NL8204793A - METHOD AND APPARATUS FOR TREATING OIL-CONTAINING DRILL GRILL. - Google Patents

Description

P & C ** * j> W 2909-606 fed. / DB / WV?

Short designation: Method and device for treating oil-containing drill cuttings.

The invention relates to a device and method for the treatment of oil-containing drill cuttings in the hearing area before it is discharged and in particular to a device and method for treating this drill cuttings in such a way that the treated cuttings can be exposed to minimal ecological risks. be thrown away.

In rotary drilling, a fluid, commonly referred to as mud, is circulated from a surface storage area along the drill pipe down through openings 10 in the drill bit and back within the borehole to the surface. This backwash carries the drill cuttings from the bottom of the borehole and, along with the included drill cuttings, is fed to a "slate shaker" before it is returned to the storage area. The shaker, normally located above the mud storage area, is essentially a screen used to separate the drill cuttings and the mud from the mud. Gravity falls through the sieve by gravity and the drill cuttings move over the end of the sieve.

20 The dumping of this separated grit is sometimes a problem. For example, when using a drilling fluid system with an oil based mud that covers the grit with undesirable pollutants, the grit cannot be deposited directly without the risk of contaminating the area around the hearing site. While dumping the contaminated drill cuttings is difficult in offshore drilling, it can also be a major problem in onshore drilling where environmental concerns prevent normal dumping of the untreated cuttings.

There are two general techniques for treating this contaminated grit to make it ecologically acceptable. The grit must either be transported to a landfill or it must be treated on-site to remove the pollutants before dumping.

The additional costs due to the transport of the grit from a hearing place at sea are large and therefore form a serious drawback for the general commercial application of this 820 4 79 3. t - 2 technique. Furthermore, transporting the cruise to the coast for dumping may be impractical in areas of bad weather and rough seas. It is therefore clear that the treatment and subsequent dumping of the drilling crust is preferable, in particular drilling at sea, directly at the hearing site.

Various methods have been proposed for treating contaminated cruises on site. One of these is burning the oil with high-intensity lamps of the cruise. However, Fit poses problems (i.e., potential fire hazard from exposing the lamps and the difficulty of exposing all grit to the lamps at the same rate) making this method unusable in most cases.

Another method involves washing the grit 15 with a detergent to remove the contaminants, separating the contaminants from the washing solution and pouring the clean grit into the water. An example of this method is described in U.S. Pat. No. 3,683,781.

A further method is known from US patent 4,209,381, according to which the contaminated cruise is separated from the drilling mud and fed to a heating unit in which it is sprayed with interference to remove the oil from the grit by evaporative distillation. The distilled oil and the spent steam are fed to a refrigeration unit where they are condensed before being suspended on a water-separator.

In yet another method, according to U.S. 3Q Patent 4,242,146, the drilling crust is thoroughly mixed with an oil absorbent. material, for example clay. When the grit is originally quite large in size, it is ground for mixing with the oil absorbent material so that some of the contaminating oil is absorbed into the extra solid oil absorbent material of the cruis itself which is released by grinding. The ground and blended grit is then compressed into spheres or briquettes before being crushed to ensure

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1 · - 3 - that the grit safely sinks to the bottom of the water into which it is being dumped.

In one aspect, the present invention includes an apparatus for treating oil-contaminated drill cuttings generated during drilling for oil, circulating a drilling fluid to remove the drill cuttings from the well being drilled, which method is characterized by a) a shaker for separating the drill cuttings from the drilling fluid, b) a storage tank for collecting the drill cuttings, c) a grinder for increasing the surface of the drill cuttings to obtain extra solid oil absorbing material , and d) a mixer for increasing the absorption of free oil in the extra solid oil absorbent material released by the enlarged surface of the ground grit.

In a preferred embodiment, a controlled amount of additional solid oil absorbent material is added to the storage tank and a stirrer in this tank mixes the drill cuttings with the added solid oil absorbent material. A conveyor transports the mixed drill cuttings to the grinder. Part of the mixed drill cuttings are returned to the storage tank to enhance the mixing process. The flow rate of the mixed drill cuttings from the storage tank to the grinder is controlled such that the pour rate of the drill cuttings is not less than the sum of the rate at which the drill cuttings are produced plus the rate at which the oil absorbing material is added.

In a further embodiment, the conveyor between the storage tank and the grinding device is a mixing conveyor. Extra solid oil absorbent material can be added to the mixing conveyor whereby the drill cuttings are mixed with the added solid oil absorbent material as it is transported from the storage tank to the grinder. ~

In yet another embodiment, a compressing machine compresses the ground grit into individual masses of sufficient density to sink in water. A sieve separates from the compressed grit the fine material which does not have the desired properties to be poured into water. The fine material, separated from the compacted drill cuttings, is recycled through at least part of the lever handle.

