EP0384378B1 - Method and installation for the continuous disposal and processing of water-based, fluid and solid drilling residues - Google Patents

Description

The invention relates to a method and a plant for the continuous disposal and treatment of water-based liquid and solid drilling residues from clay-salt water and clay-fresh water rinses.

• 1. Ton-Frischwasser-Spülung
• 2. ton-Salzwasser-Spülung.

Water-based drilling fluids are used - in addition to the subordinate frequency of use of other types of fluids - for example when drilling oil and gas wells, as well as cavern and well drilling and drilling for investigation purposes in the mining industry. Due to the different geological formations that are pending to the final depth of a borehole, the water-based drilling fluid must be adapted to the respective geological requirements. This results in two main types of water-based drilling fluids, the

• 1. Fresh water rinse
• 2nd clay salt water rinse.

The composition (ingredients) of the two drilling fluid types depends on the operating conditions of each formation to be intersected, but is usually for
Type 1:
80 - 90% water
5 - 8% bentonite
0.5 - 2% organic substances (starch / CMC)
- 0.5% pH regulators (NaHCO₃ / NaCO₃ / NaOH)
8 - 12% of the (geological) formation drilled
Type 2:
70 - 85% water
5 - 6% bentonite / attapulgite
2 - 4% organic substances (starch / CMC + synthetic polymers)
0.05 - 0.1% pH regulators (as under 1 + Ca (OH) ₂ + Mg (OH) ₂
15 - 30% salts (NaCl / K11 / Mg²⁺ + Ca²⁺ mixed salts)
0 - 20% heavy spar (BaSO₄) or iron oxide with appropriate grinding fineness
Remaining bored (geological) formation
The substances contained in the water-based drilling fluids are e.g. T. dissolved, colloidally dissolved or hydrated and form a gelable suspension. Materials such as heavy spar or, to a lesser extent, iron oxide, to weigh drilling fluids down to higher specific weights used, are held or carried in suspension by the suspension.

The drilled formation materials partially dissolve in the drilling fluid or slowly accumulate as fine solids,
despite intensive efforts to provide them with appropriate
Devices as effectively as possible
solid or liquid drilling residues
to be removed from the drilling fluid. In the process of separating drilled solids from the drilling fluids - to the extent that they are included - parts of the weighting materials heavy spar and iron oxide are also separated (prior art).

The dirty water accumulating on drilling rigs is caused by precipitation and cleaning work. They are heavily influenced (contaminated) by the type of drilling fluid used and must be classified and disposed of accordingly.

WO-A-8 500 354 discloses a method and a device for separating the solid components from drilling muds. The method and the device work discontinuously in that the drilling mud is pumped from an interim storage facility into a settling tank, where it is mixed with pH adjustment agents and flocculants, with simultaneous stirring using an agitator. After the agitator has been switched off, the solids content is settled over a predetermined time. The supernatant sewage water is then pumped off and the settled solid is drawn off via a bottom outlet. The withdrawn solids portion is then subjected to an aftertreatment in order to achieve further concentration.

The object of the present invention is to provide a method and a plant for the continuous disposal and treatment of water-based liquid and solid drilling residues from clay-salt water and clay-fresh water rinses.

This object is achieved by the training according to claim 1.

A plant for performing the method is specified in claim 12 and a use of the processed solid in claim 16.

Advantageous and expedient developments of the method and the system are characterized in the assigned subclaims.

The present invention is particularly suitable for the continuous disposal and treatment of water-based liquid and solid drilling residues and also of waste water. Studies have shown that the processed solid is, for example, preferably suitable as a covering and lining material for landfills. Other areas of application include dyke construction, noise barriers, etc.

The invention will be explained below with reference to the accompanying drawings.

Fig. 1

schematisch eine Anlage zur Aufbereitung von salzhaltigem Schmutzwasser,

Fig. 2

ein Fließschema des Verfahrens zur Aufbereitung von salzhaltigem Schmutzwasser,

Fig. 3

ein Fließschema des Verfahrens zur Aufbereitung und Entsorgung flüssiger Bohrrückstände und

Fig. 4

ein Fließschema des Verfahrens zur Aufbereitung und Entsorgung von festen Bohrrückständen.

