NL1032588C2 - Horizontal draw well creation method, comprises use of drilling fluid comprising oxidizable polysaccharide - Google Patents

Abstract

The well is drilled using a drilling fluid comprising an oxidizable polysaccharide and during setting of the well an oxidizing agent is used to degrade the polysaccharide. A method for creating a horizontal draw-well comprises the following steps: (A) drilling a well in a water-carrying region in the presence of a drilling fluid comprising at least one oxidizable polysaccharide; and (B) developing the well by eliminating the polysaccharide, using at least one oxidizing agent to degrade it. Independent claims are also included for the following: (1) Draw-well for water, obtained via this method; (2) Method for drawing groundwater using this draw-well; and (3) Method for storing water by introducing it into a water-carrying region via one of these draw-wells.

Description

Title: horizontal well

The invention relates to the production of a well for water extraction, to a well for water extraction and to a method for extracting water from a water-carrying package.

Various design principles are known for manufacturing a well for water extraction. Three principles are described in Sass and Treskatis, Grundwasser - Zeitschrift der Fachsektion Hydrogeologie 1/2000, p 17-23. The extraction of groundwater, in particular groundwater for drinking water preparation, takes place in the traditional manner by using a vertical well or in some cases a radial well. The capacity of a vertical well is relatively small, so that in general many wells are needed for large-scale water extraction. Consequently, large-scale water extraction requires many pumps, pipes and the like. A radial well consists of a deep shaft up to a maximum of 80 meters below ground level, from which several horizontal filter tubes can be placed in the ground. A greater capacity per well can be achieved with the horizontal filter tubes of a radial well than with the vertical wells, but a radial well is generally relatively expensive and limited in depth and length of the horizontal filter tubes.

Application of a horizontal well which is drilled by means of the HDD technique is in principle more efficient. A horizontal well generally comprises an input conduit that is drilled obliquely into the ground into a water-bearing package. In the water-carrying package, the inlet pipe passes into a water-permeable tube that runs through the water-carrying package. In principle, the tube may run bent or diagonal through the water-bearing package 25, although for practical reasons the tube usually extends at least substantially in a horizontal direction.

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Compared to vertical wells, there is in principle a greater risk of clogging in horizontal wells as a result of the lagging of the borehole, as a result of which the capacity can decrease. Sand supply and / or guaranteeing the biological quality of the water can also be a problem, in particular if the well is intended for drinking water extraction. In particular, the use of horizontal wells in soils with relatively low permeability, such as moderate to fine-sand soils, in which removal of the plaster with conventional techniques is difficult, is therefore generally impossible in practice in the art because of too high a risk. deemed.

In Grundwasser - Zeitschrift der Fachsektion Hydrogeologie 1/200, pp. 24-34, Sass and Treskatis describe the production of a curved horizontal well for drinking water extraction in a highly permeable aquifer (coarse sand / gravel, with a typical permeability of more than 150 m / day The well is drilled by means of a controlled horizontal drilling technique, which is known in the art as "horizontal directional drilling" (HDD), which uses a drilling fluid that includes a drilling clay.

The inventors have found by means of internal research that the use of a drilling clay, such as bentonite, leads to a limitation of the extraction capacity, which is undesirable, in particular if a well has to be laid in a water-carrying package with a relatively low permeability relative to coarse sand, for example of less than 100 m / day and in particular of less than 80 m / day. In the Netherlands, for example, the water permeability is usually less than 100 m / day, in particular about 20-50 m / day. The inventors have furthermore found that a drilling clay, such as bentonite, is not completely removable after drilling, which is disadvantageous for the capacity of the well, in particular in a relatively low-permeable water-carrying package, such as often occurs in the Netherlands.

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The inventors then attempted to solve this problem by using a water-soluble polymer instead of bentonite. Such a polymer was also found to be not completely removable with conventional development techniques and the biodegradation process of these polymers in often anoxic groundwater of the aquifer is very slow or even not significantly detectable.

It is an object of the invention to provide a new method for manufacturing a water well, in particular a horizontal water well, which can serve as an alternative to known methods.

It is a further object of the invention to provide a water well that has a good capacity, in particular an increased capacity with respect to a comparable well of the same type manufactured in a conventional manner.

It is furthermore an object to provide a water well with a capacity that is retained for a long time.

It is furthermore an object to provide a well from which groundwater can be extracted that is at least substantially sand-free.

It is furthermore an aim to provide a water well from which groundwater of a biologically reliable quality can be extracted.

