December 1, 2008
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Home / Issue Archive / 2008 / June #6 / CAT Technology Sets a Benchmark in Improving Formation Acoustic Treatment Techniques

№ 6 (June 2008)

CAT Technology Sets a Benchmark in Improving Formation Acoustic Treatment Techniques

Given the fact that in the nearest years oil and gas will stay the most demanded primary power sources it is essential to maintain the high level of their production.

By V. Tokarev

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CAT Technology Sets a Benchmark in Improving Formation Acoustic Treatment Techniques

V. Tokarev

Given the fact that in the nearest years oil and gas will stay the most demanded primary power sources it is essential to maintain the high level of their production. Subject to the decrease of producing wells flow rates and the increasing development of the fields with complicated geological and production conditions the up-to-date Enhanced Oil Recovery (EOR) technologies are attracting more and more attention due to the various physical and chemical treatment techniques applied to pay zones.

Acoustic treatment (AT) technologies are the most promising among the CAT techniques providing for enhanced recovery of the valuable fluid without damage to physical and chemical properties of the reservoirs and well design, as well as ensuring environmental safety of the process. Despite of the theoretical development and wide acknowledgement of the AT methods even in the previous century, nowadays only we can speak about the real capability of their industrial application, when the rapid development and miniaturization of electronic components is observed.
Since 1998 Siberian-Urals Geological Company has been developing the hardware for the reservoirs’ acoustic treatment based on the scientists’ experience and technologies of the leading companies of our country. Today the company can offer to the interested users the Acoustic Radiating System (ARS) including a set of the downhole piezoceramic radiators and high performance surface generators embodying the technique of the Controllable Acoustic Treatment (CAT) of oil-and-gas and water-bearing formations.
The unique feature of the CAT technique is the application of a non-linear interaction of the waves of two adjacent frequencies within a multiphase non-linear environment that is a pay thickness. For this purpose the acoustic radiator is excited at two pumping frequencies within its pass-band. As a result a difference frequency is formed: it is equal to the dominant frequency of the environment, i.e. a frequency of the mechanical resonance of the porous layer consisting of the rock skeleton and filling fluid, as well as the resonances of the individual heterogeneity of the formation. Unlike monoenergetic acoustic radiation technique wherein the difference frequency oscillation penetrates the formation thickness achieving the maximum value near the source, in AT the latter is achieved some distance from the source making formation treatment more effective.
Besides, the availability of several wave radiation modes implemented with the CAT hardware set provides for flexible selection of the optimal parameters of the reservoirs’ treatment with regard to their basic properties and behavior in the course of treatment.
The singularity of the above ARS hardware is verified with the patent of the Russian Federation.
CAT technique is based on the application of a wide range of physical and physical/chemical phenomena developing within the rock and fluids contained in under effect of the ultrasonic fields.

CAT Technique and Hardware Enable:

To put into work both individual clogged and low permeable layers, and the entire pay thickness of the formation;
To ensure efficient cleaning of the formation pay zone and to increase its permeability regardless of the clogging sediments nature;
To treat producing wells without essential costs and time losses (total time of well preparation and treatment does not exceed 30 hours);
To apply acoustic capacity exceeding 5 W/sq. cm in downhole conditions;
To treat formation within a wide frequency range (11-45 kHz) increasing its efficiency drastically;
To provide for high concentration of the acoustic energy due to optimization of the radiator directional diagram;
To provide for optimal control of treatment modes due to the feedback in a downhole device – surface equipment communication;
To ensure high reliability of the hardware due to application of specially developed techniques, materials and accessories used in the course of the advanced equipment creation.
 CAT technique was applied to enhance profitability of oil and gas field operation in West Siberia, Urals, Tatarstan, the Republic of Belarus, gas and condensate field of the Republic of Komi and of oil fields in Serbia. Good results have been achieved in 80 percent of cases and average flow rate increased by 30 percent (and even up to 300 percent in a few cases) for the groups of treated wells.
For sure, CAT technology is not a complete alternative to other techniques of the borehole environment physical and chemical treatment; however application of various treatment regimes enables effective recovery of pay thickness filtration properties with minimal time and material costs, and without any damage of subsoil structures.
Note that CAT application in combination with some chemical treatment techniques gives the best result to compare with the effect of each individually applied method.
There are good grounds for believing that CAT technology can be used as a special preventive measure applied on a regular base to maintain optimal balance of the reservoir filtration and porosity properties. Pursuant to calculations, similar non-costly preventive measures are capable to give sufficient economic advantages to oil producing companies, which are actually interested in recovery enhancement of each producing well and in increase of effective operation life of the entire field.
Thus, creation, modernization and successful practical application of ARS complex verified with good results at a number of projects in Russia and abroad is considered as an important stage of acoustic treatment techniques development giving a real chance for future CAT technology application in a wide industrial range.

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