NO830526L - PROCEDURE AND DEVICE FOR BREAKING COOKIES - Google Patents

Description

The invention relates to technology used in oil fields, in particular devices for drilling and production from oil wells. Self.

if it is not limited to any particular use, the invention is particularly suitable for drilling along the continental shelf where problems with the surroundings are particularly difficult when oil-based drilling mud is used.

The invention produces a device and a method for removing hydrocarbons that are bound to rock fragments that appear when drilling wells, especially where an oil-based drilling fluid is used.

It is consequently a goal of the present invention to remove the film or layer of oil components in the oil-based drilling fluid from cuttings that emerge during drilling operations in oil and gas wells.

It is another aim to produce a method and device for efficient utilization of gaseous products formed by evaporation of hydrocarbons, which adhere to drilling cuttings.

It is a further aim to produce a device for burning wood chips, with a heating zone for the removal of hydrocarbons, the wood characterized by a high degree of resistance to corrosion, erosion and chemical effects from the products evaporated from it.

It is another object of the present invention

to form one. continuous two-stage device and a process for burning hydrocarbons and other vaporized materials from drilling cuttings, each stage being performed in a device with a common shaft for transferring materials into the first stage, from the first to the second and from the second stage out from the device in an oil-free state.

A further aim is to produce a device which produces part of the heat required for the operation of the burner, from gas products produced by the heating of the drill cuttings.

A further aim is to recover heat during introduction

of oxygen into the stream with the evolved vaporized hydrocarbons.

It is a further object to provide a method for carrying out the foregoing objects.

A further one is to produce a treated pulverized solid product containing less than 1/1,000,000 hydrocarbons.

In the drawing, Figure 1 shows a section of a preferred embodiment of the invention where two processing stages are arranged with the stages interconnected by a common shaft for operating each stage and for transferring materials to and from each stage, Figure 2 shows a side view of a second embodiment of the invention, partly in section, where the first stage has a conical surface where contaminated drilling cuttings are fed into the interior and from which heated cuttings are removed by peeling, scraping etc., the first and second stages in it . another embodiment of the invention is connected with a common shaft for transferring materials through the second stage and between the stages, Figure 3 shows a cross section along 3-3 in Figure 1, Figure 4 shows a cross section along 4-4 in Figure 1, Figure 5 shows a cross section along 5-5

on figure 1 and figure 6 shows an enlarged partial section, corresponding to a part of figure 3 which shows the laminar flow with liquid inner and outer layers.

When an oil well is drilled from an offshore or inland barge or rig through various geological formations, chemicals are added to the drilling fluid to provide thermal stability, lubrication and to consolidate the geological components in the hole wall to prevent the danger of collapse of the walls around the drill pipe and to further avoid the need to enlarge the hole or wedge the drill pipe. Drilling fluid is continuously pumped down the borehole and cuttings or material that is cut out of the formation floats in the fluid and is raised to the surface for separation and recycling of the drilling fluid back to the borehole. While water-based drilling fluids are suitable for drilling in special geological formations, in other special formations it is necessary or desirable to use an oil-based drilling fluid. If water-based drilling fluid is used, the separation is a relatively simple problem. However, separation of cuttings from an oil-based drilling fluid includes permanent disposal by dumping in the sea offshore or placing in a pond on land due to the hydrocarbon contamination of the cuttings from the oil components of the drilling fluid. To the extent that strict regulations now cover the discharge of biological contaminants both on land and offshore, it is necessary to remove the oil that penetrates the cuttings when oil-based drilling fluids are used and also

to remove the small residues in water-based cake. In those cases where a drilling operation must necessarily use an oil-based drilling fluid and where it is not economically appropriate or technically possible to complete a well with water-based fluids, it becomes of significant importance in an economical way to remove oil-contaminated cuttings without endangering the environment.

