GB2191522A - Treating spent oil-based drilling fluids - Google Patents
Treating spent oil-based drilling fluids Download PDFInfo
- Publication number
- GB2191522A GB2191522A GB08613358A GB8613358A GB2191522A GB 2191522 A GB2191522 A GB 2191522A GB 08613358 A GB08613358 A GB 08613358A GB 8613358 A GB8613358 A GB 8613358A GB 2191522 A GB2191522 A GB 2191522A
- Authority
- GB
- United Kingdom
- Prior art keywords
- oil
- mud
- fluid
- water
- drilling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000005553 drilling Methods 0.000 title claims abstract description 47
- 239000012530 fluid Substances 0.000 title claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 47
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 18
- 239000012071 phase Substances 0.000 claims description 9
- 238000009835 boiling Methods 0.000 claims description 2
- 239000007790 solid phase Substances 0.000 claims 1
- 239000003921 oil Substances 0.000 description 44
- 239000007787 solid Substances 0.000 description 16
- 239000000839 emulsion Substances 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 5
- 239000000654 additive Substances 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000012267 brine Substances 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 239000000356 contaminant Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005755 formation reaction Methods 0.000 description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003995 emulsifying agent Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000002480 mineral oil Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 235000015076 Shorea robusta Nutrition 0.000 description 1
- 244000166071 Shorea robusta Species 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 239000012874 anionic emulsifier Substances 0.000 description 1
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 1
- 229910052601 baryte Inorganic materials 0.000 description 1
- 239000010428 baryte Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 239000007764 o/w emulsion Substances 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000003134 recirculating effect Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000007762 w/o emulsion Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
Oil-based drilling fluids, commonly known as muds, whose oil/water ratio has become too low to be satisfactorily used for continued drilling, subjected to evaporative heating to drive off water, for example so as to bring the oil/water ratio back to specification so that the fluid can be re-used in drilling, or so as to substantially dry the muds enabling their oil phase to be recovered.
Description
SPECIFICATION
Method and Apparatus for Treating Spent Oil-based Drilling Fluids
This invention relates to a method and apparatus for treating spent oil-based drilling fluids, commonly called "muds" in the drilling industry.
Oil-based drilling muds are frequently used during rock drilling, primarily in order to reduce problems with water-sensitive shale formations being drilled through but also in order to realise other advantages such as a more rapid rate of rock penetration and, in oil and gas drilling, less damage to hydrocarbonproducing zones. These muds are essentially water-in-oil emulsions ie the water is dispersed through an oil phase, with oil:water ratios typically varying from 98:2 to 50:50 (volume:volume). The emulsions incorporate additives, selected to achieve specific performance characteristics depending upon the formations being drilled, as is well known in the art.Two typical oil-based mud formulations are given below in both cases being so-called "12 Ibs/gallon muds", indicating their density:
Relaxed Fluid
Component Low Fluid Loss Mud Loss Mud
Oil (gals/bbl)* 27 27
Calcium chloride brine 7 7
(gals/bbl)
Anionic emulsifier 1
(gals/bbl)
Cationic emulsifier 0.2 1
(gals/bbl)
Fluid loss additive 10
(Ibs/bbl)
Organophilic clay 3 5
(Ibs/bbl)
Barite (Ibs/bbl) 220 220
*gal/bbl=U.S. gallons per barrel
The oil component can be mineral oil, diesel oil or crude oil, but low toxicity mineral oils are presently preferred on environmental grounds. The calcium chloride brine normally contains 300,000-350,000 ppm calcium chloride, but saturated sodium chloride brine is sometimes used instead; the high salinity levels are used to obtain an osmotic dehydration effect on shales and claystones.The organophilic clay is a viscosifier for mud system, but other materials having the same effect can be substituted. The fluid loss additive is incorporated when improved fluid loss control is required. The emulsifiers are present to stabilize the water-in-oil emulsion. By rite is present as a weighting agent to bring the mud system to the required density, in this case 12 Ibs/gal. Other components can be added for various purposes eg lime, lost circulation additives, oil wetting agents, high temperature stabilizers, dispersants etc.
