DE3017122A1 - DRILLING PROCESS - Google Patents

Description

(G 102) G 80/27

Hm / bd 2.5.1980 10

Drilling method

The invention relates to a drilling method in which a flushing medium is passed through the borehole in heat exchange is brought with the rock and / or the drilling tool and derived from the borehole.

In addition to the choice of a suitable drilling method, when developing and exploiting raw material deposits, For example crude oil or natural gas deposits, it is essential to secure the borehole when sinking. The backup is used among other things, a destruction of the borehole by the mechanical forces of the mountains surrounding the borehole to prevent, i.e. to protect the borehole from collapse and collapse. According to traditional methods therefore a borehole was drilled in stages and each stage was secured. If a step is bored, it is bared, i.e. steel pipes are lowered into the borehole and the space between the steel pipes and the borehole wall filled in with cement. The pipe run of the following stage is built through the previous one. If the rock is not sufficiently stable before a step is reached, the borehole wall must

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be supported by other means until piping.

In conventional procedures, this protection is provided by flushing liquids achieved by a liquid whose density can be increased by adding suitable fillers, is directed into the borehole. Drilling with liquid and possibly weighted fluids entails, that the hydraulic "column, which should only press against the open borehole walls, with all its load also rests on the bottom of the borehole and energetically counteracts the mechanical loosening process there. The chiseling performance decreases as the mud weight increases. The usual heavy flushing therefore work the dissolving process at the bottom of the borehole. Together with the flushing pressure, which increases with increasing depth, the drilling resistance increases. pending and the drilling progress decreases accordingly. However, a slower drilling progress is synonymous with higher drilling costs. At great depths, the hydraulic ones that occur in long open mountain stretches are also hydraulic Imbalances are another cost-increasing factor to consider. Taking these imbalances into account calls for more intermediate tubing and therefore a large initial diameter for the first stage drill bit. The consequences of this measure are expensive piping and high flushing costs, so that this also reduces the borehole costs noticeably increase.

The invention is based on the object of a method to develop with which a well can be sunk quickly and at low cost.

This object is achieved according to the invention in that the flushing medium is cooled to a temperature below the temperature before it is introduced into the borehole, which, in the case of a circulating flushing medium, after exiting the borehole during heat exchange with the Environment.

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In contrast to conventional methods to cool me circulating flushing for days in the natural heat exchange with eg air at some 10 to 20 ⁰ C, the temperature of the flushing medium is inventively lowered below this temperature (cold rinse). This is an advantage, since all sediments and rocks of the overburden behave in such a way that they become more dimensionally stable and therefore more statically stable with falling temperature. Therefore, if sufficient heat is extracted from the rock by cold flushing according to the proposed method, a more stable borehole is the result. Since open borehole stretches are more or less stabilized in this way, the hydraulic pressure exerted by the mud on the borehole wall can be reduced. This means that conventional heavy flushes can be replaced by specifically lighter flushes. The use of a mud with a low specific weight, however, relieves the load on the bottom of the drill hole and therefore directly results in better drilling performance.

Another obstacle to work at greater depths for conventional methods is the increasing temperature. With gradients between 25 and 50 K / km, there are approx. 520 to 770 K at a depth of 10 km. By a cold rinse there is a more favorable temperature level for the The drilling tool and the drilling assembly. In particular, can the temperature can be lowered to a value at which the drilling components do not suffer any damage beyond normal wear and tear in continuous operation. One Search for materials that are resistant to the temperatures prevailing at great depths, as well as their ' There is no need for testing.

According to an advantageous embodiment of the method according to the invention, the flushing medium is down to below 0 ^° C

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chilled. In this way, an open mountain stretch can are cooled to such an extent that the water of the mountain-moist sediments of the mountains surrounding the borehole freezes. In the process, a stable frozen body is formed that is impermeable to water and gives the mountains sufficient strength confers. The area of the borehole that has not yet been secured by pipes can therefore be temporarily supported and non-stable mountains are converted into stable mountains through the formation and maintenance of frozen bodies will.