The two existing methods for treating drilling cuttings that are contaminated with oil, which include washing the oil out of the cuttings and burning the oil, are not very effective. In addition, leaching creates additional problems in exhausting the oily chemical residues and incineration presents the problem of incomplete combustion and a resulting dense smoke causing air pollution problems that can be as serious as the water pollution problem sought to be avoided. Regulations in the United States, European countries and elsewhere either prohibit or significantly restrict the dumping or other discharge of pollutants. Various bodies and institutions have issued regulations and standards where special criteria define a breach of the oil pollution regulations if residues are visible on the water after the waste has been drained. This also includes boiling oils and draining wash water and any draining of any type of oil from any source is generally prohibited by applicable regulations. On land, further considerations are required in connection with leakage to the groundwater systems and the environment's impact on ecological systems in towns and villages, and the special requirements must be met. Substantial fines and potential punitive damages effectively preclude the use of oil-based drilling fluids except where absolute necessity requires an expensive solution to the waste problems and there is often a decision to close the well in cases where the far better use of oil-based fluids results in significant cost and potential savings which is not sufficient to overcome these cost factors. With the help of the present invention, a method is produced for the discharge of oil well cuttings that are contaminated with oil from an oil-based drilling fluid or mud and that gives a clean, environmentally safe and economically favorable result.

Figure 1 shows a simple continuous device where each half is shown with some overlap for the sake of overview. The burning device 10 for cake comprises a first stage

12, another step 14 and a leg 16 for gas collection and recycling. Drilling fluid and cuttings are pumped together into a storage container until it is ready for processing. The contaminated drill cuttings are mechanically separated from the recyclable drilling fluid by a gravity screen or vibrator and then introduced into a vibrating hopper to allow variation in the feed rate. Accordingly, first stage 12 comprises intake pipe 20 to receive contaminated drilling cuttings in the form of a slurry from the funnel, the slurry entering the space 22 where a screw 24 forces the slurry in the space 22 downwards into and through the first stage 12. The screw 24 has blades mounted on the shaft 26 which is driven by drive means (not shown) for clockwise rotation, seen from above. The axis 26 corresponds to the axis of the device 10 and allows all material transport to be controlled from a single drive source. The drum 30 in the first stage rotates with the shaft 32, concentric with the shaft 26 and driven by the same drive device, and the drum 30 has two vanes 34 to press the material which is processed into the first stage 12 downwards through the tube 36. The drum

30 is rotatable and the pipe 36 can also be rotated to vary the relative speed of rotation between the drum 30 and the pipe 36. Furthermore, the pipe 36 is mounted on bearing 38 and can be driven by the worm gear 40 at a desired speed of rotation either clockwise or counter-clockwise. The .36 pipe is preferably made of a corrosion-resistant high-temperature alloy such as, for example, a chrome-nickel alloy, sold under the trademark "Inconel". Heating coils 42 or other heating devices surround or are connected to the heated portion of the pipe 36 to raise the temperature of the pipe and the cake which is pressed through the gap 44 between the drum 30 and the pipe 36 to a temperature of approximately 760°C. The development of the majority of the hydrocarbon materials occurs in the first stage 12 as such gases pass upwards into the receiving chamber 46 and then downwards through the annular 48 in the direction of the arrows. The shaft 32 is centered in the housing 50 by means of air-cooled bearings 52. Insulation materials 54 help to retain the heat that would otherwise be lost by radiation, water conduction or convection. As a result of the heating in the first stage 12, the incoming drill cuttings are somewhat dried and a cake is formed in the gap 44 as vaporized gases begin to evolve. The cake, which is still a sludge, is continuously removed under the action of the blades 34, falls into the discharge area 60 into the gas recycling pipe 62. The cake falls into the second stage 14 from the narrowed pipe section 66 and passes through the heated gap 68 in the second step 14. The gap 68 is formed between the second stage drum 70 and the second stage tube 72 which is preferably also made of a nickel-chromium alloy which can withstand high temperatures, typically around 1425°C due to the corrosion problems associated with fixed - the abrasive properties of the particles that pass through the gap 68 as well as the corrosion as a result of the gas problems that appear during heating of the solid particles. The six blades 74 attached to the drum 70 produce sufficient pressure that, together with the temperatures that occur between the pipe 72 and the drum 70, the residues on and in the cuttings material passing through the gap are completely vaporized and ignited. The product that penetrates from the outlet 76 with all digestible residues is removed by falling down through the hollow tube 78 towards the block 80 which is intended to produce the necessary resistance to produce the internal pressures necessary to complete the combustion of the mass that can be evaporated. The auger blade 79 discharges the residues through the matrix block 80. In addition, the block 80 allows all unburned gases contained in the cakes to be vented through a collection manifold 82 and recycled through the leg 16 for gas collection and recycling. The now acceptable effluent leaves the device through the outlet pipe 84 where a jet of water created by the water inlet 86 may serve to cool and consolidate the material for pelletizing or otherwise bringing it into a suitable form for handling, or to form a sludge which can be discharged on the seabed. The resulting material can be emptied without regard to the potential danger of breaching ecological or environmental regulations. Preferably, the tube 72 is heated electrically by means of resistance heating between

