The problem of developing fields with high viscosity oils and bitumens became extremely relevant in the context of substantial rise in energy costs.

We offer a solution to the problem of integrated development of high-viscosity and low-grade oils and bitumens based on application of hydrogenation, solution and dilution of high viscosity hydrocarbons. These methods are combined with a wide use of coiled tubing and wave technologies, wave units with application of working agents able to dissolve, rarefy and wash hydrocarbons of the pay zones without the waste of the heat energy [1-3].

 

The historical background of the problem is the following. Back in 1930s professor Gubkin estimated that conventional methods of oil production won't be sufficient to recover more than 30-50% even of low-viscosity oil. For high-viscosity oil that figure is much lower. And though a number of highly effective methods of bottomhole zone and oil reservoir treatment have been developed since that time, the challenge of cost-effective production of bitumens, high-viscosity and low-grade oil still has to be met [3].

 

For now there are some well-known methods of oil production and recovery enhancement, which suggest heat treatment of oil rocks with various well constructions and technological decisions applied [4-9].

 

Yet the methods are not that efficient in the production of high-viscosity and low-grade oil because of substantial heat energy waste, low scope of thermal effect on the pay zone, low oil recovery factor, necessity in a dense network of production and injection wells, which makes the final product very expensive.

 

The technologies of pay zone heat treatment [10-11] imply simultaneous heat and wave impacts. The heat treatment is carried out by means of delivering a heat-transfer medium (superheated vapor) to the layer. The operation is produced by a generator of pressure variations set in the injection or production wells. The wave treatment is carried out in compliance with oscillation frequency calculated on the basis of the corresponding functions.

 

The disadvantages of the technologies are waste of heat energy on warming the pay zone, low oil recovery rates. It eventually results in high cost of produced oil. Besides, such methods don't exclude the cases of oil emulsions inrush into the water beds.

 

There is also another method used in mineral resources production. It includes the development of the reservoir with at least two wells, dissolvent supply through the injection well, pressure surge treatment with regularly changed wave shapes and unsymmetrical distribution of pulse energy in time of relatively zero amplitude and delivery of mineral deposits through the production wells [12].

The method is inefficient, since oil travel paths are often sealed during supply of water, acids  and other working agents. Some sections of the pay zone become unavailable for further production.

The inrush of oil-containing fluids to water beds is possible as well.

 

The other technology of permeability increase [10] envisages drilling-in and formation stimulation by the static pressure and elastic waves. The method implies the use of tubing with the waves direction changing by the reflector fixed in a certain position and a packer set up in the well in order to protect the production string and overlying zones from the impulse waves [13].

The technology is inefficient for the development of high-viscosity and low-grade oil and bitumens. There is also a threat of inrush of oil containing solution in the nearby water beds, which may disrupt the environmental balance in the production region.

 

Our technology advances the development of heavy hydrocarbons fields and preserves the ecological system at the same time. This is achieved by the pay zones stimulation with the formation treatment by static pressure and elastic waves with the help of the tubing. The waves are sent in specific directions from the reflector fixed in a certain position. After the packer is set in the well, coiled tubing drilling is performed in at least one injection and one production wells. Then they do the directional drilling of lateral wells with intervals between them, which are calculated taking into account the size of the field. Drilling to the calculated distance in both the injection and the production wells has to be made by the several wells, but at least three of them are obligatory:

The distance between the holes depends on permeability of the formation of the upper and lower contacts of the zone.

 

Before the development they use static pressure, directional elastic waves with calculated amplitude and working agents pumped through the perforated casing in order to treat the upper and lower contacts of the pay zone and seal this sections. The water and gas proof shields produced during this treatment don't let the oil containing emulsions, gases, hydrocarbons and/or other caustobioliths to leave the pay zone.

 

During development the supply of solvent into the injection well is accompanied by static pressure accompanied by the elastic waves sent into the necessary direction through the producing string. Such method provides the effective solution, hydration and gasification of viscous oil, bitumens and other caustobioliths and the complete coverage of the pay zone between the injection and the production wells. The production of the dissolved hydrocarbons may be carried out by means of vacuum treatment with the pressure changing in time.

 

Figure presents the technological schemes of developing the deposits of high-viscosity and low-grade oil, bitumens and other caustobioliths.

 

The suggested method of producing highviscosity and low-grade oils, bitumens and other caustobioliths includes the following operations.

 

The pay zone 2 within the field 1 is penetrated with at least one injection well 3 and one production well 4 oriented downward along the field 1. Additional highly deviated sidetracks 8 and 9 are drilled in each well. They are located in the rocks of the upper 5 and lower 6 contacts of the zone at the calculated distance from the medium line 7 of the zone.

 

The wells 8 and 9 are cased and perforated all along their length. The mouths of the injection and production wells are equipped with X-mas trees and units 10 for treatment of the pay zones 2 with elastic directional waves. Wave reflectors 12 are lowered on the producing strings 11 to the calculated depth.

