l o p e r a t i o n si n t h e United S t a t e s i s c o n t r o l l e d byd i l u t i o n w i t h v e n t i l a t i o n a i r and by s u r f a c e gob boreholes.S u r f a c e gob boreh o l e s cannot always be d r i l l e d becausemining may be under populated a r e a s ,topography may be t o o s e v e r e , o r a c c e s st o p r i v a t e p r o p e r t y may be denied.Cons e q u e n t l y , a n a l t e r n a t i v e method of cont r o l l i n g gob g a s i s needed t h a t i s independent of t h e mine v e n t i l a t i o n systemand s u r f a c e right-of-way problems.The s i n g l e - e n t r yl o n g w a l l i s t h e predominant mining system i n Europe whereb o t h r e t r e a t i n g and advancing l o n g w a l l sa r e used.However, t h e p r o p o r t i o n offacesutilizingadvancing t e c h n i q u e sdominates, w i t h 8 2 p c t i n Great B r i t a i n(2)4and 75 p c t i n West Germany (3).Post-World War I1 mechanization and mini n g of d e e p e r and g a s s i e r coalbeds f o r c e dt h e a p p l i c a t i o n of gob d r a i n a g e systemson European longwalls.The most commonlyused method of c o n t r o l l i n g gob g a s d u r i n gmining i n Europe i s t h e c r o s s - m e a s u r eI t i s indeborehole techniquependent of t h e mine v e n t i l a t i o n systemand s u r f a c e right-of-way problems.Thisr e p o r t d e s c r i b e s j o i n t e f f o r t s by t h e(1).4 n d e r l i n e dnumbers i n p a r e n t h e s e s r e f e r t o i t e m s i n t h e l i s t of r e f e r e n c e s a tt h e end of t h i s r e p o r t .1Upper Freeport Coalbed (E)Upper Freeport LimestoneBolivar fire clayI !,Butler SandstoneFQ,Lower Freeport Coal bed (DlLower Freeport LimestoneLower- FreeportLICoalbedtFree port Sandstone*W0Upper Kittanning Coalbed (c')Johnstown LimestoneUpper Worthington Sandstoneccn'-0v-Upper,FreeportCoalbedZ2cn-2Ea 'FnEL9cnMiddle Kittanning coal group (C).-CCC0. YLower Worthington SandstoneLower Kittanning "rider"coalbed ( B )Upper,CoalbedLower Kittanning Coalbed ( 6)FIGURE1.- Generalized stratigraphic columnof Pennsylvanian system. L e t t e r s i n parenthesesare l o c a l seam designations.Kit tanningBone coalCoalClayFIGURE 2.-ShaleI:SandstoneF;i7-1 LimestoneStratigraphic column above UpperKittanning Coalbed.
Bureau and Bethlehem Mines Corp. t o a d a p tt h e cross-measureboreholetechniqueof gob g a s c o n t r o l t o m u l t i p l e - e n t r yr e t r e a t i n g l o n g w a l l s i n t h e Upper K i t t a n n i n g Coalbed.ACKNOWLEDGMENTSThe a u t h o r s thank t h e f o l l o w i n g pers o n n e l of Bethlehem Mines Corp.'s CambriaDivision f o rtheircooperationanda s s i s t a n c e i n t h e s t u d y a t t h e Cambria 33Mine, Ebensburg, PA: E. J. Korber, manBurns,g e n e r a l superager;F. A.i n t e n d e n t ; D. Weaver, mining e n g i n e e r ;B i l l Radebaugh, mine foreman; and PaulRusnak, g e n e r a l a s s i s t a n t .The cooperat i o n of t h e C e n t r a l Mining I n s t i t u t e ,Katowice, Poland, i n d e s i g n i n g t h e c r o s s measure boreholesystemisgreatlyappreciated.STUDY AREAThe s t u d y a r e a was l o c a t e d i n Pennsylv a n i a n age s t r a t a of t h e Allegheny Group,s p e c i f i c a l l y t h e K i t t a n n i n g and F r e e p o r tFormations ( f i g . 