the electrodes 88 and 90 although other devices for heating can also be used, such as for example induction heating, arrangement of coils corresponding to the coils 4 2 and the like. The drum 70 is heated internally by the combustion of vaporized gases that penetrate through the recycling pipe 94 in the leg 16. Compressed air or oxygen penetrates through the line 96 and complete combustion occurs in the drum 70, as the exhaust gases penetrate through the perforations 98 on the shaft 100. sharing a desired pressure in the drum 70 is possible by using the gas lock device 102. Additional air or oxygen can be introduced through the line 104 and provide heating for the lower arm 106 which is used for heating the matrix block 80, as the combustion gases escape through the outlet 108 to a extinguishing flame etc. The arrangement of the lower part of the device is best seen in Figure 5 where the vortex effect that can be achieved is clearly shown. The channels 110 in the matrix block 80 guide the product through the opening 112 where pulverization occurs and where selection of the size and number of openings determines the pressure achieved in the second stage 14. The drum 70 is held on the shaft 114 and rotates when the shaft 114 rotates clockwise. The igniter 116 ensures complete combustion of the gases in the lower part of the leg 16 for gas collection and recycling. To minimize heat loss, insulation can be placed in the area 120 between the tube 72 and the housing 122. Preferably, the tube 72 and the drum 70 are made of a nickel-chromium alloy, sold under the name "Inconel".

Due to the closed loop venting of the combustion gases in the system, the device creates 10 small hazards at drilling sites and its straight line design and single drive shaft allow it to be placed between decks or outboard on the platform of an offshore drilling rig to minimize the space requirement for the installation. By arranging a separate electrical generator, the electrical requirements can be easily satisfied without requiring power from generators that have other purposes. Furthermore, the unit itself is designed in one piece and is therefore easy to move. After the operating temperature has been reached, the combustion products will essentially maintain the operating temperatures in most cases where the requirements for electrical power for heating are dramatically reduced and through-heating can produce operating efficiencies as high as 90%. The preferred temperature of 14-25°C in the second step 16 can be easily achieved.

In the second form of the invention, shown in figure 2, cuttings, which are separated from a recyclable oil-based drilling fluid at an edge, are introduced automatically from a vibratory funnel into the intake pipe 130 in the device in figure 2, generally shown at 132. Raw drilling cuttings from the pipe 130 need into the first stage 134 and is then transferred to the second stage 136 with recirculation of evolved gases in a closed recycling loop 138. Drive devices 140 rotate the shaft 142 which drives the first stage 134 on the shaft 144 and drives the screw conveyor 146 on the shaft 148 at the same time as it drives the dust blower 150 via the shaft 152. The drive device 14 0 is an electric motor that works at low speed and with high torque and has an optional low-speed drive shaft 142 or a high-speed drive shaft 142 and corresponding gear transmission in the gear 153.