 

The reflector 12 is set in the injection well 3 and oriented towards the production well 4 and the reflector in the production well 4 is oriented towards the injection well 3. Packer 13 is set up in the upper hole of the injection and production wells at the calculated distance from the reflectors 12. Then a linkage between the upper 8 and the lower 9 holes of the injection and production wells is made along the upper 5 and lower 6 contacts of the pay zone 2 by means of static pressure and the energy of the elastic waves directed along the channel produced by liquid agents with visco-elastic backfill systems that help the cementation of soft rocks. The amplitude of the directional elastic waves shouldn't exceed 0.7 % of the rock strength. It is also necessary to cut the time on linking the upper boreholes 8 of the injection well 3 and the production well 4 with their lower boreholes 9 from the production well 4 to the injection well 3.

 

To this end counter pressure of tensile waves is produced until the calculated injectivity rates of the upper 5 and lower 6 contacts of the pay zone 2 are reached and the working reagent containing visco-elastic backfill systems appears from the production well 4. Thus, water and gas proof shields appear to create a confined space 14 for the fluids of the pay zone 2 with its further development and maximum level of recovering viscous oils, bitumens and other caustobioliths in formation conditions without waste of heat energy and driving light distillates from the pay zone 2.

The method also allows preserving the environmental balance in the field of operations. With additional injection and production wells drilled, the confined space 14 may shelter a system of gradual recovery of high-viscous and low-grade oil, bitumens and caustobioliths. The recovery will be made with the methods of solution, hydration, changing of the aggregate state etc. Gas containing layers with predominant methane accumulation will be formed in the worked-out sections.

 

The recovery of high-viscous and low-grade oils, bitumens and other caustobioliths from the pay zone 2 begins with lowering a reflector of directional elastic waves 12 into the middle borehole 15 of the injection well 3. The reflector is lowered with the producing string 11 and oriented to the necessary direction along the pay zone 2. After that a packer 13 is opened. After assembling the equipment facilities the injection well 3 is filled with working substance so that the pay zone 2 could be treated with the directional elastic waves. Depending on the composition of high-viscosity and low-grade oils, bitumens and other caustobioliths, the working agent may include a mixture of saturates and/or alkenes (Н2, СО2), water Н2О and other components in the proportions necessary for maximal recovery of the mineral resource.

 

A wave source 10 is also filled with the working agent. An air or gas cushion is blown off to the atmosphere by means of a special flap. The pressure of the liquid on the mouth is fixed in such a way so that there was a balance between hydrostatic pressure of the working agent column in the hole 15 and the pressure of the rocks, which prevents the formation fluids and the working agent from leaving the confined space 14 formed by the impermeable layers.

 

During the wave treatment of the pay zone a static balance between the rock pressure and the pressure of the working agent column in the borehole 15 on the reflector 12 is maintained.

The treatment of the pay zone is oriented towards the production well 4 with the amplitude of elastic waves being no higher than 0.7 of the formation elasticity.

When the wells 3 and 4 are linked  and the first portion of the dissolved high-viscosity and low-grade oils, bitumens and working agent from the production well 4 is received, the tensile waves start radiating towards the injection well 3. The technological process is continued till the necessary volume of the mineral and the working agent is obtained.

 

In order to provide the hydration of high-viscosity and low-grade oil, bitumens and other viscous caustobioliths in pay zone conditions a downhole hydrogen generator may be lowered by the tubing 11 to a certain point in the well.

 

The proportions of saturates, alkenes and gases, including Н2 , СО, СО2 etc. depend on the reservoir conditions, characteristics of the minerals and development stage of the pay zone 2.

 

The existing world technologies of converting natural oil into the gasoline are based on the assumption of self-sustainability of oil composition, impossibility or unprofitability of enriching it with hydrogen, irrationality of using carbon from natural resources, unavoidable concomitant production of inferior products like masut, maltha and coak.

 

Nevertheless, an ideal hydrocarbon fuel that can be obtained from oil is isooctane gasoline C8H18 .

 

It enables the highest gasoline heating effect of 11000 Kcal/kg and high degree of environmental friendliness during the combustion. The highest heating effect of motor gasoline produced in Russia is 7000 Kcal/kg. It brings about low efficiency of the engines and high level of pollution.

 

In terms of its composition properties as a material for gasoline production, oil doesn't have enough hydrogen for the production of an ideal gasoline. It is necessary to add 40% of hydrogen to the high-grade oils and 80% to the low-grade ones.

 

We offer technologies and equipment for allround preparation and refining of low-grade viscous oils and bitumens for production of high-octane motor gasoline. They include the implementation of the new technological processes based on the new principles of enriching of natural oil with hydrogen and equipment for production of gasoline with basic characteristics, which are very close to ideal gasoline.

 

On the first stage the recovered mixture is prepared with sulphur, sulfides and mechanical admixtures removed. Then the crude is turned into a hydrocarbon emulsion consisting of the fine associates.

