Unconventional measurers sde11


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Unconventional measurers sde11

  1. 1. 1Directorate ofGroundwater Surveys and Development Agency,PuneUnconventional Measures for Source Strengthing
  2. 2. GEOLOGY OF MAHARASHTRA2Deccan Trap 82 %Specific yield 2 to 4 %
  3. 3. GEOLOGY OF MAHARASHTRA• 82 % Deccan trap formation.• Specific Yield not more than 2 to 4 %.• Groundwater is available due to Secondary porosity.• Drinking water sources particularly PWS Wells do nothave adequate yield during summer.• Drinking water sources are dependant mainly on Rainfallin case of less Rainfall sources gives inadequate yield orget’s dried in summer .• Hence these sources are need tobe strengthen bydifferent measures which are conventional &Unconventional .3
  4. 4. Conventional Measurers Deepening of Wells . Augmentation of existing Schemes by Horizontal &Vertical bores In wells . Construction of new Bore well & Dug well . Check dams , Percolation tanks, Earthen nala bunds, under ground bandharas etc. Augmentation of existing P.W.S4
  5. 5. Following unconventional techniques have beendeveloped for the strengthening of drinking watersources.1. Bore-blast-technique.2. Jacket well -technique3. Stream blast- technique.4. Fracture Seal Cementation5. Hydrofracturing to bore wells .6. Artificial recharge of bore well & dug well byflooding , Rainwater harvesting , Rechage shaftetc.Implemented as per location and Characteristicsof the aquifers. 5
  6. 6. GSDA’s SOLUTION SINCE 1983Unconventional Measurers forDrinking Water SourceStrengthening.6
  7. 7. Unconventional Measurers forDrinking Water Source Strengthening.• Most suitable Techniques to improve thestorativity and transmissivity of the aquifers inhard rock terrain.• GSDA developed and implemented first suchscheme during 1983 in the Saraste Village ofNashik District.• Since then 2492 such projects have beenimplemented by GSDA.7
  9. 9. 1.Jacket Well Technique (JW)• Jacketing of well with theblasted bore holesincreases effectivediameter of the wellthereby improves thestorativity andtransmissivity of theaquifer. 9
  10. 10. Jacket well Technique10
  11. 11. Boreholes are drilled around the targetedwell to a depth little less than the depth ofwell.• Subsequently blasting is carried out to createartificial fractures in the compact rocks.• These bores are drilled either in circular, semicircular or any other desired pattern dependingupon the prevalent topographical and hydrogeological conditions.• Explosives of required strength and quantity areused to create maximum fractures and to inter-connect them.11
  12. 12. 12• Sand is generally staved in the boreholes for effectiJacket well
  13. 13. 13
  14. 14. 2.Bore Blast Technique (BBT) :-• Bore blast technique is adopted to createmore storage space for groundwater inmassive and crystalline hard rocks byfracturing.14
  15. 15. 15Boreholes forblastingSourcewellUndergroundbandharaHighly weatheredzone soilTopviewModeratelyweatheredzoneHighly weatheredzoneSourcewellGroundlevel
  16. 16. • Hydrogelogicaland Geophysical survey has to be carried out to know r• Bores are drilled in staggered pattern.• suitable explosives to be lowered in 2 to 3 sections for e16
  17. 17. Bore Blast Technique17Bore Blast Technique
  18. 18. Bore BlastTechnique18OK: SIGNAL (Red Flag) Before BlastingBore hole Blasting
  19. 19. • This technique is applied in areas wherelandforms are mostly hilly.• Being a high cost measure this techniqueshould be adopted to provide drinking water,when no other measure is feasible/possible.19BBT
  20. 20. 3.Stream Blast Technique ( SBT):-• Generally, drinking water wells are situated on nallabanks.• At some places, the groundwater flowing below thenala bed has no hydraulic connectivity with the well,and the well becomes dry or partially dry duringsummer months.• Such well can be rejuvenated by this technique,known as stream blasting.• In this technique, the area of nalla bed within thevicinity of well is investigated geophysically andgeohydrologically. 20
  21. 21. Stream Blasting21
  22. 22. • Then bores are drilled in the nala bed to adepth of open dug well.• These bores are in staggering pattern to getmaximum blasting effect in minimumnumber of bores.• Pattern and number of bores is decidedconsidering the hardness of the strata to befractured or shattered.• These boreholes are further charged withexplosives and blasted to create fracturesand joints artificially. 22