Frozen mountain moisture significantly increases the stability of the mountain compared to cooling without the formation of frost. The more stable the rock surrounding the borehole, the lower the specific weight of the flushing medium can be can be selected and the greater the drilling progress - because of the increasing relief of the borehole bottom.

According to a further feature of the inventive concept, the flushing medium is therefore particularly advantageously gaseous. A The main advantage of this procedure is that the previously described inhibiting effect of a column of liquid is omitted above the bottom of the borehole. A gas is supplied to the borehole, which practically falls on the bottom of the borehole does not exert any pressure. As a result, it can be compared to heavy irrigation a significantly higher drilling progress can be achieved and a reduction in drilling costs can be achieved. Without the supporting pressure on the borehole wall, all problems that arise during heavy flushing are eliminated result from hydraulic imbalances in longer, open drilling runs. When using heavy irrigation up to now the case could arise that a certain flushing pressure had to be maintained at a depth, which would have been too big at any other depth since it is too would have led to a breaking up of the mountains. In such

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In some situations, an additional pipe run was necessary. Since according to the invention no pressure is exerted on the borehole wall additional pipe runs are no longer required. This reduces piping and flushing costs.

Another advantage of the method according to the invention results from the intensive cooling of the drill and drilling in a cold environment: Due to the lower material wear, the tool life is longer than in the otherwise increasingly warm environment with increasing depth. This means that a drilling tool is technically effective for longer and can be used economically. Better use of materials and fewer round trips, i.e. The consequences are installation and removal of the drill set with changing the drilling tool.

In the case of gaseous flushing, it is essential that the flushing medium is sufficiently deeply cooled so that it is in an open one Mountain stretch quickly creates a load-bearing mantle. The speed of formation and also the carrying capacity of the The mountain mantle depends, among other things, on the thermal properties of the mountain, e.g. on the thermal conductivity, the heat capacity or the temperature gradient. The speed of formation in turn determines the speed of drilling fixed. It is therefore of advantage if a formation speed which is as high as possible can be achieved.

For this purpose, in an advantageous embodiment of the method according to the invention, a liquefied rinsing medium is used Gas used in heat exchange with the mountains surrounding the borehole and / or the drilling tool at least partially evaporated.

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Ι Especially at great depths or hot formations this configuration is expedient. The mountains can also have a heat corresponding to the evaporation heat of the liquefied gas Amount of heat are withdrawn, so that the mountains and the moisture of the penetrated layers particularly quickly is cooled or made to freeze. A stable body of frost around the borehole is correspondingly fast created. If a liquefied gas is supplied to the unsecured area of the borehole, considerably more heat can be generated dissipated and - for example the drilling tool - better cooled.

In this case it is not necessary and also not under all circumstances to realize that the liquefied gas is completely evaporates. It is only essential that the flush brings the necessary amount of cold on site, the mountains there withdraws enough heat and is then still able to bring both the cuttings to the surface and the appropriate ones Cool condition in the already drilled stretches to obtain.

According to another feature of the method according to the invention, the cooled flushing medium is advantageously in the area the bottom of the borehole. The medium cooling the rock reaches the bottom of the borehole at a very low temperature. This promotes thorough cooling of the drilling tool and the rock in the drill bottom area. Directs If, in particular, a liquefied gas is introduced into the area of the bottom of the borehole, the fresh bottom of the borehole is intensively quenched and can easily be removed by a mechanically attacking drilling tool. The one in thermal contact Steam formed with the rock pulls the cuttings away from the bottom and flows through the annular space between the drilling tools and borehole wall exposed. As a result of the volume increase associated with the phase change

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a high flow velocity. On the way between the bottom of the borehole and the surface of the earth, the steam takes further Heat and thus preserves the already formed parts of the

Frost jacket upright until piping is installed. 5

In a variant of the method according to the invention the flushing medium via its own line, which can be thermally insulated, into the area of the open mountain range of the Borehole. The end of the line can advantageously be at any height that can be adjusted from above ground be held so that the flushing medium can be supplied to each area of the borehole.

