RU2243366C2 - Method for acoustic treatment of wells of system for preservation of bed pressure - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes prior cleaning of face by washing with water with surfactant until getting pure well liquid. Acceleration profile is determined. In well-adjacent area calculated amount of active technological liquid is forced on basis of soluble surfactants and forced into bed, ultrasound emitter is lowered into perforation zone. Dispersing of colmatants is performed by effecting well-adjacent bed area by ultrasound frequency field in environment of technological liquid. Effecting by field of resilient oscillations is performed by steps in downward direction or upward direction with one meter step and effect time on step from 0.5 to 2.0 hours dependent on loss of well acceleration from project value. Calculated volume of acid is forced. Acid is forced into bed by triple volume of water relative to acid volume. Products of destruction are forced into bed. After acid dissolves dispersed colmatation sediments launch of well is performed for water forcing. Forcing of calculated volume of active technological liquid is performed with tubing pipes lowered to pit-face, and these are not extracted. Before determining acceleration profile and lowering ultrasound emitter into well tubing string is raised above bed ceiling.

EFFECT: higher efficiency of maintenance.

2 cl

Description

The invention relates to the oil industry and, in particular, to methods for developing oil fields with the maintenance of reservoir pressure (RPM) by water flooding. These methods are aimed at increasing the final oil recovery, as a rule, by redistributing hydrodynamic flows in reservoirs that are heterogeneous in permeability. The problem is solved by limiting water inflow into well-drained and water-washed interlayers by means of injection of flow-deflecting screens, hydrophobic filters in production wells with agents of various chemical and physical composition into the reservoir through the wells of the reservoir pressure maintenance system (PPD). Such types of work are carried out with the aim of preventing water breakthroughs into production wells from RPM wells and reducing the water content of produced fluid (Improving the efficiency of water injection wells. Overview. VNIIOENG, series "Oilfield", M., 1982, No. 22 (46) , 34 p .; The use of chemical reagents for the intensification of oil production. Handbook. M., 1991, S. 46-72.

Modern methods of enhancing oil recovery and new technologies in the fields of the Russian Federation. Oil industry, No. 10, 1993, with. 6-15). The application of the described technologies makes it possible to solve such problems as limiting water inflow to production wells from a specific well of the RPM system, increasing or decreasing the injectivity of RPM wells, leveling their injectivity profile to displace oil from weakly drained interlayers of a productive formation, and cleaning the bottom-hole formation zone (PZP) of production wells from mudding deposits of various nature and chemical composition to increase fluid flow.

In the practice of oil production at oilfields, it is not uncommon for the reservoir to use produced, waste or bottom water that has not undergone a sufficient degree of purification, and then the problem arises of blocking the bottom-hole zone of injection wells with mechanical impurities, residual organic oil emulsions, and pipeline corrosion products contained in the pumped water. This causes a sharp drop in water injection volumes up to a complete loss of injectivity of wells in the RPM system, which extremely negatively affects the dynamics of reservoir pressure (it drops) and production capabilities of production wells located in the zone of influence of these BPM wells. Clogging of the bottom-hole formation zone (PZP) of wells sometimes reaches such a level that traditional acid treatments of various types (well baths, acid drainage, acid shock), thermal and thermochemical treatments, injection of washing solutions of surface-active substances (surfactants), and even repeated perforation (as a rule, re-shooting) of the production casing of the well does not lead to restoration of the filtration properties of the bottom-hole formation zone (BHP) of the PPD wells.

One of the ways to increase the injectivity of wells in the RPM system is a known method of acoustic impact on the bottom hole of these wells in the environment of active process fluids. This method of developing oil fields (RU 2136859 C1) is taken as a prototype. The aim of the invention, taken as a prototype, was to improve the method of developing oil fields while reducing costs and increasing the environmental friendliness of the method by using a hydrophobic barrier with low phase permeability for water and high for oil in high-permeability sections and fractures of the bottom-hole zones of production wells, as well as alignment the injectivity profile of the wells of the RPM system using the setting of a flow diverting screen. To achieve this goal, we used water squeezing collating deposits destroyed by ultrasound into the reservoir.