  23. 23. • These artificially created fractures getconnected to the well and divertgroundwater from nalla to the well.23SBT
  24. 24. Design Calculations.• Calculate the volume of rock of each bore-hole tobe fractured by blasting.• For example if,• Hard rock depth (h)= 7 meters,• Spacing between the bores = 4 meters• Radius = 2 mtrs.• Therefore volume of rock = ¶r2x h• = 22/7 x22x 7 = 88 m3 .• Quantity of explosives required is 150 gms.per m3. ( 0.150 Kg)• Therefore for 88 m3 rock quantity of explosiverequired = 88 x 0.150• = 13.20 kgs.24
  25. 25. Continued• The diameter of the bore-hole is 100-115 mm.• Use 83 mm dia. slurry explosives (Class 2), theweight of each bag being 2.78 kgs.25
  26. 26. Continued• Weathered Zone should not be charged.• 1.5 to 2.0 meters below the depth ofweathered zone, explosive charge of 2.78 kgs.= 1 bag should be provided.• Distance between two explosive charged i.e.section interval may be taken as 2-3 meters.• Bottom charge should be more.26
  27. 27. 270 GL10 mExplosives charge2.78 KgsExplosives charge5.56 KgsExplosives charge5.56 KgsSand StemmingWeatheredZone2 m5 m
  28. 28. Design and Methodology of unconventional Blastingtechnology. Bore-hole drilling pattern is decided asper site condition and, this pattern mayvary from site to site depending upon thegeological conditions. Bore-holes of suitable diameter (100-150mm) are drilled to the required depth orto a depth of shallow aquifer.28
  29. 29. • Generally 10-15 meters deep drilling ofholes would be adequate.• Distance between the bore-holes i.e.spacing is decided as per site conditionsand based on past experience.• Generally spacing is kept 3-5 meters inbasaltic hard massive rock.29
  30. 30. Continued• Staggering pattern of bore-holes ispreferred.• Suitable type of explosives andexplosives charge should be lowered intobore-holes to be blasted.• At any time, not more than 5-6 bore-holes should be charged and fired(blasted).30
  31. 31. Continued Charging and blasting operations shouldbe started from the bore-hole which islying at the centre of the site and thenextended Radially in all directions till theoperations are complete. Controlled blasting of the bore-holes ispreferred and if this is not possible or notpracticable then, instantaneous blastingmay be carried out.31
  32. 32. Continued• Blasting in hard rock only should becarried out i.e. weathered zone shouldnot be charged and blasted.32
  33. 33. Fracture Seal Cementation• Groundwater migration through a network ofshallow depth aquifer from the discharging locationis arrested by this technique.• Cementation may be defined as injection of cementslurry under pressure to fill voids, cracks seams,fissures or other cavities.• The result is to ensure water tightness byestablishment of very low permeability.33Fracture FSC-1 FSC-2
  34. 34. Hydrofracturing.Hydrofracturingis a Greek word.Hydro means water.Hence Hydrofracturing meansFracturing with the help ofwater.34
  35. 35. Hydrofracturing is a process in whichpressurized water is injected into thebore well to increase the permeability ofthe consolidated material or a relativelyimpermeable unconsolidated material.Which improves the yield of the borewell. Success ratio is about 65 %.35
  36. 36. Successful borewell ?• Successful borewellshould providehygienic, safe, potabledrinking water to 250souls through out theyear , 40 liters per day• maintaining swl lessthan 36 m.for easieroperation of the pump.< 36 mtrsB/w
  37. 37. Poor yielding Bore wells1.The b/w isisolated from thenearby waterbearing zone by amassive rockinterveningbetween the b/wand waterbearing zone.massive rockwater bearing zoneB/w
  38. 38. Poor yielding Bore wells2.The aquifer containsclosed fractures orthe b/w is poorlyconnected to anearby waterbearing zone due tothe low permeabilityof the interveningrock between themwater bearing zoneB/waquifer contains closed fractures
  39. 39. Poor yielding Bore wells3.The bore well yieldlow because some ofthe open fracturesarechoked withaccumulates such asclay,resulting inlarge reduction ofhydraulicconductivity ofaquifer-fracturesystem.Choked aquifer.water bearing zoneB/w
  40. 40. • All these bore wells falling underabove three categories can beconsidered for the treatment ofhydrofracturing techniques toimprove the yield.Because
  41. 41. BecauseHydrofracturing is a process in which pressurizedwater is injected into the borewell to increasethe permeability of the consolidated material ora relatively impermeable unconsolidatedmaterial.Which improves the yield of the borewells.