Preferably, the device further includes a discharge means for transporting the drill cuttings from the drilling platform along an impact-free path by free fall of the discharged drill cuttings against hard objects, causing breakage or crumbling of the drill cuttings, causing pollution will arise from the water surrounding the hearing platform.

Preferably, the discharge means is in a straight path along a portion of its length for dumping the drill cuttings some distance from the drilling platform to prevent collisions of the cuttings with the underwater support structure of the platform. The discharge member can also be loop-shaped in a part of 20. its length.

Preferably, a portion of the discharge member is oriented vertically between the platform and the water and includes an internal looped web, thereby forming an internal helical slide, or a corkscrew-shaped web.

In another aspect, the invention includes a method of treating oil-contaminated drill cuttings from borehole drilling, circulating a drilling fluid for removing the cuttings from the drilled well, which method is characterized by a) separating the grit from the drilling fluid, b) increasing the surface of the grit, and c) mixing the grit to increase the absorption of free oil to the grit by the extra solid oil absorbent material with which the free oil comes into contact with the enlarged surface of the grit.

The invention will be explained in more detail below with reference to the drawing, in which an exemplary embodiment of the device according to the invention is schematically shown; ^ - 5 - give.

Fig. 1 is a perspective and partial cross-sectional view of a offshore platform for an apparatus according to one embodiment.

FIG. 2 schematically shows the drill cuttings treatment device of the device of FIG. 1. ,

Fig. 3 is a partial sectional view of the grit discharge means of the device of FIG. 1.

The drilling tower 10 according to fic.1 has a platform 11, 10 which rests on the bottom 12 of water 13 by legs 14. A tower or mast 15 is mounted on the platform 11 and is used for performing normal drilling operations.

Although a fixed platform at sea has been shown, the invention can equally be applied to other offshore drilling rigs, for example floating drilling vessels or immersion platforms, and to drilling on land.

In rotary drilling, a fluid, usually mud, is circulated in and out of the hole being drilled, for a number of reasons, one of which is to drain the drill cuttings from the borehole. A prior art rotary circulation system for rotary drilling is partially shown in Figure 1 as an example. A guide tube 21 protrudes from the platform 11 down to the seabed 12. Flush is circulated along a drill pipe (not shown) located inside and extends through the guide tube 21.

The mud exits the drill pipe by opening in a drill bit (not shown) at the bottom end of the drill pipe and flows up through the guide tube 21 to the mud return pipe 24. The mud entrains drill cuttings 30 back to the surface and flows from the feed pipe 24 to a treatment unit 27 in which the drill cuttings are removed from the mud on a freeze described with reference to Fig. 2. The rinse is then returned to an unshown storage area for reuse.

When the rinse used does not cover the grit with unwanted pollutants, the grit is sometimes returned directly to the water 13 or to another freely deposited somewhere 8 2 0 4 7 9 3 - 6. However, in certain drilling operations, as is often the case, a special flushing system is used, both at sea and on land, which covers the grit and contaminants. This presents serious problems when depositing the grit. Pii example, when drilling at sea, the debris can be flushed out of the grit when it is returned to the water, causing unwanted pollution. An example of such a flushing coil is the system that conventional oil-based flushing system is stirred. The spent rinse in this system coats the grit ret oil which adheres to it even when it is. grit is mechanically separated from the wash. When this cruise is returned to the water untreated, it is very likely that some of the oil will rinse off and an oil laac may form on the water. Also, in some cases, the grit is "washed" after the separation ret diesel or other suitable oil to remove wash and other chemical contaminants therefrom. However, it is likely that some of the diesel or other oil will adhere to the grit, making it more difficult to dump again *

Referring to Figure 2, the treatment unit 27 includes a plurality of shakers 40 through which the just-contaminated grit initially passes after leaving the rinse return line 24. The shakers 40 have sieves that allow the rinse fluid to pass while the cuttings remain on the screen.

The grit is then transported from the shakers 40 to a storage tank 41 by means of a suitable conveyor 42, for example, a screw conveyor, whereby some mixing of the drill cuttings occurs during transport.

This drill cuttings can contain sand or slate or both. The tank 41 preferably has a stirrer for mixing any sand present with any slate.

The tank 41 further serves to evenly distribute the grit over the rest of the treatment apparatus, also as the grit production rate increases or decreases over time, depending on the drilling.

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From the tank 41, the cruise is further agitated by a web conveyor 43 to a grinder 44. The grinder breaks the drilling noise into smaller particles to provide a larger surface area for further absorption of the contaminating free oil on the grit.

From the grinder 44, the grit is delivered to a blender-rubbing device 45 which allows for further mixing of the grit to cause absorption of the free oil in the grit which was not absorbed during mixing in the grinding process. The mixing-free fin device 45 can also provide additional grinding if more surface is required for the further absorption of the free oil present.

