A message on the topic of cleaning up drilling waste. Ways and methods of disposal of drill cuttings
During the drilling process, it becomes necessary to clean the well and the surrounding surface from environmentally harmful substances. The ACONIT company offers a full range of services for drilling waste disposal. We will quickly remove and safely recycle sludge, waste water and waste solution, which over time can turn into a hard, stubborn layer.
The process of drilling waste disposal is subject to special requirements from the protection authorities environment. Industrial and technological residues contain a large range of mineral and organic pollutants that are dangerous to natural environment. High-quality disposal of drilling waste is carried out by burning, freezing, burial, physical and chemical processing, and biological decomposition.
High standards of the ACONIT company in the disposal of drilling waste
Our activities comply with all environmental and technical standards. Pumping, removal, removal and disposal of drilling waste are carried out. Professional specialists use reliable modern special equipment and work quickly.
Dispose of bentonite (drilling mud) – difficult task. It absorbs water and can expand 10 times in volume. To remove moisture from a gel-like product, you need big square, a lot of sand or soil and special chemical conditions. Not every company can handle a lengthy and labor-intensive process, but ACONIT employees are ready to handle drilling waste disposal of any complexity.
our clients
- Enterprises specializing in horizontal and vertical directional drilling, including using the “wall in soil” technology;
- excavation firms that build roads and tunnels;
- construction organizations performing earthworks.
You can order professional drilling waste disposal from us and get all necessary information. We guarantee high quality works that ensure environmental protection.
- How much great danger Are drill cuttings and drilling fluids important for the environment?
Drill cuttings and drilling fluids belong to the Sh-1U hazard class. And this is understandable, because a variety of chemical reagents are added to the drilling fluid that powers the drilling process. Some, for example, should reduce the fluid yield of the formation, others should reduce the viscosity of the solution, and others should promote thermal stabilization. Add here inhibitors, defoamers, hydrogen sulfide absorbers, pH stabilizers - you can’t list everything, but all together this creates a rather dangerous environment for the environment.
- Andrey Anatolyevich, how do they solve the problem of neutralizing and processing drilling waste in Russia?
Several technologies have been developed in our country.
Re-injection technology drill cuttings successfully used in many parts globe, where oil production is carried out, including in Russia at Priobskoye field Gazpromneft-Khantos and in the Sakhalin-1 and Sakhalin-2 projects.
The technology represents the process of grinding drill cuttings (solid phase), mixing it with liquid drilling waste (OBR, OBZh) to form a pulp and pumping the resulting pulp into underground horizons for disposal.
The advantages of this technology are ensuring zero discharge, complete recycling of both solid and liquid waste, no risk of waste leakage during transportation, full control of the process by the operator, economic efficiency.
On Far East American company SVAKO also uses the method of injection into the reservoir, the same company also works in Western Siberia. Today, it is this method that allows us to dispose of all drilling waste with 100% efficiency.
The second method, which has shown good results in Russia, is the separation of drilling fluid from drill cuttings, which allows the use of process water in technological process to maintain reservoir pressure. In this case, the drill cuttings are brought to the U hazard class state and are used for backfilling quarries and in construction. Unfortunately, most often the disposal problem in Russia is solved simply: free liquid is pumped out of the pit where drill cuttings are located and dumped onto the terrain. After this, the remains of the drill cuttings are poured with cement and, after hardening, covered with sand and soil. This results in a burial site containing unneutralized drill cuttings.
- What determines the choice of technology?
The technology for disposal of drilling waste primarily depends on such factors as drilling technology (pithouse, pitless), equipment and machinery at the well pad, local conditions, availability of electricity, design of the mud pit, and requirements of environmental authorities.
At the same time, regardless of the combination of conditions, in practice, as a rule, not one, but several technologies are used.
- Can your Priroda-Perm enterprise process and dispose of drill cuttings and drilling fluids separately?
