well and well pump submersible pumpDesign.pptx

design of well based on AED and pump design

1. Her at Un i ve rsity En g i ne e ring Fac u lty W ater S u pp l y En g i ne e ring Tube Well & W ell Pump Design

2. Con s truct i on a n d Boring of Tube well T h e meth o ds of b o ring w e lls c a n be cla s sified into Drilled Well C a ble to o l m et h od of drilling is k n o w n as p e rc u s s ion drill i ng ( ha m m e ring a n d c utting) whi c h s uita b le for c utting c o n s oli d at e d ro c k D irect R o tary meth o d I t is s u itable for u n c o n s o lidated formation s u ch as s a n d , gra v el T h e m e th o d in v ol v es a c o n tinu o u s ly rotating h o llow bit thro u gh w h ich a m ixt u re of c lay a n d w at e r or m u d is forc e d. T h e bid c u t t in g s are c arried up in the h ole by r i s ing the m u d

3. Con s truct i on a n d Boring of Tube well T h e meth o ds of b o ring w e lls c a n be cla s sified into Dri v en w e lls J etted t u b e w ells dril l ed tube wells Driv e n Well w h ere the a s s e mbly is forced do w n the gro u nd to p e n e t r ate into the w a ter b e aring form a tion J e t t ed Well A h o le in the gro u nd is ma d e by t he cutting a c tion of a s t r e a m of w a ter w h ich is p u m p ed into the w e ll thro u gh a s m all pi p e di a m e ter.

4. Tube well Deep tu b e w e ll d e p th is a b o u t 7 to 300 m Yi e ld c an be a s h i gh a s 20 l/s Avera g e yield is 4 to 4 5 l/s Classif i ed i n to two cat e g o ri e s Cavity type (spher i cal fl o w) Screen type (rad i al fl o w)

5. Screen type tube well Stra i n e r tu b e w e ll Not reco m m e nd for fi n e sa n d

6. Slotted pipe with gravel p a ck Gravel p a ck is re q uir e d in fi n e a q u if e r • D 1 < . 2 5 mm

7. Well design features We l l c a si n g dia met e r Ca si n g mat e rials Well and ca si n g d ep t h We l l s c r e e n length a n d di a met e r We l l s c r e e n sl o t o p e n i n gs Aqu i fer a n d w e ll d eve l o pm ent a n d g r a v el pack mat e rial Collect i on and a nal y sis p ump te st and wate r q u a li t y d ata of Selec t i o n of w e l l p u mp

8. Sele c tion of a W ell Site

9. Well casing diameter

10. Casing material The pr e ferr e d casing m a ter i al is steel (ASTM A 5 3 Gra d e B o r ASTM A 139 Grade B). The PVC p i pe m u st be at le a st Sche d ule 8 or SDR 17 . PVC sha l l NOT be u sed f o r we l ls d e e p er t h an 80 m.

11. Well screens Mi n im u m t ot a l l e n g th of PVC s c re e ns sha l l b e f o ur ( 4 ) m e t e rs. M i n i m um tot a l le n gth of stai n less steel sc r e e ns shall be two ( 2 ) m e ters

12. Design the si z e of the s lot openings of a screen The s l ot o p e n i ngs d e p e n ds on t h e s iz e of the a q u i fer ma t e r i a l Over s iz e d slot will p ump fi ner mate r ial and will be d i ff i cu lt to o bta i n c l ear wat er Und ersiz ed s l ot will r esu lt in m ore h e ad l oss an d c o r r os i on The o ptimu m va l u e i s de t e r min e d by mat c h i ng the s i ze of the o p e n i n g a n d t he g r a i n s iz e distr i b u ti o n cu r ve In P ra c tic e i t ranges b etween 0.2 mm t o 5 mm

13. Design the si z e of the s lot openings of a screen Slo t o p e n i ng f o r a n on g r a v el p a ck we l l The o ptimu m s l ot si z e i s ch o se n a s the o n e which r eta i n 40% of the s an d . This may v a r y fro m a q u i fer to a n ot h er Slot op e n i ng for a g r a v el p ack well On the g r ain s i ze di str i bu t ion cu rv e a po i nt of 90 % s i ze is r eta i n e d i n d i cate the o p timu m s l ot si z e. The a c tu al siz e may be f i xe d within 80 % of the D 10 siz e of t h e gra v el pa c k

14. Filter pac k ing (gravel packing) is primari l y sand and gravel placed around the we l l screen t o stabi l ize the aquifer and provide a radius of high permeability around the screen. The we l l screen ape r tu r e size w i ll be selected so th a t be t ween 8 5 an d 10 perce n t of t he filter pack is larger than the screen openin g s The thickness of the filter pack wi l l range f r om a minimum of 75 mm to approxima t ely 20 mm

