Wells and Pump Servicing Tifft Symposium September 23, 2015

Transcription

1 Wells and Pump Servicing 2015 Tifft Symposium September 23, 2015

2 Well s Birth Certificate Completion Report

3 Well Performance Testing Performed during and after construction to determine safe yield and sand production Flow tests are conducted periodically to determine if well performance or condition of well has changed

4 Typical Well Operation Depth to Static Water Level Static Water Level Cone of Depression Drawdown Drawdown Curve Pumping Water Level Or Dynamic Water Level Water-Bearing Formation Well Screen

5 Pump Testing Certified Test- Performed at Factory to insure Design Point Achieved. Field Test- Performed for or by owner to confirm yield (gpm) & head (TDH) and Efficiency

6 Last Tested 5/10/2011 Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. FLOW RATE, Q (GPM) 1224 MOTOR SPEED, NM (RPM) 0 GAUGE CORR. (PSI) 0 CORRECTION (FT) 0 PUMP PRESSURE (PSI) 64 PUMPING LEVEL (FT) 10 PUMPING LEVEL CORR (I.E.-0.N') 0 VOLTAGE L1L2 490 L2L3 491 L1L3 489 AMPS L1 83 L2 81 L3 82 POWER FACTOR L L L Motor Efficiency 93 **** MISCELLANEOUS DATA *******

7 WHAT TO CHECK if Flow Rate has changed: Discharge pressure Pumping level using Altitude gage Altitude gage Is Motor oil burned or very dark? Gate valve Closed? PRV open fully? Pipe Transmits Water Line shaft transmit power from motor to Bowl Actually moves water Well Casing Bottom of Air line usually set at pump suction is connected to a Altitude Gage Screened in Formation

8 Pump Mechanical Failures Broken shaft on DW turbine pump sand locks impellers, sudden torque will shear weak metallurgy of shaft prelube failure on water lube pump Low pumpage Screen can t pass water fast enough- dissolved oxygen often visible Loose impeller Hole in pump columncloudy water Blow off valve failure Also: telemetering failures, limit switch on blow off, bad starter contacts

9 Pump Column Pipe Inspection Check for erosion of threads and faces Of pipe and couplings

10 Bowl Assembly Inspection Check & measure Impeller skirts & bowls for Excess clearance for normal or abnormal wear

11 Bowl Assembly Failures The effects on an Impeller of electrolysis

12 Confirming Well Measurements Well Depth Well Diameters: Casing Inside I.D. Screen ID Screen Slot Size

13 Direct Water Level Measurement Direct: Most positive indication of water levels. Using an M Scope (Electronic Telltale). Open wire probes make contact with water closing circuit which is indicated when light comes on or milliammeter indicates current.

14 Indirect Water Level Measurements Air Valve Airline 1) Static Level 2) Pumping Level Indirect: Measure pressure required to displace water from inside of airline. Altitude gage which reads in feet of water gives indirect measurement of water level which has to be subtracted from airline length to give actual level. Example: 180 airline Static \ 150 Gage Reading / 30 Actual Static Water Level that would be measured from grade using M Scope Direct reading gage which also reads in feet of water; but 0 point is set at length of airline yielding actual water level.

15 Well Inspection Tools TV Inspection Check for casing Scale condition, screen Slot erosion

16 Well Casing Plumbness A straight vertical hole permits the pump to be located at the desired depth, and prevents pump damage Minimize wear on pump shaft Minimize wear on pump bearings Minimize wear on discharge casing One way to test- lower a 40 length of pipe to pump's depth. Diameter of the pipe should be 1/2 or less than the casing diameter Allowance <2/3 of inside diameter per 100 (common to have deviation at <6 per 100 of depth, measured to 100 below the deepest anticipated pump setting)