Yes, this technology is based on the removal of all waste to stationary technological complexes for processing and disposal of waste, where it occurs separate collection And further processing. On January 1, 2010, paragraph 7 came into force Federal Law dated December 30, 2008 “On production and consumption waste”, according to which it is prohibited to dispose of waste at sites not included in the state register of waste disposal sites.
For the processing of drill cuttings, the most common technologies are: thermal method, washing of pollutants, obtaining various products based on neutralized drill cuttings for recycling.
The technology for neutralizing spent drilling fluid and other liquid drilling waste is based on their purification from mechanical impurities and oil products and subsequent use for injection into a reservoir pressure maintenance system (RPM) or for the preparation of other process solutions.
- How do you prepare the water that returns back to the reservoir?
At our enterprise “Priroda-Perm” there is technology system processing of spent drilling fluid with disposal of prepared technical water into the well. A 4-stage system is used to clean spent drilling fluid and other liquid drilling waste. At the 1st and 2nd stages, the largest particles are separated in a sieve-hydrocyclone unit, at the 3rd stage, suspended particles are settled on a coagulation-flocculation unit using chemical reagents, at the 4th stage, the smallest suspended particles are separated with low specific gravity in a centrifuge.
After passing through all 4 stages, a process fluid is obtained, which can also be used for injection into the reservoir pressure maintenance system (RPM) or for the preparation of other process solutions.
- Does Priroda-Perm work in other regions or only in the territory Perm region? What companies do you work with?
We cooperate with many enterprises and companies, but if we talk about the largest ones, then in the Perm Territory they are LUKOIL and Eurasia, and outside the region they are Rosneft and TNK-BP. For several years now, a subsidiary of Priroda-Perm LLC has been operating in Udmurtia, successfully using the bioremediation method to restore oil-contaminated soils.
We are mastering a large volume of work in Orenburg region, it is too old district oil production and the problem of disposal of accumulated waste is very acute there. We recently received an extension license for Western Siberia, Tyumen region, Khanty-Mansiysk and Yamalo-Nenets district and the Komi Republic and are now preparing to work in these new regions for us.
Andrey Dmitrievich Maksimov,
Doctor of Economics, expert on environmental economics:
Today, the world has accumulated some experience in the neutralization and processing of drilling objects, but each company follows its own path. The British Petroleum company (Great Britain) uses the method of thermal dewatering of drilling fluids and Wastewater. In this case, smokeless burners are used, the productivity of which varies in a wide range from 142 to 8500 m 3 /day. gas
The German company KHD Humbold Wedag AG has proposed a technology for separating oil sludge into phases with subsequent combustion of the sludge. The installation is equipped with a device for collecting oil sludge, a vibrating sieve for separating the bulk of solid particles, a three-phase centrifuge, a separator for post-treatment of centrate from the centrifuge, and a furnace. The productivity of the installation is up to 15 m 3 /h for the initial oil sludge.
A problem arises - drill cuttings. To solve it, innovative methods, specialized technology and equipment are used. Technologies are being improved in this area to neutralize this dangerous substance. Disposal of drill cuttings is required by companies performing drilling, as well as by companies creating pits and tunnels.
What it is?
Drill cuttings are an aqueous suspension with a solid part, which consists of substances from the destruction of rock and borehole walls. The substance is captured in a slurry pipe during core drilling. It has 4 types of waste:
- spent bentonite;
- clay;
- liquid soil;
- groundwater.
High-quality disposal is necessary, since these products have a negative impact on nature. Enough to use effective method removal so as not to harm the environment.
Drilling is the impact of special equipment on soil layers, resulting in a well for the extraction of valuable resources. The work process is carried out in different directions, which are determined by the location of the soil or rock formation: it can be horizontal, vertical, inclined.
With the help of such work, a cylindrical void appears in the form of a straight trunk or well. The diameter may vary depending on the purpose, but it is less than the length parameter. The well begins on the soil surface. The walls are called trunks, and the bottom is called the bottom. After the extraction of valuable resources, various hazardous waste remains, which is important to dispose of correctly and in a timely manner. This will prevent negative impacts on the environment.