As drilling proceeds with an oil-based drilling mud, the drilling fluid becomes contaminated with solid rock particles and often also with water from the formations being drilled. This water, as it is incorporated into the drilling fluid, alters the oil/water ratio of the liquid phase of the drilling fluid, wherebly the fluid gradually loses its properties. In extreme cases, the emulsion can become so diluted with water that it inverts to an oil in water emulsion, with a complete loss of its drilling properties, but even a reduction of more than about 10% in the volume of the oil phase is generally considered to be unacceptable in the oil drilling industry.Since the drilling muds are quite expensive to prepare, it is increasingly economically worthwhile to treat drilling muds whose properties have deteriorated to the point where they can no longer be used satisfactorily down-hole so that they are restored to their original specification and can then be re-used. Reconstitution of spent drilling muds is also attractive on environmental grounds, since otherwise the spent muds have to be dumped.
At the present time, spent oil-based drilling muds are normally reconstituted by first removing the solid contaminants, usually by means of a centrifugal separator, and then the drilling fluid is treated either with a suitable grade of oil, or with a suitable oil/water emulsion, in order to bring the oil/water ratio of the fluid back up to the desired level. Other components are added as required to bring the emulsion to the desired specification. Small volumes of spent drilling mud can be satisfactorily reconstituted at the drilling site by this method if the oil :water ratio has remained reasonably close to the desired value.However, if this ratio has dropped significantly before the mud is treated, the volume of fluid which results after sufficient oil has been added to regain the original oil/water ratio can be so large that it becomes impossible to handle at the drilling site, especially when this is offshore or at a remote in-land location. In such circumstances, it can become necessary to transport the whole or part of the spent mud either to a larger central reconstitution facility, orto a licensed dump, which involves in either case transportation costs, as well as the expenss of preparing or obtaining fresh mud to replace that which cannot be reconstituted on site.
The present invention has been made from a consideration of these drawbacks of the presently used
method for reconstituting spent oil-based drilling mud.
In accordance with the present invention there is provided a method for treating an oil-based drilling fluid whose oil/water ratio is below a desired level to bring the oil/water ratio to said desired level, wherein the drilling fluid is subjected to evaporative heating to drive off the excess water.
The method of the present invention is particularly adapted to the reconstitution of spent drilling muds to restore their oil/water ratio to specification. When used for this purpose, the volume of the treated mud is less than thatofthe mud prior to treatment, by the volume of water which is evaporated off, in contrast to the increase in volumes which result from the addition of make-up oil in the presently used reconstitution process. The method of the present invention therefore is more often able to be conducted at the drilling site, for which purpose portable mud evaporation units can be provided to be moved from site-to-site.
Instead of treating the entire volume of drilling mud at one time, it is alternatively possible to treat only a part of the mud in order to retain the oil/water ratio of the entire volume of drilling mud at the required level.
Thus, a portion only of the mud can be withdrawn and then subjected to evaporation so as to bring its oil/water ratio to a level above the desired level for drilling, whereafterthe concentrated mud can be returned to the remaining, untreated, mud to achieve an overall oil/water ratio at the desired level. This expedient is particularly useful when the treatment is to be conducted on site.
When the method of this invention is used to reconstitute spent drilling muds, it is normally desirable that solid contaminants should first be removed from the mud to be treated. This can be conveniently accomplished using a conventional centrifugal separator Also, following the evaporative treatment the other components of the mud can be made up to specification as required.
The method of the present invention can also with advantage be used in the treatment of muds which are to be disposed of, rather than reconstituted for re-use. In this case, the evaporation preferably is conducted so as to recover the oil phase. This can be accomplished by recirculating the mud through the treatment process a sufficient number of times to ensure substantially complete removal of both the water phase and also the solid components of the mud which can then be transported to a licensed dump.
A preferred apparatus for conducting the evaporative treatment of the present invention comprises a storage vessel for receiving oil-based drilling mud to be treated, a mud-preheater connected to the storage vessel to receive mud therefrom, a mud evaporator connected to receive pre-heated mud from the mud pre-heater to heat the mud to a temperature above the boiling point of water to evaporate off water from the mud, and means for conducting the hot treated mud from the evaporator in indirect heat-exchange contact with the starting mud passing through the mud preheater to preheat the mud passing to the evaporator.
