Reactant-activation impact has broad potential application. RAI-NTS less limited to deposit's geological characteristics, technical operating conditions, reserves depletion degree than most of the known methods of enhanced oil recovery. Oil recovery index high rates and duration of enhanced oil recovery effect is achieved even in highly watered and mature fields in low-permeability reservoirs, and under low reservoir pressures. RAI-NTS is also successfully used during the wells development, in particular for producing wells efficient transfer into injection category.
Specific examples of RAI-NTS realization are provided below.
The successful development of injection wells with obtaining injectivity planning values after transferring them from producing category - is one of the common problems that RAI-NTS helps to solve efficiently.
In injection well №XX33 unsuccessfully tried to increase injectivity after its transfer from the Petroleum Fund. Multiple bottom hole treatments (acid treatments) were ineffective and well injectivity did not exceed 50 m3 /day at wellhead pressure of 258 atm. Injectivity falling noted up to 20 m3 / day within three months after the next acid treatment.
Injectivity increased to 258 m3 / day despite the fact that the injection was conducted from water-supply well by limited supply pump and wellhead pressure does not exceed 10 atm.
Along with increasing injectivity of the injection well, production wells rates have increased significantly (wells №№ХХ31, ХХ32 and ХХ37).
According to the results of an independent expert evaluation* additional cumulative production on this block was 36.756 ths. tons of oil. The positive effect was observed after the treatment more than 17 months.
Yuzno - Priobskoe oilfield is complex object for development from geological point of view. Formation permeability may arrange units mD. As a result, the average oil recovery factor in Yuzno - Priobskoe oilfield is about 0.28. On three injection wells of this object RAI-NTS technology has been successfully applied and showed 100% success to increase injectivity.
Before treatment well №XX733 for a long time worked with injectivity below 20 m3 / day. All attempts to increase injectivity were unsuccessful. Wellhead pressure, increasing up to 210 atm. did not lead to any result.
After conducted treatment in the early 2013 (see. diagram below) well №XX733 injectivity reached 154 m3 / day at wellhead pressure less than 210 atm. Thus, wellhead pressure during the entire period observation over treatment effect was in the range of 200 - 210 atm. The positive effect lasted more than 16 months.
As part of the pilot works on Yuzno- Priobskoe oilfields besides №XX733 well, two more injection wells have been processed, revealing the low-permeability formations. All three treated wells were recognized by the Customer with 100% success.
Over 13.5 months 2000 tons of incremental oil was produced. By the time of counting results the effect has been continuing.
One of the most common problems of oilfields in the late stage of development - producing wells high water cut. At this stage virtually any bottom-hole zone processings as hydrochloric acid treatments, mud-acid treatments and others - have low efficiency due to flooded-out regions around producing wells. Using methods substantially increasing drainage area (such as hydraulic fracturing, powder generator of pressure, etc.) is also limited due to high risk of water breakthrough into producing wells on newly created fractures.
RAI-NTS provides an effective solution to this problem. With RAI-NTS technology in work is involved previously not drained deposits without creating a man-made fracturing in a reservoir, thereby allowing to reach oil production increase without the risk of drowning.
Section of injection well №X63 in Vakhskoe oilfield has been selected for treatment with an average water cut of producing wells surrounding more than 75%.
At first stage of RAI-NTS technology realization, injection well was treated. After treatment, the well injectivity increased from 130 m3 / day to 260 m3 / day at a constant injection pressure. As a result of field geophysical tests after treatment profile injectivity increased from 9.9 m to 14.1 m - id est. on 42%.
Injectivity profile expansion positively affected on the surrounding producing wells. Displacement front from the treated injection well, reaching a production well X52, has led to an increase in oil-production rate there on 25% (by reducing the water-cut on 3%). Pressure rise down the hole also was seen.
In responding well №X52 was also carried out treatment, after that oil-production rate has increased more than 2 times.
The duration of a positive effect on injection and producing wells was more than 14 months, and incremental cumulative oil production on section deposit exceeded 3,300 tons during this period.
Thus, RAI-NTS technology has allowed involving in the development previously not drained reservoir areas on a section deposit with a high water cut and increasing oil recovery index for a longstanding producing field.
* – Independent scientific assessment was conducted by the Center of Petroleum Computer Technologies, under the supervision of Professor A.A. Kazakov from Russian State University of Oil and Gas.