Harmful effects on nature
High-quality disposal of drill cuttings is an important task, since the environmental safety of Russia and the whole world depends on it. The penetration of this substance into water bodies can lead to pollution of the World Ocean.
The ingress of petroleum products causes a disturbance in the nitrogen balance of bottom soils, which disrupts the root system of aquatic plants. This is a violation of the ecosystem that affects the life of all living things in the reservoir and in nearby areas. Therefore, disposal of drill cuttings is necessary.
Classification
When disposing of drill cuttings, the classification of substances has important. Substances are divided according to quantitative and qualitative characteristics. To the most important properties include:
- Physico-chemical.
- Composition of solutions.
- State of aggregation.
The physical and chemical characteristics of the solution used for drilling are determined by the geological composition of the rocks being drilled and the tasks that the auxiliary components of the solution must perform. In addition to cooling and lubricating the tool, the wells involved make it easier to carry the drilled rock to the ground.
The solutions used consist of temperature stabilizers, surfactants, anti-foam additives, weighting agents specific gravity, fluidity enhancers. Based on these substances, a technology for recycling the solution is being created. In addition to inorganic components, the waste solution contains metals and paraffin deposits.
By state of aggregation solutions are liquid (high fluidity), semi-liquid and solid. The main property of the solution ratio is the percentage of solid and liquid phases.
- Up to 40 - fluid and liquid solutions.
- 40-85% - pasty and semi-liquid.
- From 85% - solid.
Disposal methods
There are various options for disposal of drill cuttings, but there is no universal method. The main ones include:
- Thermal. Elimination of waste by burning in special furnaces at high temperature.
- Physical. Thanks to centrifuge and focusing, the separation of liquid and solid, and then neutralization and disposal are carried out separately.
- Chemical. This drill cuttings disposal is done using chemical components. Solvents, clay, liquid glass and other reagents are also used. The substance is extracted to a solid form.
- Chemical-physical. A set of chemical reagents is selected that impart certain properties to substances. Then the components are processed in special equipment.
- Biological. Using this method, waste is processed by special microorganisms. This leads to the decomposition of sludge into substances that can be buried safely for nature. The advantage is the possibility of using the microorganism at the disposal and burial site.
Disposal of drill cuttings waste using such methods is considered safe. The appropriate option is selected based on the types of harmful substances.
Methods
Methods for disposal of drill cuttings are as follows:
- Injecting the mixture into underground formations.
- Application for obtaining mixtures that are useful in construction.
- Transportation to the disposal area.
Quality Standards
In addition to the disposal of used solutions and resulting sludge modern companies those performing such work must solve the problem of rapid liquidation. Another popular service is the liquidation of an old sludge pit located on the work site. The disposal of drill cuttings is in demand in Surgut, since the drilling industry is in demand in that area.
Benefits of recycling
Companies performing work in the field of ecology use their own transport and equipment with production, and also use their own technologies and equipment. They usually have landfills for waste disposal. It is such an organization that should carry out the disposal and processing of drill cuttings. She is responsible for the entire process, as well as for the consequences.
Some companies use the obtained substances to create building blocks, paving slabs, fake diamond and others Construction Materials. The resulting components are used in the construction and repair of roads, and the production of concrete. The solution with additional processing becomes suitable for reuse during drilling.
Almost complete processing of drill cuttings, solutions and slag is carried out. And there is almost no waste left. Besides environmental safety in the area where the work is being carried out, these activities are economically beneficial for the company. This is due to a reduction in the volume of tasks to eliminate sludge pits, as well as savings on fines imposed for environmental pollution and waste storage in the field area.
Difficulties of disposal
The problem of oil producing companies is considered to be the reluctance to pay for proper and safe waste disposal. The mixture of solid and liquid processing is placed in barns, and from there water is pumped out from paraffin-naphthenic hydrocarbons. The remaining sludge is poured with concrete and covered with soil.