  42. 42. Methods of improving efficiency ofthe bore wells.1.Augmentation of bore wells.2.Improvement of storage capacity ofthe aquifer.
  43. 43. Methods of improving efficiency of thebore wells. ( Continued.)1.Augmentation of bore wellsby improvement in the yield.a) Sectional blasting.b) Hydrofracturing.2. Improvement of storage capacity ofthe aquifer by AcceleratingGroundwater movement andrecharge --use of HF
  44. 44. Methods of improving efficiency of the bore wells.( Continued.)1. Augmentation of borewells by improvement in theyield.a) Sectional blasting.Sectional blasting meansblasting of a bore well atparticular section to improvethe permeability of that zone.ExplosiveExploderBore well
  45. 45. • Results of sectional blasting are more orless futile,as blasting induced fracturescould penetrate to a distance of 2-3meters only, which is not sufficient forconnecting a Bw to nearest water bearingzone.• It is not possible to control thepropogation of fractures because this is aninstant action.Methods of improving efficiency of the bore wells.( Continued.)
  46. 46. • Most of the bore wells taken for the drinkingwater purpose are in the vicinity of villageshence sectional blasting is having restrictedscope due to safety precautions.Sectional Blasting . Continued.
  47. 47. Hydrofracturing.HF is carried out bysealing a section ofB/w & pumping waterat high discharge rateinto the sealed offsection.So thatenormous pressure iscreated into theconfined space whichcreates the fractures.47
  48. 48. Hydrofracturing.48
  49. 49. 49Due to creation of network of fracturesin the hard rock by Hydrofracturing:• Yield of the BWs can be improved.• Intake and storage capacity of aquiferimproves, which in turn improvesrecharge.• Hence the Bw become a sustainablesource
  50. 50. Hydrofracturing.• To understand the principles of HF agood example is of pumping air intoa balloon more than its capacity willresult into the bursting of balloon.50
  51. 51. 51Water tanker.HF UnitInflated Packerrubber sealsHydraulichand pump.Pressure gaugeHydraulicpackercylinder
  52. 52. 52Hydrofracturing UnitPrimemoverHigh PressureWater Injection PumpOver headCraneGenerator Set
  53. 53. 53
  54. 54. 54Line DiagramWater TankerBooster PumpHigh Pressure water injection pump(WOMA Pump)Hydraulic PackerHF UnitHigh Pressure Hose.
  55. 55. 55LoweringofDummy Tool
  56. 56. 56LoweringofPacker
  57. 57. 57TeeDrain valvePressure Gauge.Then release outletvalve oftee to drain waterunder pressure in theB/w.When pressure ofdrainage water fallsdownrelease packers and setit tonext section and repeatthe process.
  58. 58. HF ObservationsFluid pressure inthe sealedsegmentinstantaneouslyincreases tillbreakdownpressure(pc) isreached.58PressureTimeBreakdownpressure(pc)
  59. 59. HF ObservationsThen the fluidpressuresuddenly drops(pf)indicatingthat ahydrofracture isinitiated on theb/w wall.59PressureTimeBreakdownpressure(pc)(pf)
  60. 60. HF ObservationsOn further pumping ofthe frac fluid thefracture propogates.Itmay be observed thatthe pumping pressureremains constant at pfduring propogationhence it is called as thefracture extensionpressure.60PressureTimeBreakdownpressure(pc)(pf)
  61. 61. HF ObservationsWhen the pumping isstopped and the B/w isisolated from thepump by shutting inthe valve in betweenthem then the fluidpressure i.e. pfinstantaneously dropsto psi called as shut inpressure.61PressureTimeBreakdownpressure(pc)(pf) psi
  62. 62. 62TimePressurePcpfpsiFluid pressure suddenly rises till thebreakdown pressure reached = pcThen the fluid pressuresuddenly drops= pfthis is due to fracturingof rock.When the thepumping isstoppedthen the pf dropsto psi i.e. shut inpressure.