Such apparatus, which can be designed to operate on either a continuous or batch basis, can advantageously also provide for recirculation of the mud through the evaporator one or more times in the event that the required water-removal is not achieved in a single pass. A separator, such as a centrifugal separator of conventional design, is preferably also provided to remove solid contaminants from the mud before it is passed to the mud preheater.
Referring now to the accompanying drawings, Figure 1 is a flow diagram illustrating a preferred embodiment of the method of this invention applied to the reconstitution of an oil-based drilling mud. As illustrated in the flow diagram, the mud leaving the centrifuge is tested to determine its solids content, and if this is above about 10% by weight the mud preferably is recirculated through the centrifuge before passing to the preheating and evaporation stages. Similarly, the mud leaving the evaporator is tested to determine its oil/water ratio, and if this is found still to be too low the mud is recycled through the evaporation stage of the process.
Figure 2 of the drawings shows schematically a preferred apparatus of the invention for carrying out the method illustrated in the flow diagram of Figure 1. As illustrated, the apparatus includes a spend mud receiving tank 10 which continuously or periodically receives spent mud for treatment through an inlet line 12. Mud is withdrawn from receiving tank 10 through line 14 by a pump 16 and pass through a centrifugal separator 18 of conventional design in which small pieces of rock of other solids contamination are removed. The mud leaving the separator is sampled to determine its solids content, and if necessary the mud is reciculated via line 44 through the separator to reduce its solids content sufficiently. It is preferred that the solids content of the mud should not be much above 10% by weight before it is passed from the solids separation stage.
When an acceptable solids level has been reached, the mud is then passed through line 20 to a preheater 22 where it is preheated by indirect heat exchange contact with hot mud leaving the evaporator, as will be described in greater detail below. The preheater 22 conveniently takes the form of a coiled tube located in a suitable vessel and through which the cold mud is passed while hot mud from the evaporator flows, counter-current to the mud flow, over the coiled tube through the containment vessel. In the preheater, the cold mud will typically have its temperature raised by about 20"--40"C.
The preheated mud then passes through line 24 to the evaporator, generally designated 26, and which in the illustrated embodiment consists of a mud heating section 28, where the mud is heated, generally to a temperature in the range 90"--100"C, and whose mud outlet is connected by line 30 to a tank 32 where the water vapour flashes off from the hot mud as it is received in the tank. The heating section 28 preferably is in the form of a heated coiled tube through which the mud is passed. Any suitable heating means may be employed to heat the mud passing through the coiled tube, but an electrically heated oil bath provides for ready control of the mud temperature. The hot mud typically will have a temperature of from about 70"--100"C as it leaves the heating section 28.The tank 32 which receives the hot mud should have a volume sufficiently large to allow the water vapour to flash off before the mud leaves the tank. Preferably, and as shown, a vacuum pump 34 is included in the vapour outlet from the tank 32 to draw the water vapour off and thus help to prevent water re-condensing on top of the mud in the tank. The mud collecting in the tank 32 will thus have an oil/water ratio which is higher than that of the mud entering the heating section 28.
From tank 32, the still hot mud is pumped by pump 36 to the preheater 22 where it flows counter-current to the cold mud passing through the coiled tube of the preheater and gives up to the cold mud some of its useful heat. The treated mud leaves the preheater through line 38 where its oil/water ratio is sampled. If this ratio is acceptable ie it has risen to the desired level, the mud can be passed through line 40 to product storage tank 42, for eventual re-use in drilling. Alternatively, the treated mud can be returned to the mud receiving tank 10, even though its oil/water ratio is acceptable, in order to raise a certain extent the oil/water ratio of the mud present in that tank.
If, on the other hand, the mud in line 38 is sampled to have an unacceptably low oil/water ratio, thus preventing its immediate re-use in drilling, the mud should be recycled through the evaporator 26. Three alternative paths for the mud to be recycled are provided in the illustrated apparatus. Thus, the mud can be passed through line 40 back into the receiving tank 10, where it will mix with any mud in that tank which is awaiting treatment, and from whence it will be passed through the apparatus as described above, except that optionally it can by-pass the centrifugal separator 18 via line 44. Another possibility is to pass the mud directly via line 38 via line 46 into line 20 and thence into the preheater 22.In a modification of this last recirculation route, the mud can be passed, via line 44, first through the separator 18, to reduce its solids content, before being passed into the preheater 22.
