EP2031138A1 - Use of glass balls for filling the annular space between filter pipe and borehole wall for drill holes for gathering water - Google Patents

Abstract

The well has a filter pipe (4), which is inserted in a well bore. An annular space is filled between a borehole wall (2) of the well bore and the filter pipe by glass beads (3). The glass beads are arranged in direct contact with the borehole wall. The glass beads are filled under the insertion of the pipe in the well bore remain in contact with the borehole wall.

Description

DE 511 302 A teaches a double slot tube filter consisting of an outer copper tube and an inner copper tube, the space between the outer and inner tubes being filled with equal diameter glass balls.

DE 1 301 300 teaches a filter tube with a base body made of asbestos cement or plastic, wherein on the wall of the base body outside a shell-shaped filter layer formed by a gravel pack is arranged.

DE 198 53 211 C2 shows a well pipe with extending in its longitudinal direction within its wall and spaced over the circumference of the tube spaced bars, wherein the wall is made of polymer-bound gravel-like grains. The well pipe has at each of its ends a connecting portion consisting of polymer concrete and at its connecting portions a filter-formed portion is arranged, which also consists of polymer-bound gravel-like grains.

DE 453 876 teaches a well filter of individual superimposed, held together by long bolts filter baskets that have a gravel filling.

For the extraction of groundwater, it is necessary to drill vertical holes in the aquifer. In these holes removal tubes made of steel or PVC are installed. A part of the pipes has openings, so that water can flow as unhindered as possible from the underground into the construction pipe. These Pipes are referred to as filter tubes. In order to be able to pump permanently clear water from the well, it is necessary to fill the annulus between the slotted tube and the borehole wall with a suitable filter sand or gravel. The requirements for the filter sand or gravel are listed in DVGW W 123 under point 5.3.2.2 (ISSN 0176-3504).

• Funktionssicherheit, d.h. Durchlässigkeit und Sicherstellung der technischen Sandfreiheit
• Beständigkeit, auch gegenüber aggressiven und kontaminierten Wässern
• Chemische und physikalische Stabilität, Alterungsbeständigkeit
• Physiologische Unbedenklichkeit
• Gute Einbaubarkeit, Handhabbarkeit
• Lagestabilität
• Exakte Positionierbarkeit
• Gute Transportierbarkeit
• Gute Lagerfähigkeit
• Gute Nachweisbarkeit
• Keine nachteilige Beeinflussung anderer Brunnenbauteile

These would be:

• Functional safety, ie permeability and ensuring the technical sand freedom
• Resistance, even to aggressive and contaminated waters
• Chemical and physical stability, aging resistance
• Physiological safety
• Easy to install, easy to handle
• positional stability
• Exact positioning
• Good transportability
• Good shelf life
• Good detectability
• No adverse effect on other well components

In order to meet these requirements, according to the current state of the art, sand and gravel according to DIN 4924 are to be installed in the area of the aquifer covered with the filter tube.

The scope of application of DIN 4924 applies to sands and gravels for the production of gravel beds in well construction.

So far, only the naturally derived material sand or gravel is used for the backfilling of filter tubes in drilling for the purpose of obtaining water.

• um einen möglichst großen Porenraum für die Durchlässigkeit des Wassers zu erreichen, sollten die Sande und Kiese eine möglichst kugelige Form besitzen. Dies ist in der Praxis durch das natürliche Entstehen des Materials kaum gegeben. Es sind zahlreiche nichtrunde Bestandteile im Kies- bzw. Sandmaterial enthalten, die wiederum die Porenräume stark verkleinern. Selbst laut DIN 4924 sind Unterkornmassenteile laut Tab. 1 von 12 % erlaubt. Die Form der Körper wird in der DIN 4924 nur bis zur Korngröße von 5,6 mm als "kantengerundet" (Pkt. 4) gefordert.
• Da das Material in Kiesgruben gewonnen wird, ist es nicht vermeidbar, daß es nicht absolut sauber seinem Verwendungszweck als Schüttgut im Lebensmittelbereich Wasser zugeführt werden kann. Es muß nach dem Einbringen erst langwierig klargespült werden.
• Quarzkörner sind rissig und besitzen Einschlüsse, die ein schnelles Zerspringen der Körner verursachen können.

However, this material has the following disadvantages:

• In order to achieve the largest possible pore space for the permeability of the water, the sands and gravels should have a spherical shape as possible. This is hardly possible in practice due to the natural origin of the material. There are numerous non-round components in the gravel or sand material, which in turn greatly reduce the pore spaces. Even according to DIN 4924, undersize parts are allowed according to Tab. 1 of 12%. The shape of the body is required in DIN 4924 only up to the grain size of 5.6 mm as "edge rounded" (Item 4).
• Since the material is obtained in gravel pits, it is unavoidable that it can not be supplied absolutely clean to its intended use as bulk material in the food industry. It must first be cleared thoroughly after the introduction.
• Quartz grains are cracked and have inclusions that can cause the grains to crack quickly.

The invention specified in the claim is based on the use of glass beads instead of the gravel and sands described in DIN 4924.