It shows:

Fig. 1

schematically a plant for the treatment of saline wastewater,

Fig. 2

a flow diagram of the process for the treatment of saline wastewater,

Fig. 3

a flow chart of the process for the preparation and disposal of liquid drilling residues and

Fig. 4

a flow diagram of the process for the preparation and disposal of solid drilling residues.

The disposal and treatment of the two types of drilling fluid (clay / fresh water and clay / salt water), their liquid and solid drilling residues and waste water are generally carried out in two separate, parallel process lines, namely for
Fresh clay water (T.-F.-W .-) - flushing and dirty water
also for
Clay salt water (T.-S.-W .-) - flushing and dirty water.

This means that the residual components from the T.-F.-W. rinse that are easy to dispose of are not mixed with those of the T.-S.-W. rinse. On the other hand, the different dissolved ingredients of both types of rinsing could lead to chemical / physical reactions that interfere with the process.
The principle of the method will be briefly explained below with reference to FIG. 1:
The aforementioned two separate, parallel-connected process lines each consist of high tanks as intermediate storage for wastewater for homogenization and preparation for separation into water and solids and high tanks as intermediate storage for liquid drilling residues or solid drilling residues of T.-F.- mixed with water to form sludge. W. rinse and the T. S. S. W. rinse for homogenization and preparation for separation into water and solid.

In Fig. 1, only a high tank 2 is shown as an intermediate storage for simplification.

The wastewater and liquid drilling residues prepared for separation are mixed in a ratio determined by their solids content and, mixed with inorganic and organic flocculants via the metering points D, transferred to a high tank 4 as a settling tank by means of pump B. This is where the separation of the flocculated suspensions into water and solid material begins. The flow rate of the water from bottom to top must not exceed the sinking rate of the solid particles.

In both process lines, the water is drawn off shortly under the tank cap via line K and either discharged into the sewage system of a larger capacity sewage plant and / or recirculated into the process flow for dilution purposes.

The solid is continuously drawn off via an inclined or funnel-like bottom 6 by means of a screw eccentric pump B 'and thickened using a centrifuge F.

Solids from the clay / fresh water process enter a membrane filter press and receive properties there that are required for landfill or building rubble disposal or for further use.

The solid from the clay-salt water process is prepared for further desalination with water supplied via a line H from the clay-fresh water process in a mixing unit G to an aqueous slurry. With the addition of flocculants via line D and H, the sludge is passed through an additional settling tank 8 and the separation process is repeated.

After renewed dewatering by means of a centrifuge F 'and the subsequent treatment in a membrane filter press, this solid is also salt-free and therefore landfillable (I) or can be further used in earthworks and foundation engineering.

The separated water is recirculated via a line C into the clay-salt water process.

• I. Die Aufbereitung und Entsorgung von Schmutzwasser
• II. Die Aufbereitung und Entsorgung flüssiger Bohrrückstände
• III. Die Aufbereitung und Entsorgung von festen Bohrrückständen

   Die Stufen I und II sind für Ton-Frischwasser- und für Ton-Salzwasser-Spülungen vorgesehen.In the following, the process is to be described in three stages in more detail. The three levels are:

• I. The treatment and disposal of dirty water
• II. The processing and disposal of liquid drilling residues
• III. The preparation and disposal of solid drilling residues

Levels I and II are intended for clay fresh water and clay salt water rinses.

Level III is used for the preparation and disposal of clay-salt water rinses and their salty drilling residues.

Stage I (see Fig. 2) Waste water disposal Example:

Water / flushing mixture with the following properties and ingredients: Mud weight Max. 1.17 kg / l Salinity Max. 250.00 g / l Solid Max. 5.00% vol.

The solid may only consist of drilled formation or irrigation material. Heavy metal salts or compounds, such as those used for the production of heavy annular space liquids, e.g. B. CaBr₂, are not among the permitted ingredients.