1 ) (k, p. 6 ) . The UpperK i t t a n n i n g Coalbed, l o c a l l y c a l l e d t h eC-prime( C ' ) seam, v a r i e s from 29 t o 45i n (74 t o 114 cm) i n h e i g h t o v e r t h e/\/"s t u d y a r e a (6, pp. 5-7).A detaileds t r a t i g r a p h i c column wasproduced byanalyzing d r i l l cuttingsfrom c r o s s measure b o r e h o l e s ( f i g . 2).It showst h r e e coalbeds which a r e known s o u r c e sf o r methane.These coalbeds a r e l o c a t e d40,50, and 90 f t (12,15, and 27 m)above t h e roof of t h e Upper K i t t a n n i n gCoalbed.The t e s t was conducted on a r e t r e a t i n gl o n g w a l l i n Bethlehem Mines Corp.'s Camb r i a 33 Mine ( f i g . 3).An e n l a r g e d viewof t h e t e s t p a n e l i s shown i n f i g u r e 4.The underground p i p e l i n e i s l o c a t e d i nt h e c e n t e r e n t r y of t h e t h r e e - e n t r y r e t u r n a i r gateroad.A l l cross-measureb o r e h o l e s were d r i l l e d from t h e c e n t e re n t r y , which was s u p p o r t e d by a l i n e ofc r i b s and remained open and p a s s a b l ea f t e r t h e p a n e l s on both s i d e s wereremoved.i'Eroluor8on0Ol"tSurfoce boreholeC. J-FIGURE 3.Bethlehem Mines C o r p . ' Cambria33 Mine (Upper Kittanning Coalbed).FIGURE 4.- Longwall test panel.
CROSS-MEASURE BOREHOLE SYSTEM DESIGNThe d e s i g n of t h e cross-measure borehol-es was based on European i n f o r m a t i o nand knowledge g a i n e d i n a p r i o r Bureau ofFigure 5Mines s t u d y ( 7 , pp. 2 , 4 , 13).borehole parameters,shows t h e f T n a lwhich were d e t e r m i n e d through i n - h o l esurveys.The e n d p o i n t s oft h e cross-measureb o r e h o l e s were s p a c e d 250f t ( 7 6 m)apart.A l l b o r e h o l e s were d r i l l e d o v e r asupport p i l l a r t o protect t h e borehole*Cross-measure borehole numberA-BD i -C.1. M a i n t a i n t h e h e i g h t of t h e b o r e h o l eo v e r t h e f a r end of t h e s u p p o r t p i l l a r a tl e a s t e i g h t times t h e coalbed t h i c k n e s sE s t i m a t e s of t h e h e i g h t of(fig. 5, E).t h e r u b b l i z e d zone i n t h e gob r a n g e f r o m4 t o 8 times coalbed thickness.I n c l i n a t i o n , degreesH o r i z o n t a l angle, degreesPlan viewHole l e n g t h , f e e tT e r nnalih e i g h t o f hole, f e e tHeight o f holedtend o f supported l e n g t h , f e e tF-P e n e t r a t i o n over 1ongwall panel, f e e tG-Distance from s t a r t o f panel t o endpoint of hole, f e e tHwhen t h e l o n g w a l l f a c e p a s s e d t h e c o l Borehole l e n g t h , i n c l i n a t i o n , andlar.horizontal directionwerechosen t oaccomplish t h e following:Distance froin endpoint t o o r i g i n of hole, f e e tFIGURE 5.-Elevation viewSchematic of cross-measure borehole design parameters.