As a result, burials appear where petroleum hydrocarbons are present, toxic substances, metals that combine with other components. An increase in the number of drilling rigs leads to the pollution of large areas.
The solution to the problem must be comprehensive. Therefore it is necessary:
- Tighten penalties for violations of Rospotrebnadzor requirements.
- Introduce effective systems for obtaining safe mass that can be buried or used for industrial purposes.
Thus, drill cuttings waste is harmful to nature. Timely and high-quality disposal helps prevent many problems. And for this, every oil producing company must treat its work responsibly.
Balaba V.I. Ensuring environmental safety of offshore well construction//Drilling and oil. - 2004. - No. 1. - P. 18-21. Relevance of the problem. During the construction of offshore wells, the main types of impact on the environment are emissions into the atmosphere, discharges into marine environment, its thermal and noise pollution. The volume and intensity of technogenic impact on the environment depends on the implemented well construction technology. Air emissions and noise pollution can be significantly reduced through environmental protection measures, and thermal pollution and the discharge of substances into the marine environment can be eliminated (“zero discharge” concept). Technological drilling waste. Drilling waste includes drill cuttings, waste drilling fluids and drilling wastewater. They are formed during the technological process of well flushing. Drill cuttings. During the process of deepening a well, drilled rock is formed at the bottom. During hydraulic transport of the drilling fluid from the bottom of the well to the surface, the rock, under the influence of technogenic factors, turns into drill cuttings. Therefore, using means for cleaning the circulation system of a drilling rig, it is not the drilled rock that is separated from the drilling fluid, but drill cuttings, which differ in volume and, which is especially important from an environmental point of view, in physical and chemical properties. The volume of drilled rock is equal to the volume of the wellbore. When designing, the volume of drill cuttings is approximately assumed to be 20% greater than the volume of drilled rock. Four factors can be identified that cause an increase in the volume of drill cuttings compared to drill cuttings: Well drilling is carried out for the most part in sedimentary deposits, in which clayey rocks are the most common. Their share is 65-80%. During hydraulic transport from the bottom of the well to the surface, drilled particles of clayey or rocks held together by clay cement are impregnated with the filtrate of the washing fluid and swell. The duration of residence of rock particles in the flushing fluid increases with the depth of the well and can reach several hours. The longer they are in the washing liquid, the greater their swelling. Solid phase particles of predominantly colloidal sizes from the washing liquid are adhesively attached to it. For change physical and chemical properties When turning drill cuttings particles into drill cuttings, they are affected by impregnation with the dispersion medium of the drilling fluid. The pores and cracks of the rock particles are filled with the dispersion medium of the flushing fluid, the surface of the clay particles is modified, on the outside and inner surface particles of drilled rock, substances of various natures are adsorbed from the dispersion medium of the drilling fluid. The mineralogical composition of drill cuttings is determined by the lithological composition of the rocks being drilled and can change significantly as the well deepens. Chemical composition The performance of drill cuttings depends both on its mineral composition and the properties of the drilling fluid. The particle size distribution of drill cuttings is determined by the type and diameter of the rock cutting tool, mechanical properties rock, drilling mode, properties of the drilling fluid and the efficiency of its cleaning. In table 1 shown factional composition drill cuttings and the rate of its deposition in the aquatic environment when drilling wells on the north-eastern shelf of Sakhalin (Sakhalin-1 Project) according to data.
Particle size, microns | Deposition rate, |
|
Fractional composition of drill cuttings and the rate of its sedimentation
in water environment when drilling wells on the northeastern shelf
Sakhalin
As follows from the analysis of the table, the fractional composition of drill cuttings varies within wide limits. It is important to emphasize that approximately 40% of the sludge mass is represented by particles smaller than 44 microns. As a result, at least two problems arise.
Firstly, such small particles are difficult to remove from the washing liquid by mechanical cleaning means.
With repeated hydraulic transport of drill cuttings particles through the well, they are dispersed even more. Effective chemical cleaning is necessary to remove fines.