• 1. Schnelle Entladung eingehender Fahrzeuge
• 2. Auffangen der stoßweisen Fahrzeugentladung über ein ausreichendes Puffervolumen
• 3. Entfernung von groben Verunreinigungen, die nicht zu den definierten Feststoffen gehören und zu Störungen in der Anlage führen könnten
• 4. Homogenisierung und Vorbereitung des Feststoff-Flüssigkeit-Trennungs-Prozesses durch Einstellen des pH-Wertes auf 7 bis 6,8.

The above-mentioned interim storage of waste water takes place for the following reasons:

• 1. Fast unloading of incoming vehicles
• 2. Collection of intermittent vehicle unloading over a sufficient buffer volume
• 3. Removal of coarse impurities that do not belong to the defined solids and could lead to faults in the system
• 4. Homogenization and preparation of the solid-liquid separation process by adjusting the pH to 7 to 6.8.

In order to ensure homogenization and to avoid simultaneous sedimentation of the solids in the intermediate storage 10 (mixing tank), a circulation (pump B, line C) is provided, which also takes over the further transport of the dirty water. Test taps are provided on the tanks for control purposes. The performance of the pump unit B depends on the capacity of the storage facility.

For 150 m³ intermediate storage volume, a circulation and transport volume of approx. 10 m³ / h each, that is a total output of approx. 20 m³ / h, is required. The quantity distribution is based on demand, i. H. adapted to the incoming amounts of dirty water.

The pH value adjustment of the dirty water in the interim storage facility (not shown in more detail in FIG. 2) serves to destabilize the suspension consisting of minerals and organic substances. Acetic or hydrochloric acid is used, which is expediently metered by means of a peristaltic pump.

From the interim storage facility 10, the pH-adjusted waste water arrives at a continuous pumping rate of 5 - 10 m³ / h with the addition of inorganic or organic flocculants via the connection D into a further high tank 12, which functions as a settling tank. The size of the tank 12 is determined by the throughput capacity required. Approx. 1/3 of the tank volume is used for sedimentation and approx. 2/3 for the separation of water and solid.

The inlet nozzle in the settling tank is to be installed at approx. 1/3 of the total height above the floor, cf. also Fig. 1. It leads in the tank into a horizontal pipe 14 provided with holes (see Fig. 1), which ensures a uniform distribution of the water / solid mixture over the entire tank surface. The holes in the pipe are directed upwards and downwards to take into account the natural flow direction of water and solids and to prevent blockages in the pipe.

The rate of buoyancy of the water above the distributor pipe 14 must not exceed the rate of descent of the solid particles. To check the separation process, test taps are attached to the tank at intervals of 1.5 m (not shown). The clarified water is drawn off below the tank cap via line K and, if necessary, cleaned using a vacuum filter before it is discharged into the sewage system of a municipal wastewater treatment plant with a larger capacity.

A recirculation option to the interim storage facility is provided (see line K) and is very important for the subsequent processing stages.

The solids in the form of sludge come to rest in the lower third of the tank and sediment on the sloping or funnel-like bottom 6 of the tank (cf. FIG. 1). Sample taps are also provided for this part to control the sedimentation process (not shown).

At the lowest point of the tank bottom, the sludge is continuously removed with a screw eccentric pump B ′, for example with a volume of 1 to 3 m³ / h. The removed pre-dewatered sludge from the T.-F.-W. process is further dewatered in membrane filter presses 15 (line E) and then goes to landfill or further use. The sludge from the T. S. S. W. process is examined for salinity.

Depending on the result of the investigation, the solids also reach the landfill or further use or an additional desalination process via the membrane filter press.

For the desalination process, the solid is first fed to a centrifuge F. Depending on the nature, the liquid from the centrifuge returns to the interim storage facility or the sewage system via recirculation. The solid from the centrifuge is worked up again with the water (line H) from the T.-F.-W. process to form an aqueous slurry in the mixing unit G, provided with flocculants (lines H and D) and a new settling process in one subjected to further settling tank 16 with simultaneous dilution of the salt content. Further dewatering via a centrifuge and membrane filter press leads to solid materials (I) that can be landfilled or reused.

Stage II (see Fig. 3) Disposal of liquid drilling residues from clay-salt water and clay-fresh water rinses

Liquid drilling residues are hydrocyclone deposits, as u. a. in solids control of drilling fluids, which can also be non-reusable T. S. W. W. They consist of 75 - 80% drilling fluid and 20 - 25% drilled formation. Due to the chemical / physical properties, these drilling residues can only be processed into drilling fluids with great economic effort. Crucial for this is the accumulation of solids from drilled formation in the range of 1 - 40 µ and the use of expensive chemicals.

The high solid content is crucial for disposal. The permitted ingredients include, as under Level I mentioned earlier, just drilled formation and mud material. Heavy metal salt or salt such as those used for the production of heavy annular space liquids, including CaBr2, are not included.

• 1. Schnelle Entladung eingehender Fahrzeuge
• 2. Auffangen der stoßweisen Fahrzeugentladung über ein ausreichendes Puffervolumen
• 3. Ölhaltige sowie nichtölhaltige flüssige Bohrrückstände werden aus Gründen eventueller unterschiedlicher Entsorgung in zwei Hochtanks 18 und 20 getrennt gelagert
• 4. Homogenisierung und Vorbereitung des Trennungs-Prozesses in Feststoff und Flüssigkeit durch Einstellen des pH-Wertes auf etwa 7.

The liquid drilling residues are temporarily stored for the following reasons:

• 1. Fast unloading of incoming vehicles
• 2. Collection of intermittent vehicle unloading over a sufficient buffer volume
• 3. Oil-containing and non-oil-containing liquid drilling residues are stored separately in two high tanks 18 and 20 for reasons of possible different disposal
• 4. Homogenization and preparation of the separation process in solid and liquid by adjusting the pH to about 7.

In order to ensure homogenization and at the same time to avoid sedimentation of the solids in the interim storage facility, the liquid drilling residues are circulated or pumped around. A screw eccentric pump B with a conveying capacity of approx. 20 m³ / h is expediently used. During the circulation, the solid / liquid separation process is prepared by adjusting the pH value to approx. 7. The flocculation limit of the fine, hydrated clay particles and the stability limit of the acetate bonds of the organic substances lie in this pH value range. The pH value must therefore not fall below 6.5. To adjust the pH value, a metering pump (peristaltic pump) of sufficient capacity for appropriate acid (HCl / CH₃-COOH) is provided. The bigger the intermediate storage, i.e. the buffer volume, the lower the risk of acid overdosing, and thus the susceptibility to failure of the entire system is reduced.

The pump unit B for circulating the intermediate storage also takes over the transport of the liquid drilling residues prepared for the separation into a settling (high) tank 22. The equipment of this tank has already been described for stage I (FIG. 2).

Dilution is initiated before the liquid drilling residues enter sedimentation tank 22 for sedimentation. The high solids content, which fluctuates despite homogenization, does not allow direct flocculation. Laboratory tests have shown a mushy to pasty substance. The liquid drilling residues are therefore first diluted with dirty water. This is done by introducing the prepared liquid drilling residues into the transfer line of the dirty water from the dirty water intermediate storage 24 into a settling tank 26. The amount of flocculant is added to the dirty water via the connection D in such a way that with a mixture ratio of five parts of dirty water and one part of liquid drilling residues Flocculation sets in. To intensify the mixing process, a mixing tube can be installed after combining both liquids. The mixing tube must not delay the formation of flakes or destroy existing flakes.

The flocculated mixture reaches the settling tank 26 via a perforated distributor pipe (see pipe 14 in FIG. 1). If the mixing ratio of dirty water / liquid drilling residues is not entirely correct at times, the tank volume ensures further dilution and better sedimentation of the solids. This buffer system keeps the system susceptible to malfunctions. The throughput capacity per day depends on the volume of the sedimentation tank, but should be two to four times its 2/3 volume.

The water overflowing from the settling tanks 22 and 26, freed from solids, is recirculated in the clay-salt water line, as described in stage I, into the dirty water intermediate storage (line K) or the excess, if necessary, via vacuum filter to the sewage system (line K ) submitted.