The reconstituted mud which collects in the product storage tank can be periodically withdrawn through line 48 for re-use in drilling. Alternatively, the apparatus can be operated so as to substantially drive off all the water from the mud, and to separate the oil phase from the solids phase. The oil phase can then be recovered for further use, whilst the separated solids can be passed to waste. A more complete final separation of the oil and solids phases can be obtained, if desired, by the provision of a press filter, or similar, in line 48.
It will be apparent that numerous modifications can be made to the apparatus shown in Fig. 2. For example, the preheater 22 could be omitted, which although leading to some loss in energy efficiency might be desirable in a small-scale, portable plant to be used at the actual drilling site. Again, by operating under reduced pressure, it would be possible to drive off the water in the heating section 28 at a lower temperature than when operating under ambient pressure conditions. In order to stabilize the reconstituted mud, a shearing device could be provided in line 40 to reduce the size of the suspended water drops in the emulsion. A suitable mud shearing device is a high pressure pump.
Claims (5)
1.A A method for treating an oil-based drilling fluid whose oil/water ratio is below a desired level to bring the oil/water ratio to said desired level, wherein the drilling fluid is subjected to evaporative heating to drive off the excess water.
2. A method according to Claim 1, wherein sufficient water is evaporated to restore the oil/water ratio to a level suitable for the product fluid to be re-used in drilling.
3. A method according to Claim 1, wherein the drilling fluid is substantially dried, and the oil phase thereof is recovered substantially free from any solid phase components thereof.
4. A method according to any preceding claim, wherein the drilling fluid is heated to evaporative temperatures in two stages, the first stage being a preheat using the hot fluid from the second stage as the heat source.
5. Apparatus for treating an oil-based drilling fluid whose oil/water ratio is below a desired level to bring the oil/water ratio to said desired level, the apparatus comprising a storage vessel, for receiving an oil-based drilling fluid to be treated, a preheater connected to the storage vessel to receive said fluid therefrom, an evaporator connected to receive preheated fluid from the pre-heater to heat the fluid to a temperature above the boiling point of water to evaporate off water from the fluid, and means for conducting the hot treated fluid from the evaporator in indirect heat-exchange contact with the fluid passing through said preheaterto preheat the fluid passing to the evaporator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08613358A GB2191522A (en) | 1986-06-03 | 1986-06-03 | Treating spent oil-based drilling fluids |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08613358A GB2191522A (en) | 1986-06-03 | 1986-06-03 | Treating spent oil-based drilling fluids |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8613358D0 GB8613358D0 (en) | 1986-07-09 |
| GB2191522A true GB2191522A (en) | 1987-12-16 |
Family
ID=10598798
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08613358A Withdrawn GB2191522A (en) | 1986-06-03 | 1986-06-03 | Treating spent oil-based drilling fluids |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2191522A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2215364A (en) * | 1988-03-08 | 1989-09-20 | Advanced Refinery Tech | Process for treatment of drilling mud |
| US5093008A (en) * | 1989-02-28 | 1992-03-03 | Geo Drilling Fluids | Process and apparatus for recovering reuseable water form waste drilling fluid |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB762182A (en) * | 1953-07-15 | 1956-11-28 | George Henry Davis | A continuous-flow evaporator for concentrating brine |
| GB1268715A (en) * | 1968-07-16 | 1972-03-29 | Exxon Production Research Co | Drilling with controlled water content water in oil emulsion fluids |
-
1986
- 1986-06-03 GB GB08613358A patent/GB2191522A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB762182A (en) * | 1953-07-15 | 1956-11-28 | George Henry Davis | A continuous-flow evaporator for concentrating brine |
| GB1268715A (en) * | 1968-07-16 | 1972-03-29 | Exxon Production Research Co | Drilling with controlled water content water in oil emulsion fluids |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2215364A (en) * | 1988-03-08 | 1989-09-20 | Advanced Refinery Tech | Process for treatment of drilling mud |
| GB2215364B (en) * | 1988-03-08 | 1992-04-01 | Advanced Refinery Tech | Process for treatment of drilling mud |
| US5093008A (en) * | 1989-02-28 | 1992-03-03 | Geo Drilling Fluids | Process and apparatus for recovering reuseable water form waste drilling fluid |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8613358D0 (en) | 1986-07-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |