On the problem of increasing oil recovery - the methods of ultrasonic intensification, hydrodynamic studies, the purpose of application of ultrasonic technology

The problem of oil recovery increase is quite acute in continuous deterioration of resource base and small increments of oil reserves by new discoveries in most heavy-heavy oil and low-permeability reservoirs.

The majority of oil fields have entered a stage of development characterized by a reduced reservoir pressure, oil production and an increase in water production, as a result in many fields the vast majority of wells were converted for mechanized and repeatable operation.

Accordingly, all newly commissioned fields are usually hard-to-recover. Therefore, in many oil fields the production is now becoming less effective and requires changes in the system of development.

The high rate of stocks recovery in initial period of development is usually carried out under insufficient knowledge of the geological object. As a result of recoveries of different rates low-permeability areas are not involved in the development, and high-permeability areas are subject to premature flooding. Thus, hard-to-recover stocks are being formed actively.

Oil remaining in the flushed out areas and the substratum was transformed due to anthropogenic effect. In addition, the remaining oil in the reservoir undergoes negative impacts of hydrophobic interactions.

The heterogeneity of the reservoir properties, as in the section and along strike, results in uneven oil recovery and reduction of the rate of oil recovery by reservoir as a whole. In the process of a long-term operation of the well borehole a mudding of a space reservoir, which reduces the productivity of the well and working capacity of the perforation interval, which requires periodic cleaning of the near-well zone.

In the later stages of the field development, we are dealing with virtually new reservoir properties, new hydrologic, hydrodynamic, thermal and physical chemical regimes, with a changed composition of the reservoir fluids.

Scientific studies show that the later will be the adjustment of the system; the lower will be the results of production. In this case not only general technical and economic parameters deteriorate irreversibly, but also there reduces the value of economically viable extraction ratio compared with the potentially achievable with the use of new technologies. Possible loss of oil may reach 10% or more.

Under these conditions, the problem of increasing the efficiency of existing fields by providing the potential of each well, regardless of its service life arises urgent more than ever.

In principle, it is possible to solve this problem without significant material costs.

For example, methods of ultrasonic intensification.

In order to select boreholes of optimal parameters as to effects on near-wellbore reservoir zone it is necessary to carry out a complex of hydrodynamic study one of the main objectives of which is to determine not only the seepage of reservoir parameters, but also parameters and the state of the well bottom zone, significantly influencing the intensity of the flow reservoir fluid.

It is well known that the decrease in the permeability of the near-well zone of the reservoir is due to a number of fundamental factors:

1. Reduction of permeability of the near-well zone of the reservoir, due to the tangential annular compressive stresses that occur during drilling as a result of overburden pressure;

2. Deposition in the near-well reservoir area of solid phase of process liquids (killing, flushing, drilling fluids, etc.) and other solid residues.

3. Formation of plugs in the perforation holes due to the removal of rock particles from the formation, deposition of reaction products as a result of widely used treatments near-well zone of formation of chemical reagents and paraffin deposition.

4. Mudding of capillary system of the reservoir due to blockage of pore channels by colloidal disperse system, which forms a spatial grid.

Physical and chemical characteristics of the impact of these factors on the formation are different in nature.

If the first factor leads to a decrease in pore size in the near-well zone of the well and, consequently, to reduce the permeability, the second factor causing clogging of pores foreign body, a third factor causes blockage of perforations, the fourth factor also leads to a decrease in pore size.

These factors reduce the production of oil and capacity of wells.

Obviously, for the maximum effect in the choice of technology of oil production one should take into account these factors and, respectively, to look for the ways to eliminate their negative effects.

The use of ultrasound technology solves effectively most of these problems.

The ultrasound exposure leads to a set of complex, interrelated processes leading to the fact that compression waves, loading the porous medium cyclically, having reflected many times, are transformed into stress-strain waves, creating conditions for development of a network of cracks and microcracks, both in the walls of perforations, and in the adjacent reservoir rock.