2.Terminate t h e b o r e h o l e a b o u t 100 f tPol(30.5 m) i n t o t h e gob ( f i g . 5 , F ) .i s h s t u d i e s show h i g h e r methane concent r a t i o n s i n t h e gob on t h e r e t h r n s i d et h a n t h e i n t a k e s i d e because of t h ep r e s s u r e d i f f e r e n t i a l s of t h e mine's vent i l a t i o n system ( 5 ) .-4. Angle t h e b o r e h o l e a t l e a s t 45'(0.79 r a d ) t o t h e a x i s of t h e l o n g w a l l( f i g . 5 , 2).G e n e r a l l y , g a s p r o d u c t i o n begins whent h e f a c e i s 75 t o 100 f t (22.9 t o 30.5 m)beyond t h e end of t h e borehole but b e f o r ei t passes the collar.3.I n t e r c e p t a l l coalbeds a t l e a s t100 f t (30.5 m) above t h e mined coalbed( f i g . 5 , 2).DRILLING EQUIPMENT AND PROCEDURESAn e l e c t r o h y d r a u l i c d r i l l mounted on 3h y d r a u l i c j a c k s was used t o d r i l l t h e 12Bitcross-measure b o r e h o l e s ( f i g .6).t h r u s t and r o t a t i o n a l speed were a d j u s t e da t t h e c e n t r a l u n i t , which was l o c a t e d 10t o 1 5 f t (3.0 t o 4.6 m) from t h e d r i l lFIGURE 6.-u n i t ( f i g . 7).The skid-mountedpowerpack was l o c a t e d i n a f r e s h a i r e n t r yduring d r i l l i n g .It c o n s i s t s of a 20hp (14.9-kW),460-VAC, three-phase e l e c t r i c motor, a h y d r a u l i c pump, and a 35g a l (132-L)hydraulic reservoir.TheE l e t r o h d r a u l drillingicunit.
FIGURE 7.hydraulic f l u i d is a fire-resistantw a t e r emulsion f l u i d .-Hydraulic d r i l l control unit.60/40The f i r s t 26 f t (7.9 m) of each bore(102-mm)h o l e was d r i l l e d w i t h a 4-indiamond c o r e b i t , and t h e c o r e s were r e moved i n 30-in (76.2-cm) s e c t i o n s .Theremainder of t h e h o l e was d r i l l e d w i t h a1.9-in(48-mm)bit.Because abnormalmethane flows could be encountered d u r i n gd r i l l i n g of t h e 1.9-in (48-mm)hole, a l ld r i l l i n g was conducted through a s t u f f i n gbox a t t a c h e d t o a 4-in(1021nm) expanda b l e mechanical packer ( f i g . 8 ) .Returnw a t e r and d r i l l c u t t i n g s were t r a n s p o r t e dt o a w e l l - v e n t i l a t e d a r e a 30 f t (9.1 m)downstream from t h e d r i l l s i t e through ahose connected t o t h e mechanical packer(fig. 9).The packer, s t u f f i n g box, andv a l v e a t t h e end of t h e d r a i n a g e hose
FIGURE 8.- Expandable mechanical packer.FIGURE 9.provided t h e means t o s h u t - i nt h e boreh o l e i f abnormal methaneflows weree n c o u n t e r e d d u r i n g d r i l l i n g . However, noabnormal flows o c c u r r e d d u r i n g t h e d r i l l i n g of any of t h e h o l e s on t h e t e s tpanel.- Stuffing box.A s y n t h e t i c diamond wafer b i t[1.9 i n(48 mm)] was used t o d r i l l t h e c r o s s measure b o r e h o l e s ( f i g . 10). P e n e t r a t i o nr a t e through t h e s a n d s t o n e s and s h a l e saveraged 70 f t (21.3 m) p e r s h i f t , andb i t l i f e was e x c e p t i o n a l .Only one b i t