The sedimented solid from the sedimentation tanks is continuously withdrawn according to stage I by means of a screw eccentric pump B 'and led to the drainage through a centrifuge F and a chamber filter press (E and I). The separated liquid passes through the recirculation system (line C 'and C) into the dirty water intermediate storage 24th

The solid is examined for its residual salt content in the eluate and, if necessary, subjected to desalination. For this purpose, it is treated with the water (line H) from the clay / fresh water process in a mixing unit G to form an aqueous slurry. The salt content of the solid is diluted according to the amount of water and its salt content. Another settling and dewatering process corresponding to stage I with a further settling tank 28 and a membrane filter press results in landfillable or reusable material. The water reaches the dirty water intermediate storage 24 via the recirculation system.

The clarified water from the clay-fresh water process is, as already described, required to dilute the salt content in the solid from the T. S. S. W. process, or it is in the dirty water intermediate storage of the clay-fresh water process line for further dilution operations on liquid drilling residues.

After dewatering, the solid matter from the clay / fresh water process reaches the intended landfill using a centrifuge and membrane filter press or is sent for further use. The separated water will recirculated to the dirty water interim storage facility of the T.-F.-W. process line.

The water intended for recirculation into the intermediate wastewater storage facility is collected in two 10 - 15 m³ tanks and either pumped into the intermediate storage facility with a level-controlled centrifugal pump or used for use in a subsequent stage III to liquefy solid drilling residues from clay-salt water rinsing.

Oil-containing, liquid drilling residues are stored separately from the process strands described and, after homogenization, checked for solids and oil content and first centrifuged. The oily solid goes to the hazardous waste landfill or for incineration.

The centrate, also examined for solids and oil content, is - depending on the result - added to the process described above in larger or smaller quantities or also disposed of as special waste.

If the solids concentration is low, the salt concentration is low and the protective colloid content is low, the settling tanks are not used and the liquid and diluted drilling residues are fed directly to the drainage using a centrifuge F or chamber filter press (E and I). For this purpose, the settling tanks bridging bypass lines (BP) can be provided, as shown in dashed lines in FIG. 3.

Stage III (see Fig. 4) Disposal of solid drilling residues from clay-salt water rinses

Solid drilling residues are mainly drilled geological formations and drilling fluids adhering to them, which are extracted from the drilling location using shaking sieves Drilling fluid is removed. The ratio is approx. 75 - 85% formation to 25 - 15% drilling fluid. In addition to hydrocyclones that generate liquid drilling residues, see level II, centrifuges are also used to control the formation solids in drilling fluids. Like hydrocyclones, centrifuges work on the principle of centrifugal forces, only much more effectively than hydrocyclones. This is what happens another category of solid drilling residues, the solid ejection of centrifuges. The ratio of drilled formation to mud is similar to that of the screened material, but of a much finer consistency.

Solid drilling residues may therefore only consist of drilled geological formation and drilling material, as is required for the production of drilling fluids (see page 1).

Other wastes, such as paper, wood or cleaning rags, as they occur at drilling locations, are not among the defined substances to be disposed of.

The defined, solid drilling residues to be disposed of are strongly influenced by the type of mud from which they have been removed.

Before these solid drilling residues are deposited, the salt is removed from them if necessary. To do this, proceed as follows:
The incoming tipping vehicles (trucks) loaded with dredging drilling residue approach the mixing units G ′ with a minimum volume of 25 m³. The cargo is taken up in the mixing units with recirculated water (line K) from the recirculation systems and diluted to a state that is easy to pump. After completion of this process, the sludge produced is transferred to the intermediate storage 18, 20 for liquid drilling residues of the respective processing line, for example by means of a screw eccentric pump B '.

In the intermediate storage, homogenization is carried out in accordance with stages I and II and the pH is adjusted so that reference should be made to the description there.

The recirculation system is of great importance for the efficiency of the entire system. The importance is to always have enough water available for the dilution processes in stages II and III without the need for dilution water must be taken from other sources (e.g. wells, receiving water, rivers).