17 Well Plumbness Testing Should always be done Especially if considering Adding to pump setting

18 Well screen 1 Wells in unconsolidated (sand and gravel) formations need well screen Screens allow the maximum amount of water to enter the well with a minimum of resistance & without sand passage during pumping Stainless steel (steel, chrome, nickel), Everdur (copper,silicon,manganese)

19 Gravel packing (Gravel wall wells) 2 HOW: Outer casing in-place lower screen& center gravel in annular space between screen and outer casing extend gravel several feet above screen while outer casing is pulled back attach screen to inner or working casing & place pump into inner casing

20 Well Development Methods for Improving Production & Yield Surging and Pumping with DWT Pump Air-lift Pumping Solid Block Surging and Bailing Jetting and Pumping All the above with or without chemicals to enhance effectiveness

21 Some common arrangements Features are often combined into a single well Semi-double cased well Driven well Tubular Well

22 Well Disinfection Contamination is introduced From surface By tools, including mud pit By casing By screen Disinfect by adding enough chlorine to produce 50 ppm - get solution into contact with casing, pump, and discharge piping Chlorinate gravel pack as its being placed or use prechlorinated gravel pack

23 Well Abandonment Long Island(Nassau & Suffolk)NYSDEC Region1 Contact NYSDEC office for specific requirements, which generally include: Fill screen with clean gravel and calciumhypochlorite granules Fill casing with either neat cement grout or drilling clay to within 5 feet of grade. Cut casing below grade and fill with concrete plug.

24 Pump Service Options Replace Complete Rebuild bowl & replace components Shown: water lubricated pump head for a vertical deep well turbine pump application

25 Well Appurtenances-1 Water level drawdown measurement Air-line Casing vent- screen Crispin valve Feed line for chemicals Water line for pump shaft bearing prelubrication Crispin Valve

26 Centrifugal Pumps- Basic Elements and Operation Suction nozzle Impeller eye Impeller (rotating segment) Volute or diffuser (deep well turbine) Discharge nozzle Water enters through suction & exists discharge

27 Deep Well Turbine A deep well turbine is a combination of several stages of centrifugal impellers connected in series to a common shaft. There is no theoretical limit to depth.

28 Submersible Pump Advantages- OK for less-plumb wells. Water in well lubricates pump and cools motor Disadvantage- prone to lightening, removal issues

29 Considerations in a Pump Installation 1 Determine pumping levelpump element must be below maximum drawdown in well Place pump to allow ready removal- roof section removable in well house Safeguard against flooding Concrete foundation w/foundation bolts

30 Some Well Failures Casing failure- corrosion (salt water), electrolysis, soils Screen failure- corrosion, erosion(sand) Everdur years Redrill, set new screen or screen liner Screen plugging- acid treat Pumping sand- redevelop, may be a screen failure Catastrophic check valve failure may damage screen system water forced out through screen

31 Causes of Screen Failure Casing failure- corrosion (salt water), electrolysis, soils Screen failure- corrosion, erosion(sand) Everdur years Redrill, set new screen or screen liner Screen plugging- acid treat Pumping sand- redevelop, may be a screen failure

32 Other Types of Well Failures Screen Collapse Inner Casing Collapse or Detachment Outer Casing Leak Can allow upper aquifer water to enter well Catastrophic no water Usually only occurs where water quality is very aggressive

33 Treatment Methods Same as original development methods Actually generally needs to be more aggressive Backwashing to Surge & Pumping Jetting & Pumping

34 Major Rehabilitation Types Screen Replacement Development no longer works Screen yields sand Liner Screen Can prolong 25% lower cost

35 Development Procedures High capacity air compressor required to move water at high velocity required to lift solids

36 Development Tools Brushes

37 Air-lift Pumping Pumping Method when trying to move solids from wells when static water levels are deeper than 20 feet

38 Treatment Chemicals Depends on what is causing problem i.e. loss in capacity : Mechanical Usually mineral incrustation requiring the use of HCL or other inorganic ACIDS Organic: usually requiring use of organic acid such as acidic for iron bacteria

39 Before & After Development