• Glaskugeln haben eine annähernd ideale kugelige Form und besitzen damit einen größtmöglichen für die Wassergewinnung nutzbaren Porenraum.
• Glaskugeln sind in absolut gleichen Durchmesser herzustellen. Dies hat den Vorteil, daß selbst bei dichtester Lagerung die Porenräume bei ca. 40 % des Volumens liegen. Keine Unterkörner können diesen Raum ausfüllen. Dies verhindert außerdem auch unerwünschte nachträgliche Setzungen des Materials. Alle für die Trinkwassergewinnung benötigten Durchmesser können in der geforderten Materialqualität gefertigt werden.
• Weiterer Vorteil des gleichen Durchmessers ist, daß das Material beim Einbau in die Bohrlöcher exakt auf den anstehenden Boden angepaßt werden kann. Über- oder Unterkorn wie beim Kiesmaterial ist nicht mehr vorhanden.
• Die Glaskugeln berühren sich nach dem Einbau gegeneinander nur an einem minimalen Punkt. Dies erleichtert später notwendige Reinigungen des Füllmaterials bei notwendigen Brunnenregenierungen (DVGW-Regelwerk W 130).
• Die im DVGW-Regelwerk W 123 unter Pkt. 5.3.2.2 geforderten Eigenschaften an Schüttgüter im Brunnenbau werden durch Glaskugeln in höherem Maße erfüllt als durch die bisherige Kiesschüttung. Dies wären nochmals im Einzelnen:
• Funktionssicherheit, d.h. Durchlässigkeit und Sicherstellung der technischen Sandfreiheit
• Beständigkeit, auch gegenüber aggressiven und kontaminierten Wässern
• Chemische und physikalische Stabilität, Alterungsbeständigkeit
• Physiologische Unbedenklichkeit
• Gute Einbaubarkeit, Handhabbarkeit
• Lagestabilität
• Exakte Positionierbarkeit
• Gute Transportierbarkeit
• Gute Lagerfähigkeit
• Gute Nachweisbarkeit
• Keine nachteilige Beeinflussung anderer Brunnenbauteile
• Das teilweise Verschließen der Filterschlitze von Ausbaurohren durch Unterkornanteile des Schüttmaterials wird komplett verhindert. Dadurch kann das Wasser ungehindert mit niedrigerem Widerstand in die Filterrohre strömen.

The use of glass beads has the following advantages:

• Glass balls have a nearly ideal spherical shape and thus have the largest possible pore space for the production of water.
• Glass balls are to be made in absolutely the same diameter. This has the advantage that even with tightest storage, the pore spaces are about 40% of the volume. No subgrains can fill this space. This also prevents unwanted subsequent settling of the material. All diameters required for drinking water production can be manufactured in the required material quality.
• Another advantage of the same diameter is that the material when installed in the holes can be adapted exactly to the upcoming soil. Over- or undersize grain as gravel material is no longer available.
• The glass balls touch each other after installation against each other only at a minimum point. This facilitates later necessary cleaning of the filling material in case of necessary well regeneration (DVGW regulation W 130).
• The properties of bulk solids in well construction required by DVGW W 123 under 5.3.2.2 are more effectively met by glass spheres than by previous gravel packing. This would be again in detail:
• Functional safety, ie permeability and ensuring the technical sand freedom
• Resistance, even to aggressive and contaminated waters
• Chemical and physical stability, aging resistance
• Physiological safety
• Easy to install, easy to handle
• positional stability
• Exact positioning
• Good transportability
• Good shelf life
• Good detectability
• No adverse effect on other well components
• The partial closing of the filter slots of removal tubes by undersize portions of the bulk material is completely prevented. This allows the water to flow unhindered with lower resistance in the filter tubes.

A further embodiment of the invention is that the glass beads are not poured into the annulus behind the filter tube, but with suitable materials such. Bulk baskets, industrial materials or composites are attached to the filter tube before the tube is installed.

An embodiment of the invention is in as FIG. 1 attached drawing. FIG. 2 and FIG. 3 represent the enlargement of the pore space and, consequently, the improvement of the permeability when using glass beads.

• Fig. 1: Schnitt durch Bohrloch zur Grundwassergewinnung
• Fig. 2: Porenraum bei Verwendung von Glaskugeln
• Fig. 3: Porenraum bei bisher eingesetztem Verfüllmaterial gemäß DIN 4924

Show it:

• Fig. 1 : Section through borehole for groundwater extraction
• Fig. 2 : Pore space when using glass beads
• Fig. 3 : Pore space in previously used backfill material according to DIN 4924

Claims (2)

Well for drinking water production, consisting of a filter tube, which is introduced into a well bore,
characterized in that
the annular space between a borehole wall of the wellbore and the filter tube is filled with glass spheres, wherein the glass spheres are arranged in direct contact with the borehole wall. Use of glass balls for filling the annular space between a borehole wall of a well bore and a filter tube inserted therein, wherein the glass beads are filled after insertion of the tube into the well bore while contacting the borehole wall.

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