Claims (16)

1. A process for the continuous disposal and treatment of water-based, liquid and solid boring residue from clay-salt water and clay-fresh water rinsing operations having the following process steps:

   1. intermediate storage and homogenisation of the water-based, liquid and solid boring residue,

   2. destabilisation of the water-based, liquid and solid boring residue containing minerals and organic substances by adjusting the pH value,

   3. circulating the water-based, liquid and solid boring residue, the pH value of which is adjusted, in order to prevent sedimentation,

   4. dilution of the water-based, liquid and solid boring residue to lower the salt content of the boring residue,

   5. treatment of the water-based, liquid and solid boring residue pumped from the intermediate stores with flocculant by the metered addition of the flocculant during the transfer from the intermediate store to a device for the flocculation and settling of the solids content,

   6. continuous flocculation and settling of the solids contents of the water-based, liquid and solid boring residue, by the liquid boring residue treated with flocculant is continuously pumped into a settling tank, whereby the buoyancy velocity of the treated water is adjusted to be less than the sinking velocity of the solids content,

   7. continuous drawing off of the sedimented solids for further use or to the dump, if necessary after prior concentration,

   8. continuous recirculation of the water for dilution purposes into the process (into the intermediate stores) and

   9. continuous delivery of the sewage water to a sewage treatment plant, when the salt content of the recirculated water is equal to the salt content of the treated water of the solid.
2. A process according to Claim 1,
   characterised in that the 6th process step is omitted in the event of a low solids concentration, low salt concentration and low content of protective colloids.
3. A process according to Claim 1 or 2,
   characterised in that with solids from a clay-salt water process the following further process steps are provided before process step 8 with a residual salt content lying above a value which can be specified:

   6.1 treatment with water to form an aqueous sludge for the demineralisation of the solids,

   6.2 treatment of the sludge with flocculants,

   6.3 flocculation and settling of the solids content.
4. A process according to Claim 1,
   characterised in that dilution is performed with dirty water.
5. A process according to Claim 4,
   characterised in that dilution is performed in the ratio of five parts dirty water to one part liquid boring residue.
6. A process according to Claim 5,
   characterised in that the flocculant is added to the diluting agent (dirty water).
7. A process according to Claim 1,
   characterised in that for the disposal of solid boring residue (in particular from clay-salt water rinsing operations) this boring residue is mixed before intermediate storage with recirculated water to form an easily pumpable sludge.
8. A process according to Claim 1 or 2,
   characterised in that the pH value is set at roughly 7.
9. A process according to Claim 1 or 8,
   characterised in that the pH value adjustment is performed by means of hydrochloric acid or acetic acid.
10. A process according to Claim 3,
    characterised in that the treatment to form the aqueous sludge is performed with water from the clay-fresh water process.
11. A process according to one of the preceding Claims,
    characterised in that the oil-saturated liquid boring residue is disposed separately from the other boring residue.
12. A plant for performing the process according to one of the preceding Claims with high tanks as the intermediate storage means (2, 10, 18, 20, 24) for housing the water-based, liquid and solid boring residue, to which are connected appliances for the metered addition of acid for the purpose of adjusting the pH value of the intermediately-stored, water-based, liquid and solid boring residue, and lines (C) for diluting the boring residue and also a circulating device (B), and which are connected to a single-stage or multi-stage disposed settling tanks (4, 6, 12, 22, 26), through which there is a continuous flow, via discharge lines, to which lines (D) for the metered addition of flocculant are connected, whereby in the settling tanks is disposed a horizontal distribution pipe (14) having upwardly and downwardly directed holes, which is connected to an inlet connections for the water/solid mixture, and
    the settling tanks, through which there is a continuous flow, comprise outlet connections in the base region for the sedimented solids of the water-based, liquid and solid boring residue and delivery connections in the upper region for treated water, to which lines (C) are connected for the return of the water into the intermediate tanks for the dilution of the boring residue.
13. A plant according to Claim 12,
    characterised in that the pumping rate for the water/solids mixture is adjusted so that the buoyancy velocity of the water is less than the sinking velocity of the solids particles.
14. A plant according to Claim 12,
    characterised in that with a low solids concentration, low salt concentration and low content of protective colloids, the settling tanks can be bypassed by bypass lines (BP), which can be connected to the discharge lines and to the recirculating lines (C).
15. A plant according to Claim 12,
    characterised in that to the settling tanks are connected appliances for the concentration of the discharged solids contents.
16. Use of the treated solids produced by the process and the plant according to the previous Claims as a material in earthwork and foundation engineering.

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