Raw drilling cuttings from the intake pipe 130 pass into the first stage 134 by means of the sling ring 158 which distributes the raw contaminated cuttings uniformly over the inner surface 160 of the conical part 164. When using heating coils 162 of the induction type, the conical part 164 provides preheating of the drill cuttings to approximately 76 0°C. As a result of the heating at this stage, the cake dries somewhat and forms a cake in the interior of the conical part 16 4 flat 16 0 and begins to emit vaporized gases which are collected in the tube 170 by means of the fan 172. The cake which is formed in the interior of the conical part is continuously removed by scraping devices and falls into the pulverizing device 174 which reduces the sawdust to a granular material with a size of about 200 µm. Heating in the interior of the conical part 164 is facilitated by the heating element 176 which works with the return line 178 from the device's last stage. The sawdust in granulated form is pressed by the screw conveyor 146 into and through the second stage 136 under high pressure produced by the screw conveyor 146. The screw conveyor 146 is arranged in a stainless steel pipe unit 180 which is connected to the pulverizing device 174 by means of the flange 182. The screw device 146 forces the cuttings into the corrosion-resistant second stage tube 182 which is preferably made of high-temperature corrosion-resistant chromium-nickel alloy, for example that sold under the name "Inconel". Slag in the second stage 136 fills a relatively narrow clearance 154 between the shaft 152 and the tube 182 where they are heated to a temperature of preferably 1,425°C.

The extreme pressure and temperature of the second stage 136 causes the residual constituents on and in the cake to completely vaporize and ignite. The second stage 136 is further enhanced by the introduction of vaporized gases from the first stage which, when mixed with air injected from line 186, heats the hollow shaft 152. These gases serve not only to reduce the energy requirements required to maintain the heating temperature but also as a supplement for igniting the gases that vaporize in the second stage 136 and pass into the lines 178. The cuttings that seep out from the pipe 182 are now in powder form and have removed all oxidizable residual components, after which they are extruded through the matrix block 188 Preferably, the size of the opening through which the product passes is about 0.793 mm, although this dimension can be varied. The resistance required to develop the internal pressure necessary to complete the complete combustion of vaporized products is a result of the resistance provided by the matrix block 188 and any unburned gases present in the cake can be vented through a collection manifold in the matrix block 188 and is recycled through the line 178 back to the pulverizer 174 for preheating the incoming solids.

The purified solids emerging from the matrix block 188 are cooled and consolidated by means of water from the water jet 190 and can be pelletized or otherwise brought to an appropriate form for handling. The dust loop 150 can optionally be used for emptying the cleaned material into water.

Due to the closed venting loop for flammable gases

in the system, the device poses little risk to drilling sites and its rectilinear construction allows it to be placed between the decks or on the outside of a platform on an offshore drilling rig so that the space requirements for the installation are minimized. All important criteria that are considered necessary for the successful development of an exhaust device for

drilling cuttings are built into the described invention. It should be noted in particular that the facility is effective with drilling cuttings originating from commonly available rock types including clay-shale characterized by several fractional planes in which oil can be embedded. Consequently, there can be an extremely thorough removal of hydrocarbon materials, including those that naturally occur in the rock.

Furthermore, a layer effect occurs when passing through the clearance 154 in the device in figure 2 or in the clearance 68 in the device in figure 1. A certain degree of fusion or liquid formation occurs in drill cuttings that are heated to the temperature in the clearance, with the result that erosion of nickel-chromium - the alloy that forms the clearance is minimized and it has been found that long periods of use are achieved without the need for replacement when a nickel-chromium alloy such as "Inconel" is used.

During a test of the device, essentially as described in connection with Figure 2, two samples of cake were analyzed. Sample 1 represents cake before treatment, while samples 2

and 3 represents cake treated in the facility. Tests were carried out to measure the oil content, the soluble metal content and the reaction of the shale cake samples to methylene blue.

Table 2 shows the results of the tests. The tests for oil and fat were carried out by extracting 25 g from each sample, with Freon. This extract was then analyzed by infrared spectroscopy against a standard control set.