However, at the moment, not the cost of well repair plays a decisive role, but the quality of work performed, i.e. achievement of the maximum possible overhaul period (MCI). Using the method taken as a prototype, it is possible to achieve an increase in the injectivity of wells in the RPM system and / or to equalize their injectivity profile.

However, upon reaching the goal (increase in throttle response) using this method, the effect is short-term, i.e. from several days to several weeks. This is explained by the fact that colmatating particles of various nature and composition introduced from outside the pumped water are not removed from the well, do not dissolve, but are mechanically crushed and forced through the pumped water into the formation zone farther from the well in an ultrasonic field. Thus, during the start-up process, the injection reservoir after injection after the acoustic impact during the overhaul, the injectivity of the well increases. When crushed colmatating particles penetrate into the far zone of the formation and are deposited, the injectivity drops, and the injectivity profile of the PPD well is leveled due to the redistribution of the volume of injected water between other layers. Thus, the goal is the redistribution of the injectivity profile of the wells of the RPM system is achieved, and the increase in injectivity is only partially, which is the disadvantage of this method.

Another disadvantage of the method taken as a prototype is the neglect, for the sake of reducing the cost of technology, of the work associated with pre-cleaning the borehole of the BPD from contaminants introduced with pumped water and partially settled in the borehole, by flushing the bottom of the wells with water, ennobled with various surfactants, to a clean borehole liquids.

All organic and inorganic clogging deposits according to the prototype method are dispersed (crushed) and pressed into the formation to create a hydrophobic filter that acts as a limiter of water flow into the production well or flow-deflecting screen in the wells of the RPM system. However, far from all cases of RPM well repairs, installation of flow-deflecting screens is required, i.e. decrease in injectivity in well-drained and washed interlayers. As a rule, the inclusion of weakly drained and stratified interlayers is required.

Another disadvantage of the prototype is the establishment of optimal parameters of ultrasonic exposure to the bottomhole zone based on preliminary laboratory tests at various frequencies, intensity and time of ultrasonic dispersion of the precipitate selected from the bottom zone in a particular process fluid, providing a dispersion with a particle size of solid phase within 0.5 -20 microns - paragraph 5, column 7 of the patent prototype. The implementation of this item in the field in practice is extremely difficult or impossible. Determining the optimal frequency of exposure to the clogging material is possible only in laboratory conditions. When the acoustic effect on the bottomhole formation zone through the perforations of the well casing and sufficiently low radiation powers (from 0.7 to 1.5 kW) is exerted, the acoustic effect is not on the formation rock (matrix), as the authors of the prototype suggest, but on the well fluid. Wave oscillations are transmitted by fluid through the pore space of the formation, exerting a wave effect on deposits on the walls of capillaries. Thus, it is enough to achieve the frequency of ultrasound in a narrow frequency range (for example, 18-24 kHz), at which the cavitation effect occurs, as in a pore space filled with an active process fluid (ATF) based on water-soluble surfactants, the effect of a wave "washing machine" is manifested (Ultrasonic technology. - M.: Metallurgy, 1974, S. 285-293, Ultrasonic technology, issue 2, 1963, S. 52-57).

This effect does not depend on the chemical properties of the rocks that make up the reservoir, but is directly dependent on the intensity of the energy radiated into the well fluid, its frequency, porosity, permeability and absolute permeability of the rock.

Acoustic technologies have a fairly clear boundary of application for the indicated physical parameters of the layers.

Therefore, before applying the ABC method, it is necessary to analyze the physical characteristics of the productive strata of the wells (data are available in field business files) to eliminate useless work and increase the success of its use.

One of the most important areas of well overhaul (KRS) of the RPM system is to increase the injectivity of poorly drained interlayers and restore lost injectivity in order to increase the oil displacement coefficient. Taken as a prototype method (RU 2136859 C1) allows you to partially solve the specified problem, however, it is ineffective in the repair of wells of the RPM system with a complete loss of their injectivity.

The purpose of this invention is to improve the method of developing oil fields with maintaining reservoir pressure by water flooding by means of better repair of wells in the RPM system, which is expressed in achieving and (or) increasing injectivity with equalizing the injectivity profile of wells that have completely lost it and increasing the length of the wells overhaul period.

The technological result is achieved in the process of implementing the method according to the following scheme:

1. Analysis of the physical parameters of the reservoir.

2. The undercut of tubing to the bottom of the well.

3. Flushing the wellbore with a refined 0.1-0.2% surfactant (type ML-81B, neonol AF _9-12 , etc.) with water until a clean wellbore fluid.

4. Lift tubing above the "roof" of the reservoir by 20-30 m

5. The descent into the well of a geophysical instrument and conducting geophysical well surveys (GIS) in order to determine the injectivity profile of the well and "bind" the tip of the geophysical (KG) cable to a certain perforation interval.

6. Ascent from the well to the surface of the geophysical instrument.

7. The lowering of the tubing string to the "bottom" of the reservoir.

8. Injection and pushing into the reservoir of the estimated amount of a water-soluble 1-5% surfactant solution, leaving at least 25% surfactant solution in the wellbore or leaving ATZ in the form of a bath in the absence of injectivity.

9. Secondary lifting of the tubing string above the “roof” of the formation by at least 20-30 m.

10. Descent into the perforation zone of the ultrasonic emitter on the geophysical cable and stepwise acoustic exposure in the frequency range 18-24 kHz to the perforation zone in the ATZ medium with a step of one meter (in the direction from top to bottom or from bottom to top) and exposure time in steps of 0, 5 to 2.0 hours, depending on the degree of loss of injectivity of the well from the design value.

11. Rise to the surface of the acoustic emitter.

12. An allowance for tubing to the “bottom” of the formation.

13. Injection of the calculated amount of 12%, corresponding to the parent rock of the productive formation of the acid, and pushing it into the formation with a volume of water triple to acid.

14. The dissolution of acid dispersed by ultrasound colmatating deposits within 4 hours.

15. Starting a well for injection of water.

In this technological scheme, there are no labor-intensive full tripping operations (STR) for extracting tubing from the well, which, in turn, leads to a reduction in the time and cost of repairing the well. The implementation scheme of the method, including standard well repair operations, has the form ATZH + ABC + Acid, and has no analogues among known prototypes (patents RU 2094594 C1, RU 2015874 C1, RU 2055979 C1, RU 2151273 C1).

Claims (2)

1. The method of acoustic impact on the wells of the reservoir pressure maintenance system, including injecting into the well the calculated amount of active process fluid based on water-soluble surface-active substances (surfactants) when the tubing is lowered to the bottom, dispersing colmatants by acting on the borehole zone formation by an ultrasonic frequency field in an active process fluid medium based on water-soluble surfactants launched by an ultrasonic emitter lowered into the perforation zone and the next sale of degradation products into the reservoir, and well start-up under water injection, characterized in that prior to injecting the calculated amount of active process fluid based on water-soluble surfactants into the well, they are pre-cleaned by flushing the bottom of the treated surfactant with water to a clean well fluid, the injectivity profile is determined, after injecting the calculated amount of active process fluid based on water-soluble surfactants it is forced into the reservoir, while the impact on the borehole zone of the formation by the field of elastic vibrations of ultrasonic frequency is carried out in an active process fluid medium based on water-soluble surfactants with an ultrasonic emitter step by step in the direction from top to bottom or bottom to top with a step of one meter and exposure time in step of 0.5 to 2.0 hours, depending on the loss the injectivity of the well from the design value, after which the calculated amount of acid is pumped, and the acid is pushed into the formation with a volume of water triple with respect to the acid, then the dispersion is dissolved after the acid Fat th e bridging carried start water injection wells, the tubing from the well is not removed to the surface, and before determining the injectivity profile and descent in the area of perforation is carried sonotrode pripodem tubing above the roof of the producing formation. 2. The method according to claim 1, characterized in that in the absence of injectivity of the formation, the injected active process fluid is brought through the tubing to the formation and left in the wellbore in the form of a bath.