 |
2007 Ground Water Summit |
Tuesday, May 1, 2007 : 2:50 p.m.
Patented Solution for Horizontal Directional Drilling of Water Wells
Patented solution for horizontal directional drilling of water wells
In general, the extension of water aquifers is horizontal and water wells are vertical. However, recent developments in Horizontal Directional Drilling (HDD) techniques, drilling fluids and water well design, have made the horizontal directional drilling of water wells a reality.
The patented method for horizontal directional water well drilling is the result of a joint research and design effort by water supply company Oasen (Gouda, the Netherlands) and partners, i.e. a drilling company, an engineering company and a geotechnical research institute.
A key issue in the development of the technique was to find the right drilling fluid: a fluid that is non-clogging, easy tot remove and has a minimal growth potential for bacteria. A series of tests revealed a substitute for bentonite. It possesses equal strength, required to drill the well, but it’s easier to remove afterwards. The drilling fluid, based on polysaccharide is oxidized with hydrogen peroxide during the development of the well. This, together with rigorously flushing, prevents bacterial growth. Test results on field-scale showed an excellent specific yield and a reduced bacterial growth below drinking water requirements within 3 weeks.
In this field-scale experiment a vertical well was drilled identical to the designed horizontal well: identical dimensions, drilling fluid and development methods. Both wells using a stainless steel continuous slot rod based filter. The slots are selected to hold back about 40-70% of the measured grain size of the aquifer, resulting in a natural gravel pack.
The method has been proven suitable for medium to coarse grained unconsolidated sandy river deposits (>300 µm). The cost of the horizontal well is projected to equal that of 11 (small) vertical wells. Oasen plans to employ the above described technique to renovate its well field at Zwijndrecht within the near future.
In general, the extension of water aquifers is horizontal and water wells are vertical. However, recent developments in Horizontal Directional Drilling (HDD) techniques, drilling fluids and water well design, have made the horizontal directional drilling of water wells a reality.
The patented method for horizontal directional water well drilling is the result of a joint research and design effort by water supply company Oasen (Gouda, the Netherlands) and partners, i.e. a drilling company, an engineering company and a geotechnical research institute.
A key issue in the development of the technique was to find the right drilling fluid: a fluid that is non-clogging, easy tot remove and has a minimal growth potential for bacteria. A series of tests revealed a substitute for bentonite. It possesses equal strength, required to drill the well, but it’s easier to remove afterwards. The drilling fluid, based on polysaccharide is oxidized with hydrogen peroxide during the development of the well. This, together with rigorously flushing, prevents bacterial growth. Test results on field-scale showed an excellent specific yield and a reduced bacterial growth below drinking water requirements within 3 weeks.
In this field-scale experiment a vertical well was drilled identical to the designed horizontal well: identical dimensions, drilling fluid and development methods. Both wells using a stainless steel continuous slot rod based filter. The slots are selected to hold back about 40-70% of the measured grain size of the aquifer, resulting in a natural gravel pack.
The method has been proven suitable for medium to coarse grained unconsolidated sandy river deposits (>300 µm). The cost of the horizontal well is projected to equal that of 11 (small) vertical wells. Oasen plans to employ the above described technique to renovate its well field at Zwijndrecht within the near future.
Harrie Timmer, drs., Oasen drs. Harrie Timmer (Emmen, the Netherlands, 1966). College: Free University, Amsterdam, the Netherlands: 1992. Degree: Doctorandus (candidate for the doctorate) geology 1992 - present: Hydrogeologist of Water Supply company Oasen, Gouda, the Netherlands (From 2001-2005: Hydron-Zuid-Holland). Professional focus: hydrogeology, well design and rehabilitation, hydrochemistry. - Chairman of the Dutch "waterworks well society" - Member of the Dutch hydrological organization (NHV) - Member of the Dutch waterworks organization (KVWN) articles: various topics 1995-2006: H2O, Dutch waterworks magazine well clogging by particles in dutch well fields: JAWWA, august 2003