According to a further embodiment of the inventive concept it is particularly useful when the flushing medium, e.g. in a rotary drilling process, through a flow cross-section within the rod, through which the drilling tool is rotated by a drive located above the surface, and through the drilling tool is directed to the bottom of the borehole and returned outside the string. There is no Necessity to provide another line for the supply of the cooling flushing medium. Especially when using liquefied, low-boiling gases, it is advantageous the linkage against heat input at least partially

to isolate.

A particularly effective cooling of the drilling tool and an even distribution of the cooling flushing medium in the borehole is achieved when the gas according to an advantageous embodiment of the method according to the invention is passed through several openings in the drilling tool in the area of the borehole bottom.

Due to the physical properties and the relative low cost nitrogen and carbon dioxide are suitable

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especially for use in the process according to the invention. It should be noted that carbon dioxide must be kept under pressure, and therefore a drill pipe or a supply line with pressure maintenance is required.

In summary, it can be stated that the method according to the invention enables the gross drilling step to be increased. To determine the greatest possible drilling progress it is important to optimize the values for the specific weight and the temperature of the cold rinse. The setting both dictate the mountain range (mainly due to the inherent stability and speed of formation of the supporting shell) and the temperature behavior of the drilling system (primarily drill string and fluids). The range of the invention The methods of irrigation that are involved therefore extend from irrigation, the weight of which is significantly lower than that of conventional rinsing and whose temperature is greatly reduced, up to rinsing with moderate reduced temperatures and correspondingly high weight, but always smaller than that of conventional flushing is.

If a rinse with a greatly reduced temperature is used, it may, as described, be underweight in comparison to previous rinses. Such rinses only contribute part of the necessary supporting forces. In addition, the rock is self-supporting with the help of the cooled borehole jacket. Two things are self-evident here:
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a) Each cold rinse must take place at the working temperature (= circulation temperature) Have the best possible flushing values, but may have certain at rest temperatures Do not lose minimum properties. Cold, liquid rinses, for example, heat up if the machine is not used for a long period of time;

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in borderline cases up to the resting temperature of the mountains.

Then, above all, they must not "break", ie not lose the incorporated gel strength, because otherwise the cuttings in the mud will sediment and block the drilling assembly. Aqueous cold rinses should be conditioned so that it (e.g., about 8 d) remain at least for a limited time to 200 ⁰ C temperature resistant.

b.) the combined stability must at least take place during scheduled breaks (chisel change, measurements, pipe installation and cementation) can be retained or retained.

The advantages of this process allow a significant reduction in the costs of deep and over-deep drilling. Of the Use of the proposed method should be of particular interest in the search for (crude oil or) natural gas. Because in many countries, e.g. in the Federal Republic of Germany, the overburden down to a depth of around 3,000 m is now so thorough it has been researched that there are hardly any noteworthy finds to be expected there, must be more and more deeply and deeply Excessive areas are drilled if the supply is kept at the current level or even expanded target. Another area of application is likely to be in the extraction of geothermal energy. If this alternative is the energy balance should noticeably relieve pressure, outcrops must be driven in deep hot rock, as the few shallow occurrences or thermal springs do not make a significant contribution. The drilling costs of conventional methods would however, make such projects unprofitable from the outset.

In the following, an exemplary embodiment of a procedure according to the invention is intended to be based on a schematic sketch are described:

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Show it:

FIG. 1 shows a device operating according to the rotary drilling method, which is suitable for carrying out the method according to the invention;

Figure 2 some temperature fields.

According to FIG. 1, a drilling tool is used via a rod 3 and a drill collar 4 is driven by a drive, not shown, via a turntable 5, a borehole 1 sunk. Also not shown a large part of the derrick 6 as well as devices for removing the drill string. A preventer is installed at the wellhead mounted as soon as the first pipe run 7, the anchor pipe run, is backfilled with cement 9. In the sketch is another tube trip 10 is shown, which is also with Cement is backfilled and sunk through the 'the third stage will. In the exemplary embodiment, the borehole wall is to be cooled with the aid of liquid nitrogen and in the surrounding area Mountains, i.e. in the area 17 around the borehole, the an annular one extends from the lower end 20 in the cementation of the second pipe run 10 to the bottom of the borehole 21 Frost bodies are formed (dashed area). For this purpose, liquid nitrogen is made from a Storage tank 11, which is surrounded by thermal insulation 12 and set up above ground, via a valve 13 and a removal line 14 removed and fed to a transfer head 15. The transfer head has the task of nitrogen in liquid form in the double-walled Bohrcrestänge 3, the designed as a vacuum-insulated liquid nitrogen downpipe should be to initiate. Is the heat content of the. Dissipated from the supply system, liquid nitrogen arrives via several openings in the drilling tool 2 to the borehole bottom 21 or to the one adjacent to the borehole bottom

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Borehole wall 1. In direct thermal contact with the surrounding In the mountains, the liquid nitrogen evaporates and, even at high temperatures, brings the water content to the mountains the sediments to freeze. The vaporized nitrogen flows at high speed into the space between the Collar-s 4 and the borehole wall 1, with drill cuttings is torn away from the bottom of the borehole and carried up by the vaporous nitrogen. Eliminates in the further course the vaporous but very cold nitrogen to the mountains above the bottom of the borehole 21, in which already a frozen body has been formed, heat and thus maintains the already formed frozen body. Afterward The nitrogen flows through the area of the two pipe runs and passes through a discharge line 18 into the atmosphere. Carried cuttings are collected in pit 19. Once the desired depth of the third Level is reached, the cooling can be stopped and the third pipe run can be introduced and cemented. The individual steps in the process according to the invention are significantly longer than in conventional processes. Therefore, a borehole of a certain depth can be sunk with fewer pipe runs using the proposed method will.

In the case of cold flushing, it is advantageous to use local drives. Therefore, in the exemplary embodiment in FIG the arrangement of a local drive 22 is indicated. Such drives are on the actual drill string (= Drill collar + chisel), and only this ^ part is set in rotation. The drill pipe above rests and mainly only has to absorb the back torque. The turntable is not omitted because of the experience teaches that it is occasionally useful to use the linkage

to move slowly with.
35

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In Figure 1 are some temperature fields of circulating rinses at a depth of up to 10 km and a temperature gradient of 37 ° / km. The following procedures are shown in detail:

1. Low rinsing rates and of course re-cooling for days.

2 .. High flush rates and natural recooling over days.

3. Great Purge rates and artificial re-cooling for days at 10 ⁰ C inlet temperature.

4. Large flushing rates and artificial recooling over days to -100 ⁰ C inlet temperature.

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Claims (6)

(G 102). ■ G 80/27 Hm / bd 2.5.1980 10 patent claims 1. Drilling method in which a flushing medium passes through the borehole conducted, brought into heat exchange with the rock and / or the drilling tool and diverted from the borehole is, characterized in that the flushing medium before being introduced into the borehole to a temperature is cooled below the temperature that occurs with a circulating flushing medium after the outlet adjusts from the borehole during heat exchange with the environment. 2. The method according to claim 1, characterized in that the flushing medium is cooled ^{to a temperature below 0 0 C.} · 3. The method according to any one of claims 1 or 2, characterized in that the flushing medium is gaseous. 4. The method according to any one of claims 1 to 3, characterized characterized in that a liquefied rinsing medium Gas is used, which is in heat exchange with the mountains surrounding the borehole and / or the drilling tool at least partially evaporated. Shape. 5729 7.7B 130045 / 0-457 1 5. The method according to claim 4, characterized in that the liquefied gas is nitrogen or carbon dioxide is used. 5 6. The method according to any one of claims 1 to 5, characterized in that that the flushing medium is passed into the uncased area of the borehole via its own line will. Shape. 5729 7.78 130045/0457