The water-soluble constituents in samples 2 and 3 were measured by extracting 25 g from each sample with 25 ml of ionized water, after which the extract was filtered and analyzed by atomic absorption spectroscopy. The cation exchange capacity of samples 2 and 3 was determined with a methylene blue test. The measured cation exchange capacity of less than 0.1 meq/100 g cake indicates that the cake has been transferred to an inert ceramic material by the cake cleaning device. This test was carried out in a sludge with 50 g cake per 100 mm ionized water. The sludge was then filtered with methylene blue solution at the end point and the cation exchange capacity was calculated. The loss on ignition for samples 2 and 3 indicates that oxygen reacted with some of the components in these samples. The moisture content test was performed by drying pre-weighed samples in porcelain crucibles at 105°C over two hours. Moisture content was calculated and the samples were then placed in a muffle furnace in an oxidizing atmosphere and heated to 950°C and held at this temperature for two hours. After cooling, the samples were weighed again and the loss on ignition was calculated. The results of these tests are listed in table 2.

As can be seen, hydrocarbons have been reduced to below 0.2 parts per million. After mixing with seawater, the shavings leave no visible film on the surface of the water.

It should further be noted that waste solids of various types that arise from an oil drilling rig can be mixed with cuttings for discharge with the device according to the invention. For example, sewage water, pulverized waste etc. on a mobile offshore drilling rig is handled so that the nature conservation problems can be handled in connection with the treatment of solid waste substances that arise during the operation of an offshore facility.

Furthermore, smaller amounts of hydrocarbon pollution can be handled with the present device, as occurs on beaches etc. where oil spills have accumulated on sand or other beach materials. Consequently, the transportability of the present device makes it suitable for beach use, either with transport on land or on a barge or other sea vessel parallel to the beach to treat contaminated beach material.

An advantage of the present construction in each form of the invention is that there are no closely moving parts in the second high temperature stage and consequently the laminar flow with the slow moving solids can serve to reduce the resistance between the material and the high temperature components of "Inconel". As is known, erosion is a continuous problem in high temperature devices and conventional solutions to the problem of erosion include hard surfaces or the use of expensive tungsten carbide alloyed materials. However, the chrome-nickel alloy according to the present invention has been found to be superior to such materials in practice without the need for replacement, as is traditionally the case. In a test where cooling of a sample was carried out, it appeared that the solid in the clarifier had developed a liquid film 73 on the surfaces of the drum 70 and the tube 72 as shown in figure 6, which also shows the laminar flow of the cake. Such a film will contribute to the high resistance to erosion that exists under operating conditions of the present device. Preferably the clearances are approximately 4.7625mm, but can be up to 15.875mm with good results. However, if the clearance is greater than this, this will result in less good treatment.

It is an important feature of the present invention, when it is constructed as shown in a unit, that it results in an explosion-proof device. In addition, a pressure vessel can be built around the entire device to provide additional insurance against explosions. With the rotating conical part in the device in Figure 2 in the preheater, the sawdust is distributed over a large area so that the development of hydrocarbons and moisture in the first stage 134 is simplified.

Claims (10)