The grit rub 45 is transported to honor. compressor 46, which compresses and extrudes the grit as spheres or briquettes. Many of the known commercially available compressors, which can compress a solid mixture and extrude the mixture as spheres or briquettes, are used, for example those known under the name KG Briquetting System, sold by Komarek-Greaves and Co ., Poseipont »Illinois. The spheres or briquettes then pass over a sieve 47 which serves to separate the spheres, briquettes or other fine material that has insufficient dimensions to sink into water at a rate that is croot enough to prevent it is carried away from the area around the drilling platform by ocean currents, this fine material being recycled through the treatment system.

3q The treated and preferably compressed grit then moves to a discharge means 30 for transporting it to the ocean from the drilling platform. The discharge member 30 is designed such that the grit enters the water without being broken by impact or other contact with the discharge member itself, the drilling platform, with the platform support legs and columns, or with the water itself. In this way, the grit can be dumped into the ocean with minimal contamination of the area around the hearing site with oil from the grit.

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Discharge means 30 may be a vertical hurricane for direct dumping of the cruise to or low next to the drilling platform or, as shown in Fig. 1, may be inclined relative to the vertical along part of its path 5 for the drilling platform take away from the cruise. By depositing the grit enice-distance from the platform, the possibility of breaking the crust upon impact to the platform or its columns is prevented.

As much as the inclined as the vertical portions of the drain member 30 may contain what is commonly referred to as a "trough" for guiding the grit to the water. The gutter, which works as a "wet slide" in a playground, has no corners or sharp bends against which the cruise can bump and break. The grit therefore slides continuously along the chute without free-fall impact against hard objects such as pipe joints and bends from the drain or drilling platform, minimizing breakage or breakdown of the deposited grit, thereby reducing oil contamination in the water surrounding it. platform, may occur.

In detail, the inclined part 31 can be a straight channel or looped one or more times. The vertical part 32 of FIG. 3 may have an inner loop shape 34 wrapped around. a central column. 33, in the form of an internal helical or corkscrew-shaped slide, which prevents free fall of the grit. Preferably, the slide 34 is of sufficient pitch to allow the grit to slide continuously without hindrance. For example, a suitable pitch may range from 45 to 60 °. In a further embodiment, the central column 33 can be formed, whereby the slide 34 then completely fills the inner part 35 of the discharge member.

The discharge member 30 may terminate some distance above the water surface, allowing some free fall of the drill cuttings into the water, or, as shown in Fig. 2, the member may slide the drill cuttings directly into the water. When sliding the grit into the water, the angle of inclination controls the speed of impact of the grit with the water surface, preventing further breaking or disintegration.

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4 # * t - O - when the flow of the oil-contaminated grit has been described by the various parts of the treatment device, the operation is explained in more detail with respect to the flow rate through the system and the addition of 5 possibly absorbent or surfactant material. to promote the absorption of the free oil.

When drilling, the Taalprocess, when there is enough slate in the drill cuttings, provides enough extra solid absorbent surface to absorb the free 1Π oil that contaminates the cuttings. However, when there is too much sand in the drill cuttings, the spheres or briquettes from the compression process become too sandy or too wet and do not hold their shape during the final sieving step or when colliding with the water. In that case, a solid absorbent material such as clay is mixed with the grit so that the grinder 44 and blender-rub 45 provide drill cuttings of suitable composition and moisture to cause the compressor to produce spheres or briquettes that do not break. This absorbent material can be added and mixed with the grit in the storage tank 41 and also in the mixing conveyor 43. A dosing conveyor 49 can be operated to provide a desired rate of absorption of absorbent material from a supply 50 thereof to the feedstock. storage tank 41 and a metering conveyor 51 can be actuated to feed a dust absorbing material at the desired speed from its supply 50 to the mixing conveyor 43.

With regard to the discharge of the grit into the water, it is further noted that the compressed grit must have a composition sufficient to resist breaking and crumbling and must also have sufficient specific gravity to sink to the water bottom. It is therefore important that any fine material exiting the compression device 46 along with the desired spheres and briquettes be separated and recycled through at least a portion of the treatment device and re-treated so that it does not contaminate the water around the drilling platform. For example, the sieve 47 may be selected to discharge only those 82 0 4 79 3 ▼ t - 10 - balls or briquettes with dimensions of 6-12 no.

Fen conveyor 55 returns the separated fine material to the storage tank 41 in advance so that it is recirculated throughout the treatment plant. It is clear, however, that the recirculation can also return the fine material to any desired part of the device, even such that it is recirculated only weirdly by the CCP primer 46.