  63. 63. • During Hydrofracturingaverage dynamic apertureobserved is 3 mm.However on releasing ofpressure the fractures closesback.63Post HF ResultsButthe fractures do notcome backexactly to their originalpositions.
  64. 64. which act as a channel to transportgroundwater from the near by waterbearing zone into the B/w.64Thisimperfect closure impartsconsiderableImprovement in the permeabilityPost HF Results
  65. 65. 65ThisresultsinRejuvenatingthe B/w.
  66. 66. • The well yield after HF is mostlydepends on the fracture created aswell as on the permeability of theaquifer.66Post HF Results
  67. 67. HF Analytical Solutions.We can Predict required frac fluid pressure, toinitiate a vertical hydrofracture .Models provide theoretical basis to determine thelength and aperture of fracture as a function of :Frac fluid discharge rate.Pumping time.Frac fluid viscosity.Aquifer rock propertiesAquifer fluid properties.67
  68. 68. • Also it predicts the distance to whichthe pre existing fracture reopen.• Requirement of max pumpingpressure,time of pumping,optimaldischarge rate have been worked outfor this.68HF Analytical Solutions .Contd
  69. 69. • Length and aperture of fracturecreated is idealized as below:• fracture length is directlyproportional to the discharge rate fora given time of pumping.• Q is constant in HF as 335 LPM69
  70. 70. For the Propagationup toPumping Time Requiredin minutes.100 m 20200 m 40300 m 6070
  71. 71. • It can be decided the Q and timerequired to get a particular fraclength.71HF Analytical Solutions .Contd
  72. 72. Conclusion• For rejuvenating the low yielding borewellsHF is the most effective technique, providedHF is carried out by pumping frac fluid atfairly large discharge rate of 400-600 LPM.• Success depends on the geohydrologicalconditions of the aquifer.• Efforts will be futile if there is no waterbearing zone near by.72
  73. 73. Conclusion• Every effort should be made to know thesuccess and failure of the HF.73
  74. 74. These are few methodsGSDA is using for thestrengthening of Sources.74
  75. 75. 2.AcceleratingGroundwater movementand recharge by HF
  76. 76. Accelerating Groundwater movementand recharge by HF• It is established that the HF can beused to improve the rechargeconditions also.• HF• creates new fractures,• cleans existing fractures,• widen and propogates the fractures.
  77. 77. Accelerating Groundwater movementand recharge by HF• In other way the above physicalchanges in the properties lead toimprove the intake capacityand storage capacity of theB/w.
  78. 78. Accelerating Groundwater movementand recharge by HF• It is observed that the intake capacityof the B/w is improved by 3.5 times.• It means the recharge can beimproved up to 3.5 times more byHF .
  79. 79. Sr.No.Particulars Basalt(bars)Granite(bars)1 Break down pressure -Pc 110 1452 Reopening pressure -Pr 70 753 Propogating pressure- Pf 60 404 Shut in pressure- Psi 40 705 Max.H.P.stresses -SH 50 756 Min.H.P.stresses -sh 40 507 Tangential stresses -T 40 70777Values determined for the basalt and granite.
  80. 80. Methodology.• Measure intake capacity of the B/w.• HF the B/w.• Measure the post intake capacity.• Select near by Surplus surface watersource.• Install submersible pump on the B/w(without foot valve.)• Connect delivery pipe to surplus watersource.
  81. 81. Methodology.• Observe that the submersible pump islowered below the level of intakepipe line.• Check the system is leak proof.• Operate the sub.pump for fewminutes and stop the pump.
  82. 82. Methodology.• Reversible flow will start from thesurplus water source to B/w.based onsiphon principle.• Run the system round the clock tillthe surplus water is available.• Detach the pipe line after completionof season.
  83. 83. Schematic diagram ofReverse flow for rechargeOpen well/Village tank/Percolation tank Siphon/PipingBorewellG.L.Submersible pump
  84. 84. Schematic diagram ofReverse flow for rechargeOpen well/Village tank/Percolation tank Siphon/PipingBorewellG.L.Submersible pump
  85. 85. Schematic diagram ofReverse flow for rechargeOpen well/Village tank/Percolation tank Siphon/PipingBorewellG.L.Submersible pump
  86. 86. Siphon in actionDug well water isrecharged into theBore well.
  87. 87. Siphon in actionDug well water isrecharged into theBore well.
  88. 88. Interpretations.• It is observed that the recharge isinversely proportional to the propogationpressure.• Hence while carrying out Hf it can bepredicted that if the propogation pressureis less, the B/w is likely to accept morerecharge.• Normally Dugwells can be taken as asurplus water source for recharge.
  89. 89. Success Stories.
  90. 90. DRINKING WATER SOURCE STRENGTHING AT VILLAGE HIVAREBAZAR DISTRICT AHMEDNAGAR.Design of Bore Blast (BBT)•The area selected in the villageHivare Bazar for blasting is about 5400 sq mt.•The purpose of theProject was to deviatethe shallow aquiferwater at the upper ridgethat was flowing outsidethe watershed .
  91. 91. DRINKING WATER SOURCE STRENGTHING AT VILLAGE HIVAREBAZAR DISTRICT AHMEDNAGAR.Design of Bore Blast (BBT)•The area selected in the villageHivare Bazar for blasting is about 5400 sq mt.•The purpose of theProject was to deviatethe shallow aquiferwater at the upper ridgethat was flowing outsidethe watershed .
  92. 92. • The bore blasting was designed in such a waythat the water underground flowing outsidethe village boundary was deviated towardsthe village by creating artificial fractures inthe compact massive basalt which wasotherwise acting as a barrier for groundwaterrecharge.
  93. 93. • Total 103 bore holes were taken with a depthrange of 5 to 18 Mts.Vertical cross section
  94. 94. SR.NOLOCATIONS13/7/07 14/7/07 20/7/07 31/8/07 15/10/07(Before Project)(After project)Static water level below ground level in meter1Bore Well at up streamside of project3.9 3 4.4 4.4 1.22Bore Well at down streamside of project14 14 0 0 03 Dug well Of Shri.Thange Dry Dry 15 2.55 2.1Monitoring of Static water level of wells around the project siteDate of implementation of BBT project 20th July 2007.
  95. 95. SAROLA PATHAR, TALUKA SANGAMNER,DISRTICT AHMEDNAGAR• Village Sarola Pathar is among the ‘Hard CoreVillages’ where due to adverse hydro geologicalcondition, the inhabitants were deprived from thebasic need of potable drinking water. Theconventional measures like open dug wells and borewells could not fulfill the need• Due to the geomorphologic conditions that are notconducive to support the earlier measures and non-implementation of regional pipe water scheme, thetanker water supply was made since four years tofulfill the village demand during summer.
  96. 96. UCM MEASURES PROPOSED• The measures proposed were examined in the fieldand suitable structures for arresting rain water flow,Augmentation of existing borewell by hydrofracturing, augmenting the ground water storage ofexisting open well, cutoff wall by bore well withfracture seal cementation, recharging the dyke at upstream by rain water harvesting through village tank,feeding the harvested water to dyke throughrecharge trench and plugging out flow from the dykeat down stream were proposed for implementation.
  98. 98. • In this village three measures have been completedsuccessfully. The dyke which was running from SE-NW wasfound to be a carrier dykes in nature. This dyke was pluggedwith the help of an unconventional measure, fracture sealcementation. (F.S.C.) In this method number of borewells aredrilled on the downstream of the source well and cementslurry is injected in the borewells with pressure. The pluggingof dyke has restricted the movement of subsurface flow.• After the F.S.C. this dyke was fed with existing villagetank water by trenching, this made the availability ofgroundwater to the existing source, thus the groundwatersource was rejuvenated.
  99. 99. • The last measure that was taken up was the hydro fracturingof the existing bore wells. A new bore well drilled in March1993 yielded 19191 lph of water. A power pump of suitablehorsepower was installed on this high yielding bore well and amini pipe water supply scheme was established on thissource. This indicates that there was an overall saturation ofgroundwater in the project area with a definite increase inthe availability of groundwater after the project. As on todaythere is adequate drinking water in the village.• The impact of hydro fracturing was seen with a suddenrise in the water level. The poor yielding bore well no. 3 hasbecome a sustainable source for drinking water.
  100. 100. Graph showing differences in the yield of bore wellafter F.S.C. & Hydro fracturing0100020003000400050006000Borewell1Borewell2Borewell3Yield in LPH PriorYield in LPH After
  101. 101. THANKS102