US20150218911A1

US20150218911A1 - Device for decolmatation of the critical area of exploitation and injection wells

Info

Publication number: US20150218911A1
Application number: US14/431,909
Authority: US
Inventors: Anna Vladimirovna Abramova; Maya Vladimirovna Bayazitova; Andrei Andreevich Pechkov; Yury Alekseevitch Saltykov
Original assignee: OBSCHESTVO S OGRANICHENNOI OTVETSTVENNOSTJU "VIATECH"
Current assignee: OBSCHESTVO S OGRANICHENNOI OTVETSTVENNOSTJU "VIATECH"
Priority date: 2012-09-18
Filing date: 2012-09-18
Publication date: 2015-08-06
Also published as: WO2014046560A1; CA2888203A1; EA201400646A1

Abstract

The device for the decolmatation of the critical area of exploitation and injection wells includes a generator of electromagnetic pulses of resonant frequency, which is equipped with a controller (not depicted), and a coaxial cable which connects the generator to a downhole instrument, in which at least two converters for converting electromagnetic energy into mechanical energy are arranged, the converters operating at different frequencies. Furthermore, the converters for converting electromagnetic energy into mechanical energy are arranged in the downhole instrument in series in order of decreasing resonant frequency, and the dimensions of each of the converters are determined by the magnitude of the resonant frequency, each of which differs from the previous one by an integer of octaves. Furthermore, the cable which connects the generator of electromagnetic pulses to the downhole instrument is coaxial with a wave impedance which is equal to the output impedance of the generator and the input impedance of the downhole instrument.

Description

The invention is in the field of oil production, specifically cleaning of the bottom-hole area using ultrasound energy.
To ensure efficacious utilization of wells, it is necessary to remove paraffin and asphaltene deposits on the collectors' pore walls, because their accumulation leads to a decrease in the bottom-hole area's permeability which in turn causes a decrease in the yield of the well and, on some occasions, completely precludes utilization of the well.
Prior art knows theoretical rationalization of a method of acoustic treatment of the bottom-hole area for the purpose of its decolmatation (O. L. Kuznetsov, E. M. Simkin, G. Chilingar, “Physical foundations of vibration and acoustic treatment of oil-and-gas reservoirs” M. Mir, 2001, pp 106-116); however, said rationalization does not contain a detailed description of a device for decolmatation of the bottom-hole area.
Prior art knows a method and a device for removal of paraffin plugs from produced oil using ultrasonic waves (U.S. Pat. No. 7,264,056) comprising placement of at least one device generating ultrasonic oscillations near oil-well tubing, and a device generating variable frequency oscillations outside the oil well. The device emits (preferably in a concomitant manner) ultrasonic oscillations in three fixed frequencies in the range of 10 kHz-2000 kHz. Moreover, the first frequency oscillation causes production tubing to vibrate and, as a result of that, paraffin plugs are dislodged from the tubing's walls. Second frequency oscillations disrupt the connections that hold together paraffin molecules, thus splitting them into smaller particles, and third frequency oscillations split long alkanes into shorter molecules.
Prior art knows a method to clean oil-wells and water wells (patent RU No. 215 1273) that is based on removal of colmatants by periodically applying elastic vibration to the space near the well, comprising preparatory evaluation of geological, geophysical, and hydrodynamic information about the production well and the data on the major-parameter dynamics during utilization of the production wells in a given deposit; determination of the mode of treatment; treatment of the selected production intervals of the bottom-hole area with an elastic vibration field with pre-set parameters; correction of treatment modalities based on monitoring the speed of colmatants' removal from the bottom-hole area; and determination of efficacy of the applied treatment as judged by an increase in the production yield, changes in the fluid movement profile, and other parameters of the production well, characterized in that during the preparatory evaluation of the major-parameter dynamics while using the well in a given deposit, productivity, water-cut, oil-gas ratio, bottom-hole pressure, and deposit pressure are measured and analyzed during the well's use; based on said analyses, wells are selected for which a decrease in the yield is due to colmatation of the bottom-hole area in the production deposits with preservation of high deposit pressure; and for each deposit in these wells, the following parameters are determined: the mode of treatment comprising treatment intervals, the pace of treatment, the frequency and the intensiveness of elastic vibrations, and the order of continuous or pulse-type treatment over various intervals; moreover, using the curves reflecting a decrease in the yield, the sequence of the treatments is determined for various wells with a consideration of the extent to which the yield is decreased, and the data obtained in the course of assessing the efficacy of the performed treatment is used to adjust the mode of the well's utilization.
Prior art knows a method of acoustical treatment of a bottom-hole area of a production deposit (patent RU No. 2026969) comprising applying an acoustic field onto the zone near the well, characterized in that, in order to increase productivity of the deposit by means of restoring filtration properties of its bottom-hole area, the filtration properties of the bottom-hole area are measured prior to the deposit's treatment; areas with low filtration properties are identified; and the deposit's treatment is carried out in a consistent, point-by-point manner in the up-down direction by multiple rounds of subjecting the bottom-hole area sites with low filtration properties to an acoustic field whose intensity is at least 0.2 W/cm²; moreover, following each treatment round, filtration properties are measured, the dynamics of their restoration are determined and, based on the results of said determinations, intensity and duration of the acoustic treatment are increased until the filtration properties are stabilized.
Prior art knows a method (patent RU No. 2296215) of treating the bottom-hole well area—employed in the capacity of a prototype—comprising lowering into the well's perforation interval, on a column of oil-well tubing, a setup consisting of a packer, a paired sucker-rod pump with a body comprising an upper and a lower body connected by a perforated duct, a column of spears with a plunger, and an ultrasound generator; separating inter-tubing space above the perforation interval by the packer; applying ultrasonic-frequency elastic vibrations to the bottom-hole area of the well in the medium of active technological fluid and acid solution; suctioning off reaction products with simultaneous washout of treatment products; treating the deposit with ultrasound; and creating alternating motion of the fluid in the perforation interval and weak depression pulses, characterized in that a mechanical ultrasound generator is used as an ultrasound generator that works when a stream of liquid passes through it in one direction while the ultrasonic treatment is carried out when the liquid is supplied into oil-well tubing by the pump during the fourth part of the pump's cycle.
The known methods and devices feature low efficacy of decolmatation of the bottom-hole area of production wells, and their manufacture and utilization are complex.
The goal to be achieved with the invention being claimed is to create a device that is able to increase the efficacy of treatment of the bottom-hole area using the minimally possible dimensions of the down-hole apparatus.
The invention being claimed achieves said goal by placement, in the down-hole instrument, of no less than two converters of electromagnetic energy into mechanical energy that work at different frequencies. Moreover, the converters of electromagnetic energy into mechanical energy are positioned in a down-hole instrument sequentially in the order of decreasing resonant frequency, while the size of each converter is defined by the resonant frequency magnitude, and each subsequent frequency differs from the previous one by the whole integer of octaves. Further, the cable connecting the generator of electromagnetic pulses and the down-hole instrument is coaxial with wave impedance equal to the output impedance of the generator and the input impedance of the down-hole instrument.