The flow of the grit, absorbent materials and fine material through the treatment apparatus is described, the speed at which this material moves is described. An important wish is that the treated drill cuttings can be discharged from the device at the same rate or faster than the rate at which the oil-contaminated cuttings are drilled out. Otherwise, storage must be provided for the untreated debris, which may be a problem with an offshore drilling rig. In one embodiment, the power handling device is designed to treat up to 40 tons of drill cuttings per hour.

Fig. 2 can move up to 40 tons of drill cuttings per hour from the shaker 40 to the storage tank 41. The fine material of the sieve 47 also enters this tank, which in this embodiment is about 8 tons per hour. From the stock 50 of absorbent material, up to 8 tons per hour of absorbent material can be dosed to the tank 41 or, if necessary, to the mixing conveyor 43. From the mixing conveyor 43, up to 10 tons per hour of the mixture of drill cuttings, absorbent material and fine material, are recirculated by means of the conveyor 56 back to the storage tank 41 to further serve 30 cm when mixing in this tank, thereby handling 56 tons of mixed drill cuttings per hour and passing through the grinder 44, the mixing rub 45 , the compression device 46 and the sieve 47. Pair the sieve 47 per hour, the aforementioned 8 tons of fine material separates, 48 tons of 35 treated drill cuttings per hour are poured into the water This rate of 48 tons per hour corresponds with the total feed rate into the device of 40 tons per hour of grit and 8 tons per hour of absorbent material added.

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Fluctuations in the drilling speed can be temporarily captured in the storage tank 41. Preferably, the storage tank is filled to about 20 to 30% of the capacity.

If the drilling speed decreases such that in the described embodiment less than 40 tons per hour of grit is produced, the level in the storage tank drops and the treatment device can be switched off until the level rises again. Should the drilling speed, again in the described embodiment, exceed 40 tons per hour of grit, the level in the tank would rise. When the tank begins to reach its maximum capacity and the drilling speed does not decrease, a separate storage facility should be made available or preferably a separate and parallel handling equipment should be provided on the drilling platform, which can then be operated to treat the excess drill cuttings or else drilling should be stopped until the level in the storage tank reaches the level where drilling can be resumed.

•. > 8204793

Claims (10)

1. Apparatus for the treatment of oil-contaminated drilling cuttings from the drilling of a well, wherein a drilling fluid is circulated for removing drilling cuttings from the well, characterized by a) a shaker for separating the drilling cuttings from the drilling fluid, b) a storage tank for collecting the grit, c) a grinding device for increasing the surface of the grit for releasing extra solid oil absorbent material, and d) a mixer for increasing the absorption of free oil in the grit extra solid oil absorbent material obtained by the verifer surface of the ground grit. The device of claim 1, further characterized by a) a supply of solid oil absorbent material, b) means for mixing the drill cuttings with the solid oil absorbent material, and c) means for dosing the flow, var. the solid oil absorbing material 9 to the ribs. 3. Device according to claim 2, characterized in that the mixing members comprise: a) a mixing conveyor for transporting the grit from the storage tank to the grinding device, and b) means for adding extra solid oil absorbing material from the stock to the mixing transducer, whereby the grit is mixed with the solid oil absorbent material while it is being transported from the storage tank to the grinder. 4. Device according to claim 2 or 3, characterized in that the mixing members comprise: a) a stirrer located within the storage tank, b) means for adding the solid oil-absorbing material from the stock to the storage tank, whereby mixing of the solid oil absorbent material with the grit is performed by the stirrer. Device according to any one of the preceding claims, 35 'characterized by means for compressing the milled drill cuttings into individual masses with sufficient density to be able to sink in water. 6. Device according to claim 5, characterized in that a discharge member is arranged for transporting the compressed grit from the hearing platform along a track in which no collisions occur as a result of free fall of the discharged grit without hard objects, as a result of which it breaks or crumbles of the grit will form, which can cause contamination in the water around the drilling platform. 7. Device according to claim 6, characterized in that the discharge member comprises a continuous slide which runs straight over at least part of its length and slopes at an angle to the vertical, through which the discharged grit enters the water at a distance of the drilling platform, by which collision of the discharged grit with the supporting structure under water of the platform is avoided. 8. Device as claimed in claim 6, characterized in that at least a part of the discharge member extends vertically and comprises an internal loop-shaped track *. 2 ° Method for treating oil-contaminated drill cuttings from drilling an out, in which a drilling fluid is circulated for removing the cuttings from the well, characterized by a) separating the cuttings from the drilling fluid, b ) increasing the surface of the grit and c) mixing the grit to increase the absorption of free oil to the grit with the extra solid oil absorbent material, which is exposed to the free oil by the enlarged surface of the grit * A method according to claim 9, characterized in that the oil-contaminated drill cuttings are substantially free of sand so that all free oil is absorbed on the enlarged surface of the cuttings. 8204793