It is furthermore an object to provide a method for extracting groundwater of a biologically reliable quality.

One or more other objects follow from the description and / or claims that follow.

It has now been found that one or more targets can be achieved by manufacturing a well with the use of a drilling fluid containing a specific aid and then treating the drilled well with a means by which the aid is broken down.

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The present invention therefore relates to a method for manufacturing a water well, comprising - drilling a well in a water-carrying package in the presence of a drilling fluid comprising at least one chemically degradable polymer; and - developing the well, comprising at least substantially removing the polymer, wherein at least a portion of the polymer is chemically degraded.

In particular, the invention relates to a method for manufacturing a horizontal water well, comprising - drilling a well in a water-carrying package in the presence of a drilling fluid comprising at least one oxidizable polysaccharide; and - developing the well, comprising at least substantially removing the oxidizable polysaccharide, wherein at least a part of the polysaccharide is degraded in the presence of at least one oxidizer.

The polymer (polysaccharide) contributes to the physico-chemical properties of the drilling mud (which usually comprises groundwater, bored soil, including sand, clay, loam and / or peat, and the polymer), to be optimized so that the drilling mud meets the well-known requirements that are required to perform an HDD drilling, without the need for bentonite. Among other things, it is important that the borehole be maintained during drilling. Maintaining the hole is ao

It is important that during drilling the drilling installation does not get stuck in a collapsed borehole and to be able to fit a filter in the hole after drilling if desired. In addition, the polymer can contribute to making the drilling mud suitable for applying good plastering and thus limiting the drilling mud loss during drilling. Also, in particular a polysaccharide has a viscosity-increasing effect on the drilling fluid, which helps to effectively remove sand and the like from the borehole.

Because the chemically degradable polymer and in particular the oxidizable polysaccharide is at least substantially removed after drilling and retraction of the filter tube, there is no or a relatively small adverse effect thereof on the capacity of the well. The breaking off makes its adequate removal possible or at least easier.

The invention thus provides a method in which the borehole can be temporarily plastered, which is desirable during drilling. Subsequently, the plastering can again be sufficiently removed within a relatively short time. Removal is important for achieving a high water extraction capacity if desired.

The degradation of the polymer is also important for, if desired, creating a so-called natural overflow from the source during the development of the well. This will be further explained below.

The invention also relates to a well for extracting water, obtainable by a method according to the invention. Such a well is generally essentially free of plastering agent, in particular free of drilling clay and / or of polysaccharides. The borehole wall of the well preferably has a water permeability that is at least substantially equal to that of the surrounding package.

The invention also relates to a method for extracting groundwater, wherein groundwater is extracted from the bottom in which a well (obtained) according to the invention is arranged. Such a method is particularly suitable for the preparation of drinking water. It is surprising that a method using a horizontal well obtained by using a polysaccharide-containing drilling fluid is suitable for recovering 6 drinking water of a good microbiological quality. Polysaccharides (which have been found not to be adequately removable in a conventional manner) form a good substrate for microorganisms whose presence in drinking water is undesirable.

The invention also relates to a method for storing water, wherein water is introduced into a water-carrying package via a well (obtained) according to the invention. Such a method can for instance be used for energy storage

Figure 1 shows schematically a well (obtained) according to the invention with a continuous borehole. A filter tube (1, shown as a dotted line), such as a winding wire filter, is placed therein, at least in a part of the borehole that is present in the water-carrying package. Blind tubes (4, 5) can be placed near the entry point (2) and the exit point (3) to keep the hole open there. Near the entry point 15 (2), and optionally at the exit point (3), a pumping chamber (6) is usually arranged. These parts can be fitted in a manner known per se. In principle, it is also possible to manufacture a well with a blind borehole, in which there is only one entry point and no exit point.

The invention makes it possible to provide a water well with a high capacity and / or a long service life.

The invention makes it possible to extract groundwater that is at least substantially sand-free, in particular also with a high volume of stream.

The invention makes it possible to recover water that has a good biological quality, in particular a biological quality such that the water is suitable for drinking water preparation.

In principle, a method according to the invention is suitable for use in any water-carrying package, i.e. a base layer from which water can be extracted or in which water can be stored. The water-carrying package can be relatively high-permeable, such as in coarse sand or gravel, or relatively low-permeable, such as in moderately fine to fine sand.

In principle, the invention can be applied in soils with a high water permeability, such as a permeability of more than 5 100 m / day, for example 150 m / day or more. In particular, a method according to the invention offers an advantage for manufacturing a well in a relatively low-permeable package, such as a package with a water permeability of 100 m / day or less, in particular of a maximum of 80 m / day, more in in particular from a maximum of 50 m / day. From 10 practical capacity considerations, the permeability is preferably at least 10 m / day, in particular at least 20 m / day.