15. Filter pac k ing (gravel packing) Gr av el Pa c k d esi g n The g r a v el p a ck sh o uld be d e s i gn b e fo r e the d e si g n o f the s ize of the sl ots The g r a v el p a ck sh o uld be d e s i g n ed u si n g Pack Aqu i fer Rat i o ( P A ) P A ra t io = D 50 of the grave l / D 50 of the aq u if e r PA r a ti o n s h o u l d b e b etwe en 9 to as 1 2.5 fro C u ≤ 2 PA r at i on s h o u l d b e b etwe en 1 2 to as 1 5.5 fro C u ≥ 2 Howe v er Cu s h o u l d be k e pt is e q u al o r les s th a n 2.5

16. BENEFI TS Gr e a t er poro s i t y Higher h y dr a ulic cond u c t iv i t y Reduc e d dra wd o wn Higher y i eld Reduc e d en t ra nce v eloci t y Fas t er dev e lopment Eas i er gro u ting L o n g er well li f e Improved well r ehabili t a t ion Red u ce sand p u mping Filter pac k ing (gravel packing)

17. Screen length • L=Q/(AV ) L=length of scr e en Q=discharge A=effec t ive open area per unit length of screen length A pproximately ½ of the actual open area which can be obtained f r om screen m anufac t urers. V=ve l ocity above wh i ch a sand particle is t r anspor t ed

18. Screen length

19. Grouting and Seal i ng. Grout sho u ld exte n d from the surface to t h e t o p of t h e b e n t o n ite seal over l ying fil t er p ack o f the well The well casing a n d t he gr o ut seal sho u ld ext e nd fr o m t h e surf a ce to t h e d e pth n e ces s ary to pr e vent surface con t a m i n a t i o n via c h a n n e ls t h ro u gh soil a n d r o ck strata

20. Well Pumps Capac i ty of we l l Capac i ty of system S i ze of we l l Depth of water Type o f well Pow e r source Stan d by equipment Well drawdo w n Total dynamic head

21. Pump Capac i ty TDH=HS+ H D+HF+( V 2 / 2 g) H s =s uc t i o n l if t ; ve r tic al d i s t a nce fro m the wate rl i ne at dra wdown un der fu l l c ap a ci t y to the p u mp cent erl i n e , m HD=di s ch a r ge h e a d ; v e r tic al d i s t a nce f r om t he pu mp cent erl i ne to t h e pres s u r e l e v el of the d i s c h a r g e pi p e s y s tem, m HF=fri cti o n h e a d ; l o s s of h e a d o n pi p e l i nes a n d fi t ti n g s, m V 2 / 2 g= v e l o city h e a d ; h e a d n e c e s sary to mai n ta i n fl ow, m

22. Pump brake horsepower • P=(HQ)/ ( 102 *e) Wh e re: P=br e ak p o wer re q uir e d, kW H=t o t a l d yna m ic h e a d , m Q= v ol u me of wat e r dischar g e d , L/s e=Co m bi n ed e f ficie n cy of p u mp a n d m o tor, from m a n u fact u rer ’ s d a ta

23. Sample problem Site data Depth of well is 80 m Stat i c wate r t a ble is 1 4 m Draw d own is 1 m Screen open area = 12% Wat er demand ADD = 19 lit ( 5 g a l) Po p u l at i on = 3 8 person Peak f ac t or = 1. 8 Wa t er d e ma n d = 1. 8 x 19 x 38 = 1 29.96 m 3 /d ay Pump hours = 16 hr Req uire d fl o w = 1 29 .96 / 1 6 / 6 / 6 = 2. 2 5 L/s

24. Casing Diameter & Material Q= 135 lpm Casing Would E x ten d 3 m below the Pumping water level Mate r ial is P V C Sch . 80

25. Screen Length   So the screen length is 8 m

26. Well pump design Riser pipe based on maximum velocity Limit of 4 ft /sec (1.22 m/sec) V=Q/A  

27. “ Total Dynamic Hea d ” (TDH) TDH = Hs + Hd + H f + Hv Suction Head • Hs = 8 – 1 4 – 3 (pump location) – 1 (drawdo w n) = 5 3 m Disch a rge Head Hd = 7 7 + 20 ( re s erv o ir el e v.) = 9 7 m Friction Head H f = assume 1m

28. “ Total Dynamic Hea d ” (TDH) Velocity Head Hv = v2 / 2 g • = 1. 14 ^ 2 / ( 2 ×9. 8 1 ) = 0. 7 (n e gl i gi b le) TDH = - 5 3 + 9 7 + 1 + 0. 7 = 4 5 m

29. Pump brake horsepower P= ( TDH × Q ) / ( 10 2 × ef f icie n cy in d ex) P = ( 4 5 × 2. 2 5 ) / ( 102 ×0. 7 ) = 1 . 42 KW Pump br a ke h o rsepow e r = 1 . 9 HP