Secondly, as the size of particles decreases, the rate of their deposition in the aquatic environment slows down (Table 1). Consequently, when washing liquid or sludge is discharged into the marine environment, its turbidity will persist for a long time.
Thus, when assessing the environmental safety of well construction, it is necessary to analyze the properties of drill cuttings, and not the drilled rock.
Spent drilling process fluids.
During the drilling process, in addition to flushing fluid, other process fluids are used, for example, buffer and perforation fluids. After use, they completely or partially become waste. Most of the waste produced is spent drilling fluid (WDF). Its volume corresponds to the volume of flushing fluid at the time of completion of well drilling. However, during the drilling process, an excess of drilling fluid may form, for example, due to accumulation in clay deposits when replacing one type of drilling fluid with another. In this case, the BPZ is formed directly during the drilling process.When assessing the impact on the environment, the subject of consideration, as a rule, is only waste washing liquids, which is methodologically incorrect.
Drilling wastewater.
The main sources of drilling wastewater (DWW) are washing of the drilling site and equipment, and the equipment cooling system. Reducing the volume of waste water is achieved by reusing them in the technological process (for example, for preparing washing liquid) after clarification in chemical and mechanical cleaning units. In this case, the volumes of water consumption and wastewater disposal are reduced.During the drilling process, excess drilling fluid, as well as spent drilling fluid, are separated into solid and liquid phases, which allows the latter to be disposed of as part of waste water. Therefore, the total volume of waste water includes the liquid phase of excess and waste washing liquid.
Well testing process waste.
These are waste fluids for inducing influx and killing the well, as well as fluids (formation water, oil, gas) obtained during testing. The gas coming out of the well is flared.Environmental friendliness of drill cuttings.
The environmental hazard of drill cuttings is determined by:toxic effects;an increase in water turbidity, which disrupts the vital activity of juvenile fish, planktonic and benthic filter-feeding organisms;physical impact on benthic organisms.One of the serious aspects of the problem is toxic effects on organisms. Currently, when assessing the environmental friendliness of drill cuttings, the main attention is paid to the gross content of mineral components. However, it is important to know in what chemical form the mineral components are present in the sludge. It has been proven that mobile forms are the most dangerous chemical substances, which determine the degree of toxicity and danger of drill cuttings. They are established in ammonium acetate buffer extract (pH = 4.8).
A fairly widespread point of view is that “... trace metals in sludge are in an insoluble form (usually in the structure of the crystal lattice of minerals) and their content (with the exception of barium) varies within the natural variability of the geochemical background of trace elements in bottom sediments.”
In table 2 presents the results of studies of aqueous and buffer extracts of drill cuttings (DS) from well No. P-1 of the Yuzhno-Pestsovskoye gas condensate field in the Tyumen region, carried out at the Research Institute of Human Ecology and Environmental Hygiene of the Russian Academy of Medical Sciences. A.N. Sysina [Z]. It has been established that in buffer extracts there is a significant excess of the maximum permissible concentration for soil for the main metals: chromium - 71 times, manganese - 33, cobalt - 3, nickel - 11, copper - 14, zinc - 84, lead - 122 times.
In aqueous extract | In buffer extract |
|
Aluminum | ||
Beryllium | ||
Tungsten | ||
Manganese | ||
Molybdenum | ||
Strontium | ||
Quantitative elemental analysis of aqueous and buffer extracts
drill cuttings
In table 3 presents the results of a study of the content of mobile forms of heavy metals in BS oil fields Nizhnevartovsk district of the Tyumen region according to data. Samples of sludge buried in sludge pits in 1970-1995 and 1996-1999 were studied. As can be seen from the table data, the content of mobile forms of heavy metals C pf exceeds the maximum permissible concentration for fishery reservoirs (MPCr.x.). It is important to note that the content of heavy metals in the 1970-1995 BS is higher than in the later one (1996-1999). This indicates that mobile forms of substances are washed out of the cuttings and drill cuttings are a source of secondary pollution. In addition to heavy metals, the studied BS samples contained petroleum products - 10600-147400 mg/kg in samples from 1970-1995 and 77-5950 mg/kg in samples from 1996-1999.