A method according to the invention is particularly suitable for manufacturing a horizontal well, wherein usually at least the part of the well intended for passage of water (dotted line in Figure 1) in the water-carrying package is at least substantially in a horizontal direction.

The well is preferably drilled with an HDD technique, for example as described in the aforementioned literature.

The length of the part of the well (the filter tube) intended for passage of water can be chosen within wide limits. The length can be, for example, at least 10 m, at least 50 m, or at least 100 m. The maximum length is not critical. The length can be, for example, 300 m or more.

The depth to which the at least substantially horizontal part is applied depends on the depth of the water-bearing layer and can for instance amount to 10 m or more, 100 m or more, or 1000 m or more.

The diameter, the entry angle, the exit angle and / or other geometric parameters can be chosen within wide limits depending on the desired capacity, for example using general knowledge or what has been described in the above literature.

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Drilling is carried out in the presence of a drilling fluid comprising a polymer, in particular a polysaccharide.

A polysaccharide, in particular a chemically unmodified polysaccharide, is readily degradable in situ, in particular by means of oxidation. It is usually easy to remove after drilling, compared to a drilling clay. It is suspected that a less strong adhesion makes it easier to flush the polysaccharide out of the well at least to a large extent. In addition, a polysaccharide can generally be degraded to a water-soluble degradation product that can be sufficiently flushed out.

The chemically degradable polymer is preferably a polymer which, in the presence of a stoichiometric excess of a suitable oxidizer or other agent that causes the degradation, under conditions prevailing in the soil (e.g. about 12 ° C) within a reasonable time (e.g. 15 is sufficiently degraded within a maximum of 4 weeks, in particular a maximum of 2 weeks) to be adequately removed.

Preferred are gums, in particular guar gum, xanthan gum, a polymer with at least about the same rate of degradation as guar gum or xanthan gum in the presence of hydrogen peroxide, or a combination thereof.

More preferably, a polysaccharide with a relatively low branching degree is used, such as xanthan gum or a polysaccharide with a comparable or lower branching degree. Without being bound by theory, it is suspected that xanthan gum and the like are capable of trapping fine particles, such as sand or clay particles, which particles cause the borehole wall to be temporarily plastered. When the gum breaks off, the plastering effect is also at least substantially canceled out, which is desirable in an application according to the invention.

Preferably, the polymer behaves as a Bingham liquid. Xanthan gum is an example of such a polymer. This is advantageous for keeping fine particles in suspension if the drilling fluid is at rest during the drilling process.

The concentration of the polymer, in particular the polysaccharide, can be chosen within wide limits, depending on the soil to be punctured, etc. The concentration is usually at least 1 kg / m3 of liquid, in particular at least 2 kg / m3 of liquid . The concentration is usually a maximum of 30 kg / m3 of liquid, preferably a maximum of 20 kg / m3 of liquid, in particular a maximum of 10 kg / m3 of liquid, more particularly a maximum of 7 kg / m3 of liquid.

Preferably, the concentration of the degradable polymer during drilling is measured and, if desired, controlled so that the concentration remains within a desired range.

After drilling, a filter tube is preferably placed in the borehole, after which the well is developed. During the development, the degradable polymer is at least substantially removed. This is important to realize a suitable extraction capacity, to prevent subsequent blockage and / or to prevent later sand delivery.

The development by means of the invention offers in particular an advantage for creating a so-called natural overflow of a filter tube which is placed in the well.

In conventional (vertical) sources, a filter tube is usually provided with a diameter that is considerably smaller than the borehole (for example approximately two and a half times smaller). The filter tube is then covered with filter gravel. The filter gravel ensures that no sand enters the filter from the natural soil, or the filter gravel prevents sand delivery. This is called an artificial overflow.

By means of the invention it is surprisingly possible - also in soil with a relatively low permeability, as is typical in, for example, a Dutch soil - to manufacture a source with a filter tube surrounded by a natural overflow, without the risk of sand delivery and / or the risk of blockage of the filter tube becoming unacceptably high. With a natural tipping, a filter tube is not actually tipped with gravel, but a filtering layer is created around the filter tube by selectively removing part of the bottom around the filter tube.