FIGURE 10.- Synthetic diamond wafer bits.was used t o d r i l l a l l c r o s s - m e a s u r e boreh o l e s on t h e t e s t panel.F i g u r e 10 comp a r e s a new b i t (A) t o one t h a t hadd r i l l e d o v e r 3,100 f t (945 m) of rock(B). The diamond w a f e r s a r e chipped andworn t o t h e p o i n t where t h e m a t r i x hadbeen rubbing on t h e rock s u r f a c e d u r i n gdrilling.The worn b i t (B) can be s a l vaged by removing t h e diamoxd w a f e r s andr o t a t i n g them about 180" (3.1 r a d ) .Thec o s t t o s a l v a g e t h e b i t i s about h a l f t h ec o s t of a new b i t .The d r i l l u n i t was l i m i t e d t o a l e n g t hof about 54 i n (137 cm) ( f i g . 6) becausecoalbed h e i g h t i s about 45 i n (114 cm)and h o l e s w e r e i n c l i n e d upward 23" t o 33"D r i l l rods a r e 1.6(0.40 t o 0.58 r a d ) .i n ( 4 1 mm) i n d i a m e t e r and 15 i n (381 mm)A, New; B , worn.l o n g ( f i g . l l ) , which r e q u i r e d f r e q u e n tinterruptions i n drilling t o insert d r i l lrods.The rods were screwed i n t o oneanother with a s p e c i a lcoarse tapert h r e a d (ETA) f o r r a p i d connection anddismantling.No c e n t r a l i z e r s were usedd u r i n g d r i l l i n g because of t h e s m a l l d i f f e r e n c e i n d i a m e t e r between t h e d r i l lr o d s and b i t .Downhole s u r v e y s showedl i t t l e v a r i a t i o n i n borehole t r a j e c t o r y .P l a s t i c s t a n d p i p e s were cemented i n t oe a c h cross-measure borehole a f t e r t h ecompletion of t h e d r i l l i n g phase.Thecementing phase i s i m p o r t a n t because i fn o t completed p r o p e r l y , mine a i r couldshort-circuitintot h e cross-measureb o r e h o l e , reducing i t s a b i l i t y t o drawmethane from t h e gob.
FIGURE 11.- ETA d r i l l rod b e i n g added to d r i l l string.
Two g r o u t i n g p r o c e d u r e s were t e s t e d t od e t e r m i n e t h e b e s t method of g r o u t i n g t h estandpipes.I n h o l e s 1 t h r o u g h 7, 9 , and10, 5 - f t ( 1 . 5 9 ) l e n g t h s of 2.25-in (57mm) d i a m e t e r p l a s t i c p i p e were j o i n e dwith sockets.T o t a l l e n g t h of s t a n d p i p ewas a b o u t 20 f t (6.1 m) ( f i g . 1 2 ) . S h o r t15-in (38-cm)p l u g s of cement were emp l a c e d e v e r y 30 i n ( 7 6 cm) a l o n g t h ep l a s t i c pipe.I f roof movements d u r i n gm i n i n g c a u s e a misalignment of t h e h o l e ,t h e p l a s t i c p i p e bends a t t h e s o c k e tj o i n t s and b e c a u s e t h e cement i s emplacedi n s h o r t p l u g s , c r a c k i n g would be minimal.In holes , ,and 12, 1.25-in(32-mm), 2.5-in (64-mm), and 2-in (51-mm)diameter p l a s t i cpipes, respectively,were g r o u t e d 18 f t (5.5 m) i n t o t h eholes.D r i l l i n g t h e h o l e and g r o u t i n gt h e p l a s t i c standpipe required about f i v e8-h s h i f t s by a t h r e e - p e r s o n crew.PIPING SYSTEM AND FLOW MEASUREMENT PROCEDURESAccess t o t h e s u r f a c e was p r o v i d e d by a688-f t ( 2 1 0 9 ) l o n g ,12-in(30.5-cm)diameter s u r f a c e borehole ( f i g . 4).Theb o r e h o l e was c a s e d w i t h 8-in (20.3-cm)steelp i p e and cementedthe entireA 6-in(15.2-cm)crushprooflength.p l a s t i c p i p e l i n e [ 4 , 7 5 0 f t ( 1 , 4 4 8 m)]connected t h e s u r f a c e borehole t o t h ecross-measure boreholes.Movement of a g a s through a p l a s t i cp i p e l i n e can c a u s e a s t a t i c c h a r g e b u i l d u p on t h e p i p e l i n e .A s t a t i c c h a r g e cani g n i t e e x p l o s i v e methane-airmixtures.To d i s s i p a t e t h e s t a t i c c h a r g e , t h e ent i r e p i p e l i n e was wrapped w i t h b a r e copp e r w i r e , which was a t t a c h e d t o coppergrounding rods.These r o d s were p l a c e di n 10-f t (3-m) h o l e s d r i l l e d i n t o t h eb o t t o m and packed w i t h c h a r c o a l .Theg r o u n d i n g r o d s were s p a c e d 500 f t (152 m)along the pipeline.The p i p e l i n e e n t r y a d j a c e n t t o t h e t e s tpanel ( f i g .4) s l o p e d a b o u t 1 p c t downward from h o l e 12 t o 1 ; a t t h e r i g h t a n g l e bend,the slope increased t o 3p c t downward toward t h e v e r t i c a l borehole.Water f l o w from t h e c r o s s - m e a s u r eb o r e h o l e s was d i s c h a r g e d d i r e c t l y i n t ot h e main p i p e l i n e ; a t t h e r i g h t - a n g l ebend,t h e w a t e r was c o l l e c t e d i n a 2-in(51-mrn)metal p i p e l i
borehole was 3.0 in Hg (10.1 kPa) and gob gas flow was 27 ft3/min (0.013 m3/s). At another hole, the partial vacuum was 0.9 in Hg (3.0 kPa) and gas flow was 107 ft3/min (0.050 m3/s). Gob permeability is the dominant factor affecting flow and partial vacuum at a cross-measure Pressure measurements with a U-tube
Prediction of Longwall Methane Emissions: An Evaluation of the Influence of Mining Practices on missions and Methane Control Syst ' *iJ, srnvrr@a U.S. DEPARTMENT OF HEALTH UMAN SERVICES Public Health Service Centers for D sease Control and Prevent on
floor dinting are executed in the tail gate of panel 121304 (Figures 2(d)–2(e)). In fact, surrounding rock instabilities presented in Figure 2 are attributed to the stress redistri-bution resulting from the longwall mining. us, mining-induced stress should be investigated for optimizin
The longwall shields were shipped to the Oak Grove Mine in October 2016 without yield valves and pressure gauges. Those devices were to be installed once the shields were in place underground. Each longwall shield is equipped with a pilot-operated check valve. The purpose of the check va
Gates Industrial Ilok Hose Couplings Brochure Subject: Conditions in a longwall mine play havoc with traditional staple-lock and super-staple-lock couplings. Operating pressures of 5,000 psi in the hydraulic hoses connecting the shields on your longwall miner put 60,000 ft-lbs of force against the fittings. Created Date: 20130529201335Z
mechanization. One of these methods, the underhand longwall cut-and-fill method (fig. lB), was chosen for testing at the Lucky Friday Mine, Mullan, ID (fig. 2). The experimental stope, dubbed the Lucky Friday underhand longwall (LFUL) stope (fig. 3), was tested under a coop erative agreement among the Bureau, Hecla Mining Co.
measure rocks over a longwall coal mine in SW Pennsylvania. This approach demonstrated that it could be used for prediction of elastic and shear moduli of coal-measure rocks with reasonable accuracy. 1. Introduction The properties of coal-measure rocks within the longwall overburden are important because of replacedtheir controlling effect on
Abstract: Natural gas compressibility factor (Z) is key factor in gas industry for natural gas production and transportation. This research presents a new natural gas compressibility factor correlation for Niger Delta gas fields. First, gas properties databank was developed from twenty-two (22) laboratory Gas PVT Reports from Niger Delta gas .
new university, 13 members of academic staff and 26 students were interviewed in the same way. The interviews at both institutions included the Directors of Quality Assurance Units and 'learning support' staff. One of our initial research objectives was to explore the contribution of ethnographicbased research to educational development in higher education. The short length of the project .