1. Device for removing combustible material from cuttings from well drilling operations, where the cuttings consist of a mud with flakes from underground layers, an oil-based phase with hydrocarbons and an aqueous phase, characterized in that it comprises a preheating step where the cuttings are preheated and the essential part of the hydrocarbons and the aqueous phase are removed, a second stage axially flush with the preheating stage and receiving material therefrom, the second stage comprising a vertically arranged open cylindrical outer tube with intake devices at the upper end and outlet devices, an inner support shaft arranged concentrically relative to the outer tube, a screw conveyor on the shaft for transporting the sludge through the annular space between the outer tube and the supporting shaft, the outer tube being arranged to heat the sludge in the annular space so that the hydrocarbons are vaporized and removed from the tube and a residual solids that are substantially free of hydrocarbons can be removed from the tube outlet device, a collection tube attached to the preheating stage, a ventilator arranged between the collection tube and the preheating stage for collecting the vaporized hydrocarbons, where the vaporized hydrocarbons are led away from the preheating stage, and gas injection devices for introducing a gas containing oxygen to the vaporized hydrocarbons in the collection tube , the injection device being connected to the cylindrical tube for igniting and burning the vaporized hydrocarbons and introducing them into the cylindrical tube. 2. Device according to claim 1, characterized in that a pulverizing device is connected between the preheating stage and the outer tube, the pulverizing device being connected to the outer tube by means of a screw conveyor. 3. Device according to claim 2, characterized in that the preheating step comprises a hollow conical part with an inner surface against which the wood chips are flung, the conical part having heating devices to raise the temperature of the wood chips at the inner surface, with the development of the vaporized hydrocarbons and moisture , the conical part having scraping devices for removing material therefrom, so that solids pass down into the pulverizing device. 4. Device according to claim 3, characterized in that the conical part is heated by induction heating to a temperature of around 649°C. 5. Device for removing combustible material from cuttings obtained from well drilling operations, where the cuttings consist of a mud with flakes from subsoil layers, an oil-based phase with hydrocarbons and an aqueous phase, where an open cylindrical outer tube has intake devices and outlet devices, an internal impact tea drum arranged concentrically in relation to the outer tube and drive devices for introducing the sludge through the intake devices into the annular space between the outer tube and the support drum, the outer tube being arranged for heating the sludge in the annular space so that hydrocarbons evaporate and is removed from the pipe and that a remaining solid substance is essentially free of hydrocarbons and can be moved from the outlet device in the pipe, that it has a preheating step where the cake is preheated and the essential part of hydrocarbons and the water-containing phase is removed, the preheating step being connected to the cylindrical outer tubes using the preheating stage and the outer tube is inner sealed for continuous operation, characterized in that the device has a common axis through the preheating stage and the cylindrical outer tube, that the drive device is arranged on a shaft in common with the axis, that the shaft can be driven using the drive devices connected to the device, that the vaporized hydrocarbons can be collected in a collection tube between the preheating stage and the drum in the outer tube and that gas injection devices are arranged for introducing a gas containing oxygen to the vaporized hydrocarbons in the collection tube, that the preheating stage comprises a cylindrical drum with screw blades which can be received in a rotatable cylindrical tube so that the relative rotation of the drum and the rotatable tube can be adjusted, the drum being centered on the shaft by means of bearings. 6. Device according to claim 5, characterized in that the outer cylindrical tube receives a cylindrical drum with several screw blades, where the cylindrical drum is mounted on the shaft and the cylindrical tube has a pair of separated electrodes for heating by means of electrical resistance. 7. Device according to claim 6, characterized in that a matrix block receives the residual solids which are emptied through the outlet device, the matrix block having several openings for pulverizing the residual solids and to enable the build-up of pressure in the cylindrical tube. 8. Method for removing combustible and evaporable materials from a sludge containing such materials which are present when removing the sludge as a thin film between a first pair of surfaces, at least one of which is heated to remove a substantial part of the combustible and evaporable material from the sludge as a gaseous product, then moving the sludge as a thin film between another pair of surfaces, at least one of which is heated to remove the remainder of the combustible and volatile materials from the sludge and to discharge the residuals substantially free of combustibles and volatile materials, moving the surfaces in each pair of surfaces relative to each other while moving the thin film of mud therebetween, each step of moving the thin film comprising transporting the thin film between a pair of concentrically spaced cylindrical surfaces with an annular clearance in between with at least one of the surfaces rotating and with a screw conveyor blade in clearances n to move the thin film and move the solids of the sludge, the rotation of at least one cylindrical surface comprising rotating both of the cylindrical surfaces forming the first pair of movable surfaces with their relative speed of rotation adjustable. 9. Method according to claim 8, characterized by heating the first pair of surfaces to around 760°C and the second pair of surfaces to around 1425°C. 10. Method according to claim 8, characterized by burning the gaseous product which is produced by movement of the film through both pairs of surfaces, the heat produced being used to heat the surfaces to thus reduce the need for energy supply from the outside.