To create a natural tipping, by means of the invention a filter tube (such as a winding wire filter) is usually placed in the borehole after which the well is developed. During development, the polymer and thus the plaster layer is broken down, whereby fine particles in the soil around the filter tube can be removed (washed away) from the soil and discharged through the borehole. A coarse fraction (coarse sand, gravel and the like) remains behind at least a part of the filter tube. This fraction forms a so-called natural overflow, which functions as a filter layer.

The filter tube is usually selected such that it is capable of at least substantially stopping a relatively coarse fraction (in particular with a particle size of at least 150 µm, more in particular of at least 300 µm).

For the well to develop well, the filter tube is usually chosen such that it allows a fine fraction (such as fine sand or a smaller fraction) to pass.

Very suitable is inter alia a winding wire filter with at least substantially a filter slit in the range of 0.1-0.4 mm, or a filter with a comparable permeability for soil particles. Such a filter gap is considerably smaller than the filter gap of filter tubes used in a conventional method in which the overflow is artificially realized.

A relatively high open surface of the filter tube is also of advantage. A filter with an open surface area of 11% or more, in particular up to about 20% or more, is particularly suitable. The upper limit is determined by practical considerations, such as sufficient rigidity of the filter tube.

Stainless steel is a suitable material for the filter tube. It offers sufficient strength and is sufficiently resistant to the action of the oxidizer.

The development involves the removal of degradable polymer (and optionally one or more other components of the drilling fluid). The drilling fluid can in part be removed in a conventional manner, for example by means of a physical development technique. Such a step can be carried out, for example, for at least one day, in particular for two to four days.

The development comprises a step in which at least a part of the polymer is broken down. This step preferably takes place after part of the drilling fluid has been removed in a conventional manner.

For a sufficient degree of degradation and / or a sufficient degradation rate, the degradable polymer in the well is generally contacted with a reagent in the presence of which the degradable polymer is degraded. A suitable reagent can be selected depending on the degradable polymer.

The reagent preferably comprises an oxidizer, more preferably a peroxide, particularly preferably hydrogen peroxide. Other particularly suitable oxidizers include bleach liquor and ozone. The use of a peroxide is particularly suitable for breaking down a polysaccharide. In addition, an oxidizer has an inhibitory effect on the growth of microorganisms, which is favorable for the biological quality of the water. The use of an oxidizer is therefore particularly suitable for the production of a well intended for the recovery of groundwater for the preparation of drinking water. The invention hereby makes it possible to use a polysaccharide in the drilling fluid, without a risk or at least 12 without an unacceptable risk that the polysaccharide contributes to excessive growth of microorganisms in the water, even if such a polysaccharide is a suitable food is for microorganisms.

Hydrogen peroxide in particular offers the particular advantage that it is a clean reagent (i.e. no undesirable substances are formed from the peroxide during reaction) and / or it inhibits the growth of microorganisms.

The reagent, such as the oxidizer, is preferably used in a stoichiometric excess with respect to the degradable polymer.

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Claims (14)

A method for manufacturing a horizontal water well, comprising - drilling a well in a water-carrying package in the presence of a drilling fluid comprising at least one oxidizable polysaccharide; and developing the well, comprising at least substantially removing the oxidizable polysaccharide wherein at least a portion of the polysaccharide is degraded in the presence of at least one oxidizer. The method according to claim 1, wherein the polysaccharide is a gum, preferably a gum from the group consisting of xanthan gum, guar gum and combinations thereof. 3. Method according to claim 1 or 2, wherein the concentration of the polysaccharide is in the range of 1 to 10 g / l, preferably of 2 to 7 g / l. A method according to any one of the preceding claims, wherein the oxidizer is used in a stoichiometric excess with respect to the oxidizable polysaccharide. 20 The method of any one of the preceding claims, wherein the oxidizer is selected from the group consisting of peroxides, chlorine bleach, ozone, and combinations thereof. The method of claim 5 wherein the oxidizer comprises water stop oxide. 1032588 ' Method according to one of the preceding claims, wherein after drilling a filter tube is placed in the well. 8. Method according to claim 7, wherein the filter tube is provided with a natural overflow. A method according to any one of the preceding claims, wherein the water carrying package has a water permeability of at most 100 m / day. 10 The method of claim 9, wherein the water carrying package has a water permeability of 10-80 m / day. 11. Water extraction well, obtainable by a method according to any of the preceding claims. A method for extracting groundwater, wherein groundwater is extracted from a well according to claim 11. The method of claim 12, wherein the groundwater is used for the preparation of potable water. 14. A method for storing water, wherein water is introduced into a water-carrying package via a well according to claim 11. 103258e