On the second stage the hydrocarbon emulsion is turned into isooctane gasoline with 98% output.

 

The core of the process is an integrated effect of resonant hydrodynamic cavitation and wave fields on the mixture. The process breaks the hydrocarbon chains of the mixture components and produces free radicals ОН- and Н- from the carbon-bearing additive. As a result free radicals ОН- and Н- and broken hydrocarbon chains produce stable associates of the hydrocarbon emulsion in the cavitation area. Their density is 0.75- 0.82 g/sm3. The emulsion is rather stable and can't be broken in a mechanical way and even if the temperature rises up to 100-120°С. The continuous treatment of the components with low frequency wave field followed by the treatment with high frequency wave field allows receiving a high quality hydrocarbon emulsion suitable for direct procession at the operating refinery without changing its technological processes. The obtained hydrocarbon emulsion is chemically inert during contacts with metal walls of hydraulics and pipelines.

The industrial experiments testing hydrodynamic wave dispersers produced more than thousand tons of emulsion for procession at the refinery.

 

The emulsion doesn't fall into the components and the output of light oil during heat distillation rose from 30-45% (crude oil) to 80-85% (emulsion).

 

The stability and quality of produced hydrocarbon emulsion allows transporting it without damage to its basic characteristics in tank capacities for long distances or supplying it into pipelines.

Our equipment and technologies provide for minimal energy consumption during the refining of hydrated high-viscous low-grade oils, bitumens (low-grade hydrocarbon crude material) and make a good product. The equipment may make part of a delivery system without updating technical equipment at the refinery.

 

The equipment and technology for turning the emulsion into the isooctane gasoline provides generation of high-intensive acoustic radiation in the flow of the refined material with the calculated amount of hydrogenous additive. The resonant high frequency oscillations generated at cavitation have high power density providing for high degree of dehydrogenation under reasonable crude heating, not higher than 150°С. The synthesis of the end product (for example, isooctane gasoline) is made under high frequency wave action, when the individual atoms and free radicals of the destroyed structure and added hydrogen atoms combine.

 

The equipment for isooctane gasoline production may be made mobile. The main equipment units may be installed in containers and used right on the site of bulk plants or at the producing field.

 

True competition between the producers of motor fuel is possible only under the condition of equal or lower costs of production of high-octane gasoline with better production and ecological characteristics.

 

Isooctane gasoline, produced from natural high-viscous, low-grade oil and bitumens with the suggested methods have low costs, don't contain sulphur and other harmful contaminants. Plus their combustion is usually complete.

 

Apart from the mentioned advantages, isooctane gasoline has the highest combustion temperature, low percentage of nitrogen oxides and coal smut in the exhaust air.

 

Thus, the hydration of low-grade hydrocarbons into isooctane gasoline and then in a motor fuel right on the site of oil recovery provides the economic production at small fields, saves transportation and procession costs, offers competitive, ready-to-use and environmentally friendly oil products.

 

The suggested technology for producing and refining low-grade hydrocarbons has several advantages as compared to other methods:

1. This is a non-waste industry offering solution to social and environmental problems. It guarantees complete oil refining and manufacturing of a wide range of environmentally friendly products.

2. High profitability.

3. The production can be set up and start to operate in 2-3 years.

4. The production provides itself with the necessary amount of power and heat. Its surplus may be used for the development of the oil production area or sold to the population or organizations.

5. The economic efficiency is provided by low-cost production of motor fuels, power and heat energy.

6. The technologies are based on the use of standard equipment, produced mainly in Russia, and typical engineering structures.

 

Coiled tubing technologies together with the opportunities for permeability increase or for sealing areas of formation fluids and working agent leakage with the help of the power of controlled shockwaves provide an economical and ecological solution for development of high-viscosity and low-grade oils, bitumens and other caustobioliths.

 

New strategy of high profitable production and refining of heavy hydrocarbons completely lifts the necessity in big plants for producing isooctane gasoline, which has a good potential on the market of motor fuels.

 

1. Wave Treatment of Oil and Gas Pay Zones / V. S. Voitenko [and oth.]. - Minsk: Yunipack, 2005. - 250 p.

2. Coiled Tubing: Basics and Experience of Implementation in Mining / V.S. Voitenko [and oth.]. - Minsk: Yunipack, 2007. - 584 p.

3. Arens, V. Zh. Physical and Chemical Geotechnology / V. Zh. Arens. - М.: Publishing House of Moscow State Mining University, 2001. - 656 p.

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6. Patent: Russian Federation №2082875, МПК Е21В43/00, 1997.

7. Patent: Russian Federation №2114289, МПК Е21В43/24, 1998.

8. Patent: Russian Federation №2191895, МПК Е21В43/24, 2002.

9. Patent: United States №5215149, МПК Е21В43/00, 1993.

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13. Patent: Republic of Belarus 2815, МПК: Е21В43/28, Е21В43/25, 1999.