Component | BS samples | BS samples |
||
C pf, mg/kg | With pf / maximum permissible concentration r.h. | C pf, mg/kg | With pf / maximum permissible concentration r.h. |
|
Manganese | ||||
not determined | not determined |
Of course, the above research results are important for analyzing the consequences of exposure acid precipitation when burying drill cuttings on land. However, to assume complete inertness of the sludge dumped on sea bottom, without sufficient justification, in our opinion, should not be done. It must also be taken into account that drill cuttings may contain radionuclides.
Thus, drill cuttings are potentially dangerous for the environment, since they contain mobile forms of heavy metals, which, with prolonged exposure to them, sea water can be washed out, creating concentrations of toxicants exceeding the MPC.x.
Legal aspects of dumping technological waste drilling into the marine environment.
Environmental legislation is extremely inconsistent regarding the regulation of marine pollution. Its basic requirements for quality protection aquatic environment, set out in the Water Code of the Russian Federation, boil down to the prohibition of the discharge into water bodies of wastewater that is not treated in accordance with established standards, including those containing substances for which MPCs have not been established.Federal Law “On internal sea waters, territorial sea and adjacent zone Russian Federation“The burial of waste and other materials, as well as the discharge of harmful substances is prohibited. However, it contains incorrect language regarding the discharge of harmful substances or wastewater containing such substances. Releases of harmful substances resulting from exploration, development and related processing processes at sea are excluded from the ban. mineral resources internal sea waters and territorial sea.
Regulatory documents adopted before the introduction of these federal laws also allow the discharge of harmful substances into the sea.
A complete ban on the discharge of even treated wastewater is established in order to protect against pollution and other negative consequences economic activity marine areas of special fishery value - spawning and wintering grounds for valuable protected fish species, as well as habitats for animal and plant species listed in the Red Book.
Despite this, the State Environmental Expertise does not consider the dumping of drilling waste a violation of the law.
It should be noted that in accordance with the federal laws “On the Continental Shelf of the Russian Federation” and “On Internal Sea Waters, the Territorial Sea and the Contiguous Zone of the Russian Federation” any intentional removal of waste and other materials from ships and other floating equipment, installations and structures is qualified as burial.
The issue of disposal of technological drilling waste has been clearly resolved only in relation to wells on the continental shelf. According to the “Safety Rules for Exploration and Development of Oil and Gas Fields on the Continental Shelf,” drilled rock must be disposed of in accordance with the well construction project and environmental protection requirements. This does not seem to be entirely justified, since waste disposal (underground or on land) can also be environmentally justified and economically feasible. The existence of different approaches to the protection of the marine environment in the territorial sea and on the continental shelf
Question legal regulation marine pollution is currently relevant in connection with the adoption of the Federal Law “On Technical Regulation”, which provides for the development of special technical regulations, including on environmental safety issues.
Technical aspects of the discharge of drilling waste into the marine environment.
To meet the requirements of environmental legislation, the circulation of the drilling fluid during the drilling process must be organized in a closed cycle. In this case, the circulation of the drilling fluid and drilling waste is limited by the circulation system of the drilling rig and the drilling waste disposal system. To organize a closed circulation cycle at the drilling stage, a riser column is installed under the direction at the wellhead, for example, a driving column, and drilling is carried out with circulation of the flushing fluid inside the riser column.However, when drilling wells on the Sakhalin shelf and in the Caspian Sea, a directional drilling method is used without creating a closed circulation system. In this case, spent drilling fluid and drill cuttings during drilling in a direction (approximately 50-100 m) are discharged into the marine environment.