30. Pump se l ect i on TDH = 45 m Q = 8 . 1 m 3 /hr 4 S R 6 / 13 D u ty p o i n t

31. Test for Quality of Water

32. TEST FOR S AND The well shall be al l owed to rest for at l e ast o n e h o ur, t h en p u m p i n g sha l l b e gin at the f u ll d esign well yield The wat e r p u m p ed fr o m the well sha l l be su b sta n ti a lly fr e e fr o m clay, silt, a n d sand (< 8.0 m g /l)

33. Test For Yield And D rawdown And Recovery Upon com p le t ion of the p e rma n e n t pr o d u ction wel l , a co n ti n u o us 6 -h o ur p u m p ing t e st shall be con d ucted with the p u m p ing ra t e a n d d rawd o wn recor d ed at a p p ro p ri a te i n t e rvals (b e twe e n min a n d 36 mi n )

34. Test For Yield And D rawdown And Recovery

35. Do u bling well d iam e ter appre c iably incr e a s es well y ie l d DO U BLING WE L L DIA M E T ER 1 % YIE L D INCR E ASE DOUBLING SCREEN LENG T H DOUBLES WELL YIELD WELL DIAMETE R : MYTH FACT

36. Develop m ent of tube we l l Restore a q ui f er, fo l lowi n g d a m a g e d ue to d ril l i n g Red u ce h e ad loss by incre a sing p e rme a bi l ity I n crease well e ff i cie n cy Red u ce dr a wdown a n d cost of extracti n g gr o u n dwa t er Restore / Reh a bi l it a te well d u e t o gr a d u al clog g ing a n d bi o fo u li n g .

37. Development Methods Sur g ing Overp u m p i n g Air L ift (compr e s s ed air) Jett i ng Explosive (rock a q ui f er)

38. H e ad l o ss in a q u i fer H e ad l o ss n e ar scre e n H e a d l o ss thr oug h scr ee n How to redu c e head los s ?

39. Why is it important? M o st sensitive ar e a, where fl o w conv e rg e s a n d is t h e f a stest Wh e re we still h a ve m e a n s t o m o d ify the a q ui f er

40. Ulti m ate Goals M a ke the p o res as b i g a s p ossible so wat e r is fr e e to f l ow. Resu l ts: mo r e fl o w l ower cos t s of o p e r at i on ( r e d u c ed dra wdown = le s s e ne r gy to lift the water = r e d uce d h ydro b i ll)

41. Other goals Rem o ves fi n es Wat e r qua l ity Min i mize a b r as i on on e q u i pm ent ( ex t e n d li f e of pum p i n g a n d p i p i ng e q u i pm ent) Cre a t e s zone of A u t o fi l tr a ti o n

42. Develop m ent Methods Overpu m pi n g Sur g i n g Air L ift Jett i ng Explosive (rock a q ui f er)

43. Overpumping D r awdo w n during operation Increas e d gradie n t D r awdo w n du r ing developmen t

44. Surgi n g

45. Air lift

46. Jetting

47. Overpumping Pros Simple No sp e cial eq uiment Cons No r eve rs e flow No ag i tat i on of soil p a rt i c l es L o w e n e r gy imp a ct Low eff i ci e n c y Req uire s r e mo v al of fi nes

48. Autofi l tration

49. Surging Cons Flow b y p ass Low le v el of impa ct Rela tiv e l y L o w ef f ici e n c y Requ i res rem ova l of fi nes Pros Simple te c h n o l o gy Low Cost

50. Air Lift Pros Effici ent Met h od Combine rem ova l of fi nes Easy to ad j u st/c on t rol en e r gy l eve l Cons Req uire s “ so p h istic at e d ” Equip ment (e . g. co mp r e s so r) Req uire s g o od under s tandin g of aq u i fer c o n d i ti ons Does n ot tar get sp e cific s c ree ned zones

51. Jetting Pros Most E f f ic i ent Method E a sy t o adjust / control e n ergy l e vel E a sy t o target spec i fic screened zone E n h a nce moveme n t o f particles “ dee p” i n to the aq u ifer. Screens des i gn e d for jetti n g (V-w i re) Cons Req uire s “ so p h istic at e d ” Equ i pm ent ( e.g. co mp r e s so r) Req uire s g o od un d e rs ta n d i ng of aq u i fer c o n d i ti ons Requ i res rem ova l of fi nes

52. Wrap Up Devel o p m e n t is very im p ort a nt Immmedia t ely fo l lowin g well co mple t ion As part of t h e mainte n a nce of the well Devel o p m e n t is very com p lex a n d n e e d to be d e sign e d pr o p e rly to be e f ficie n t

53. U n ac ceptable wellhead

54. Acc e ptable wellhe ad