The interaction of the acoustic field with the phases of the rock makes it possible to reach the following:

- increase of permeability due to changes in the structure of the porous space;

- destruction of the mineral salt deposits in capillaries;

- acoustic degassing and reduction of oil viscosity;

Ultrasound-modulated frequencies, passing through the reservoir can be included in operation both individual low-permeable and mudded interlayers and productive part of the whole reservoir ...

- high power ultrasonic vibrations can provide an effective cleaning of bottomhole formation zone regardless of the nature of mudding.

- ultrasonic vibrations effectively clean the capillaries near the reservoir area

- ultrasonic vibrations reduce the surface tension in the capillaries

- ultrasonic vibrations effectively destroy the salt formation in the capillaries

- ultrasonic vibrations effectively destroy colloid formations

Reconstruction of the potential productivity of production and injection wells is achieved by breaking down colloidal dispersed systems, clogging the near-well zone of the reservoir...

The technology provides the integrity of the production casing and a cement sheath behind it and the low costs of production works.

It uses small-sized mobile devices; the process of the impact is technically and physiologically safe and environmentally friendly.

The ultimate goal of application of the ultrasonic technology in oil industry is increase of profitability of exploitation of oil fields.

The technology allows, without prejudice to oil-bearing reservoir to achieve effectively the restoration of filtration properties of productive layers of with minimal time and material costs.

As a separate direction one can separate the use of the ultrasound technology as preventive measures carried out on a regular basis in order to maintain an optimal state of filtration properties of the reservoir and bottomhole formation zone.

Progress Industrial Systems SA (Switzerland) is a world leader in the design and manufacture of sonar systems for intensification of oil production.

Using the experience gained in the field of ultrasound technology and the experience of development of sonar systems for different operating conditions, the company has achieved great success in creation of powerful ultrasonic systems capable of operating at great depths and high temperatures.

At the moment, we have created a sonar system unparalleled in the world for intensification of oil production consisting of a powerful ultrasound generator in robust and tamper version and two ultrasonic emitters of different diameter, powered by a standard logging cable. All equipment implementing the technology of ultrasound exposure is compatible with standard equipment of geophysical parties that does not cause difficulties in mastering the technology by staff personnel.

Technical specifications:

Generator capacity: from 4500 to 12000 W

Operating Frequency: 20000 Hz

Emitters capacity: from 500 to 1200W.

Signal: sine, modulated, pulse.

Terms of use:

Maximum cable length: 5000 m, formation maximum temperature: 95° C maximum pressure in the bottom hole: 350 bar.

The equipment's effectiveness is proved by tests conducted in 2006-2008 in Russia in Severo-Iraelsk deposit and Sotchemyussk deposit.

in Romania, low-production fields of Vata, Tazlau, Baltani.

The tests were carried out in Russia under the auspices of the "Wells Logging" Department of Ukhta State Technical University, and in Romania for PETROM (OMV Österreich) oil company with the assistance of ATLAS GIP (Weatherford USA) Geophysical Company.

The positive effect of the filters cleaning was obtained at four (4) wells, increase in flow of fluid from the reservoir constituted 30-80%, which indicated an increase in the filtration properties and allowed not to stop the oil production for cleaning of filters by traditional ways.

Conclusion:

Restoration of oil production for recommended wells is from 20 to 350%. The effectiveness of the method after professional analysis and selection of wells is up to 90%.

Progress Industrial Systems SA is ready to offer you the most modern equipment to carry out ultrasonic stimulation of oil production.

The equipment provides a reagent-free, environmentally friendly, mobile way of increasing the productivity of wells, and helps to save material and human resources, to reduce the cost of oil. The particular effect of the method should be noted in extraction of heavy oil.

Progress Industrial Systems SA Company is continually upgrading equipment and tries to take into account all customers' wishes.

Registration

ок
forgot password?