In reality, well cleaning is only sea water not limited. Oil and gas wells have complex design with a nominal diameter of the first trunk interval, as a rule, 914.4 mm. The upper interval is composed of unstable rocks, which, when flushing the well with sea water, are destroyed with the formation of caverns. Therefore, the actual trunk diameter is approximately 15-25% larger than the nominal one. In the trunk of such large diameter It is difficult to create conditions for effective hydraulic transport of drill cuttings to the surface. To do this, you need to increase the speed of the upward flow of the washing liquid, or increase the holding capacity of the washing liquid, in other words, thicken it.
The use of the first method is limited by the maximum performance of mud pumps. As a rule, the speed of the upward flow of drilling fluid in an open hole does not exceed 0.1 m/s. Using the second method means refusing to wash with sea water. Since in the absence of a riser column this is impossible, since it contradicts
clause 4.2 of GOST 17.1.3.02 77, then in the detailed design for the construction of a well it is indicated that flushing is carried out with sea water, and periodically (usually after 10 m of penetration) a portion (pack) of viscous liquid is pumped in order to clean the wellbore from cuttings. So, to flush the well, a combined flushing fluid is used, consisting of portions of sea water and a viscous liquid sequentially pumped into the well.
When drilling wells in the Caspian Sea, a clay suspension is used, on the shelf of the Sea of Okhotsk - a clay suspension thickened with polymer (approximately 75 kg/m
3 clay powder and 3 kg/m 3 polymer). In this case, fine clay particles and polymer are discharged from the well into the marine environment.When constructing wells in the Caspian Sea, the volume of a viscous fluid pack is 20 m
3 . Consequently, when drilling along a direction 50 m long, 80 m will be dumped into the sea during four pumpings. 3 washing liquid with sludge. The washing liquid used consists of bentonite clay powder 70 kg/m 3 (according to OST 39-202-86 may contain free soda from 1.0 to 5.0 g/100 g and M g О from 2.5 to 8.0%), caustic and soda ash 1 kg/m 3 and barite 113 kg/m 3. Thus, in those dumped into the sea 80 m 3 The washing liquid, in addition to sludge, contains 5600 kg of fine clay, 160 kg of caustic and soda ash and 9040 barite. Flushing is carried out at a total productivity of mud pumps of up to 80 l/s.Discharge of technological drilling waste continues at the stage of well casing. To ensure descent and subsequent cementing of the direction, the wellbore is filled with flushing fluid. Thus, when constructing wells in the Caspian Sea, the barrel is filled with clayey flushing fluid, weighted with barite to a density
1160 kg/m
Thus, the discharge (disposal) of drilling process waste occurs at all stages of drilling and casing the first interval of the well and should be taken into account when assessing the environmental impact of the construction of offshore wells.
Literature
1. Instructions for environmental protection when drilling oil and gas wells on land (RD 39-133-94). - M.: Rosneft, 1994.
2. Patin S.A. Oil and the ecology of the continental shelf. - M.: VNIRO, 2001.
3. Balaba V.I., Kolesov A.I., Konovalov E.A. Problems of environmental safety of the use of substances and materials in drilling. - M.: IRC Gazprom
, 2001.4. Mikhailova L.V., Rybina G.E., Akatieva T.G. Environmental hazard of drilling waste in oil-producing areas of the Tyumen region // Protection of aquatic biological resources in conditions of intensive development of oil and gas fields on the shelf and inland water bodies Russian Federation/Collection of materials from the International Seminar. - M.: Economics and Informatics, 2000.
Removal, processing and disposal of waste from hazard classes 1 to 5
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In solving this non-trivial problem, big role is devoted to the introduction of innovative methods, the use of specialized machinery and equipment, as well as the constant improvement of technologies to neutralize drill cuttings.
The main consumers of sludge disposal services are oil drilling companies - engaged in horizontal directional drilling and construction companies - engaged in digging pits and tunnels.
Harmful impact on the environment
Professional sludge disposal, the most important task on which the environmental safety of not only Russia, but also the rest of the World depends. Because drill cuttings and its release into individual large bodies of water are fraught in the future with pollution of the entire World Ocean. The entry of petroleum products into a reservoir greatly disrupts the nitrogen balance of bottom soils, resulting in disruption of the nutrition of the root system of aquatic plants.