A suggested schematic of the invention “A device for decolmatation of the bottom-hole area of production and injection wells” is shown in FIG. 1, where 1—ultrasound converters of electromagnetic energy into mechanical energy; 2—bottom-hole area; 3—perforation zone; 4—down-hole instrument; 5—oil-well tubing; 6—casing pipe; 7—well; 8—coaxial cable; 9—winch; 10—generator of resonant frequency electromagnetic pulses with a controller (not shown for clarity); 11—geophysical lifter.

The device operates as follows (see FIG. 1).
A signal of the corresponding frequency from generator 10 equipped with a controller (not shown for clarity) passes via coaxial cable 8 to converters of electromagnetic energy into mechanical energy 1. Using ultrasound with a higher frequency ensures maximally intensive treatment under conditions with small radii, whereas ultrasound with a lower frequency allows for coverage of a broader volume of the bottom-hole zone. Moreover, the generator's controller (not shown for clarity) forms a signal of the required shape, which is harmonic with stepwise enveloping. In this case, each of converters 1 is tuned to the specific harmony of the overall signal. Converters of electromagnetic energy into mechanical energy 1 are positioned in down-hole instrument 4 sequentially in the order of decreasing resonant frequency, while the size of each converter is defined by the resonant frequency magnitude. Each subsequent frequency differs from the previous one by the whole integer of octaves. Coaxial cable 8 features wave impedance equal to the output impedance of generator 10 and the input impedance of down-hole instrument 4, thus ensuring that the target shape of the signal is maintained.
It has been demonstrated experimentally that multi-frequency treatment afforded by the invention being claimed, significantly increases the yield of wells when compared to mono-frequency treatment (see Table 1).

TABLE 1

Average increase in the yield following multi-frequency
and mono-frequency ultrasonic treatment of the well's bottom-
hole area

Average	Average	Average
yield,	yield,	yield,
1-10 tons/	10-30 tons/	>30 tons/24
24 hours	24 hours	hours

Terrigenous deposits

Mono-frequency	50-70%	10-25%	5-10%
treatment
(frequency: 25 kHz)
Multi-frequency	70-110%	25-45%	8-15%
treatment

Carbonate deposits

Mono-frequency	30-50%	15-25%	3-8%
treatment
(frequency: 25 kHz)
Multi-frequency	40-70%	35-50%	5-10%
treatment

Thus, the invention being claimed allows one to significantly increase the depth of the efficacious treatment of the bottom-hole area with the minimally possible dimensions of the down-hole instrument.

Claims

1. A device for decolmatation of the bottom-hole area of production and injection wells, comprising a generator of electromagnetic pulses of resonant frequency and a coaxial cable connecting the generator to a down-hole instrument, wherein, in order to increase the depth of the efficacious treatment of the bottom-hole area, the down-hole instrument contains no less than two converters of electromagnetic energy into mechanical energy; moreover, the signal sent from the down-hole instrument's generators to the converter of electromagnetic energy into mechanical energy is harmonic with stepwise enveloping, and each of the converters is tuned to the specific harmony of the overall signal.

2. The device of claim 1, wherein the converters of electromagnetic energy into magnetic energy are positioned in the down-hole instrument sequentially in the order of decreasing resonant frequency, while the size of each converter is defined by the resonant frequency magnitude, and each subsequent frequency differs from the previous one by a whole integer of octaves.

3. The device of claim 1, wherein the generator of electromagnetic pulses is equipped with a controller that enables one to form a signal with the required shape.

4. The device of claim 1, wherein the cable is coaxial with wave impedance equal to the output impedance of the generator and the input impedance of the down-hole instrument.