Such a violation of the ecosystem affects the life of absolutely all living beings and microorganisms of the reservoir and surrounding areas.
Classification
- When solving the problem of drilling cuttings disposal, it is of no small importance to divide them into classes in accordance with quantitative and qualitative characteristics. The most significant signs are: Physico -.
- Chemical properties
- Composition of components included in solutions.
The physico-chemical properties of the solution used in drilling depend on the geological composition of the rocks being drilled and the tasks that the auxiliary substances of the solution must perform. In addition to cooling and lubricating the tool, solutions used when drilling wells perform the task of facilitating the removal of drilled rock to the surface of the earth and many other tasks that help to perform various additives in drill cuttings.
Various temperature stabilizers, superficial - active substances, anti-foam additives, weighting agents of specific gravity, fluidity enhancers and other components are included in the composition of the solutions used, and on the basis of these data the technology for recycling the solution is built. In addition to inorganic substances, the spent solution necessarily contains various metals, as well as paraffin deposits that fall into the solution during the process of driving a tool through the formation and oil - in the case of drilling oil and gas wells.
According to their state of aggregation, solutions are divided into liquid - with high fluidity, semi-liquid and solid. The main property of the relationship of a solution to one of the types is the percentage ratio of the solid and liquid phases of the solution.
- When the ratio of solid to liquid phase is up to 40%, solutions retain their fluidity and are recognized as liquid.
- The presence of a solid phase of 40 - 85% makes them pasty or semi-liquid.
- Solid phase over 85% is typical for waste solid type (rocks and waste sludge).
Disposal methods
In practice, waste generated during well drilling is disposed of in several ways. However, there is no universal processing method, although there is heated debate among experts on this basis.
Main methods used:
- Thermal. Disposal of produced sludge by burning it in special furnaces at high combustion temperatures.
- Physical. Using a centrifuge and focusing, the liquid and solid fractions are separated, then they are neutralized and disposed of each separately.
- Chemical disposal. Using chemicals, solvents, clay, liquid glass and some other reagents, drill cuttings are extracted to a solid state.
- Chemical - physical disposal. For each type of drilling fluid and cuttings, a specific set of chemical reagents is specially selected, giving the waste a predetermined physical properties. Next, the components obtained as a result of such processing are processed using special equipment.
- Biological disposal method. When using this method, drilling waste is treated with special microorganisms. The activity of these organisms decomposes drill cuttings into substances that can be safely buried for the environment. Another advantage of this method is that microorganisms can be used directly at the site of disposal and disposal of sludge (for example, at the site of liquidation of sludge pits left behind by drillers).
Quality standards for recycling services
In addition to the disposal of used solutions and resulting sludge, a modern and dynamically developing company providing such services must also solve the problem of emergency response to oil spills. Another service that is no less in demand on the market is work to eliminate the old sludge pit left at the work site.
Economic and environmental benefits from recycling
A modern company providing environmental services uses its own vehicles and special equipment during production, uses its own technologies and equipment, and very often owns its own landfills for disposal of neutralized waste. It is such an organization that must carry out the entire complex of work from beginning to end and bear full responsibility both for the current result and for the long-term consequences.
Many companies use the obtained components to produce building blocks, paving slabs, artificial stone and other building materials.
The resulting components are widely used in the construction and repair of roads, as a layer filler and in the production of concrete. The liquid phase of the solution, after additional processing, is reused during drilling. Thus, almost complete processing of drill cuttings, solutions and extracted slag is carried out, with an almost complete absence of waste. In addition to ensuring environmental safety in the regions where work is carried out, these activities provide good economic benefits to the company. This is due to the fact that with the introduction of high environmental standards in production technologies, the volume of tasks for eliminating sludge pits is significantly reduced, and this is not counting the huge reduction in fines for pollution ecological environment
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