RU2229015C2 - Method for elimination of intensive absorption - Google Patents

Abstract

FIELD: well construction technology. SUBSTANCE: method includes lowering of filling column with a generator of hydroacoustic waves mounted on its lower end, preparation of backfill compound, pumping and forcing through of backfill compound into absorbing layer. During pumping and forcing through, compound is dispersed by hydroacoustic waves. Well is then seasoned for a period of concrete consolidation. According to the method, as backfill compound gel-concrete solution is used. Its pumping and forcing through is performed with effect of hydroacoustic waves with vibration frequency of 10³...16•10³ Hz and with amplitude of pressure oscillations up to 6 MPa. Generator of hydroacoustic waves is mounted on pumping line before cementing head and/or on lower end of lowered filling column with a through packer placed above it. EFFECT: lesser time and material costs. 2 cl, 1 tbl

Description

The present invention relates to the oil and gas industry, in particular to the processes of well construction, and can be used directly to eliminate the intensive absorption of drilling and grouting solutions.

There is a way to eliminate intense absorption by installing a bridge of non-hardening clay-cement paste, which is formed during the simultaneous injection of cement and clay mortars through a column of filling pipes into the reservoir.

The disadvantage of this method is the high probability of a sharp increase in the structural and mechanical properties of clay-cement paste inside the column of casting pipes, significant pressure losses during the injection process and, as a rule, the inability to use the method with a large depth of the absorption horizon. With an increase in the length of the column of casting pipes, the probability of the formation of a non-pumpable plug during the injection of the mixture increases significantly. In addition, when using this method of eliminating intense absorption, the installation of a fixing cement bridge is required (Krylov V.I. Isolation of absorbing layers in deep wells. M .: Nedra, 1980).

Closest to the proposed method is a method of eliminating intensive absorption of drilling and cement slurries, including lowering a casting column into the well with a sonar generator installed on its lower end, preparing a plugging composition, injecting and selling the plugging composition into the formation, and dispersing it during the pumping and selling process with the influence of hydroacoustic waves, exposure of the well to the waiting period for cement solidification (RF patent No. 2039210, published on July 9, 1995).

The disadvantage of this method is the insufficient impact of hydroacoustic waves on the plugging composition, a low degree of dispersion and relatively high mobility of the composition under conditions of an absorbing formation and, as a result, a high probability of poor-quality isolation of the formation.

The purpose of the invention is the reduction of time and materials in the elimination of intensive absorption of drilling and cement slurries by forming a highly viscous structured hardening screen in the bottom-hole zone of the wellbore and the absorbing formation, which is formed as a result of dispersion of the cement-cement solution by pumping it through a hydraulic generator of hydroacoustic waves, and, as a result , improving the quality of isolation of the absorbing horizon.

This goal is achieved by a method of eliminating intensive absorption of drilling and cement slurries, including the descent of a casting column into the well with a sonar generator installed on its lower end, the preparation of the plugging composition, the injection and delivery of the plugging composition into the absorbing layer, and its dispersion during the injection and delivery process sonar waves, holding the well for a period of waiting for the cement to harden, according to the invention as a plugging composition Ava use gel-cement solution, the injection and sale of which is carried out when exposed to hydroacoustic waves with a frequency of 10 ³ ... 16 · 10 ³ Hz and an amplitude of pressure fluctuations of up to 6 MPa, and a hydro-acoustic wave generator is installed on the discharge line in front of the cementing head and / or at the lower end of the descent casting column with the passage packer located above it.

The method is as follows. The bottom of the casting column is equipped with a generator of hydroacoustic waves, for example, with a toroidal or axial vortex chamber (see AS USSR No. 1538584, class E 21 B 33/14, 1986, AS USSR No. 1826580, class E 21 B 33/16, 33/14, 1990). The column is lowered to a depth of 1 ... 2 m above the bottom of the well. A plug composition is prepared at the wellhead — a cement-cement mortar with normal parameters according to GOST: a density of 1500 ... 1550 kg / m ³ and a viscosity measured in units of spreadability of the AzNII cone of 18 ... 21 cm. In this case, the following ratio is maintained in the prepared composition: ingredients, wt.%:

bentonite clay powder 3-7

cement Portland cement 40-43

setting accelerator 0.5-2

plasticizer 0.1-0.5

water technical rest

Gel-cement mortar is injected into the well and forced into the absorbing layer. When pumping a dispersed gel-cement solution through a generator of hydroacoustic waves, a number of hydroacoustic effects arise, the most important of which is cavitation. Under the influence of hydroacoustic cavitation, clay micelles and hydrated particles of cement are destroyed, as a result of which the specific surface of the particles of the dispersed phase in the gel-cement solution increases and, as a result, its structural and mechanical properties increase, water separation and shrinkage during hardening decrease. In this case, the spreadability of the cement-cement solution along the cone of the AzNII decreases to 11 ... 13 cm. In this case, the cement-cement solution fills the near-wellbore space in the absorbing layer and the bottomhole zone of the well, loses mobility and quickly sets.

The table shows the test data of the generator of hydroacoustic waves with toroidal and axial vortex chambers during the injection of a cement-cement mortar into the well during cementing of the production string.

Under the influence of vibrations with a frequency of 10 ³ ... 16 · 10 ³ Hz and a pressure amplitude of up to 6 MPa, hydrated cement particles and clay micelles are oriented in a certain way and compacted, which leads to an increase in the sedimentation stability of a cement-cement mortar, an increase in the strength of a stone, and an improvement in adhesion cement with rock. In addition, under the influence of hydroacoustic waves, the conditions for the penetration of a highly viscous gel-cement solution into the pores and cracks of the absorbing layer are improved. In this case, at the end of the sale and the termination of the influence of waves, the cement-cement mortar quickly loses its mobility. The setting time of the cement-cement mortar is regulated by the addition of an accelerator chemical agent. The curing time of gel cement is determined by the moment of setting of the samples taken during its mixing. The strength of the stone formed during hardening is quite sufficient for high-quality insulation and at the same time, when drilling a bridge, it does not contribute to the deviation of the drilling tool from the previously drilled direction, which often happens when using a quick-setting mixture of normal density to eliminate the catastrophic absorption (1800 ... 1900 kg / m ³ ) based on Portland cement.

To conduct a hydrodynamic study of the absorption zone, depending on the geological and technical conditions of the well drilling, as well as to improve the conditions for filling the pores and cracks of the absorbing layer with a highly viscous gel-cement solution, a pass-through packer is installed above the sonar wave generator in the layout of the casting column. In this case, the filling pipes with the hydro-acoustic wave generator and sealing device are lowered into the well, the annulus is sealed, the absorbing layer is examined in various modes, and then the cement-cement mortar is dispersed and structured under the influence of hydro-acoustic waves, then the well is left to be pumped. for the period of waiting for the solidification of cement (OZZ). The use of a through packer in this case will increase the selling pressure of the plugging composition in the under-packer zone without the risk of hydraulic fracturing of overlying rocks and excessive increase in the height of the cement bridge. When hydrodynamic study of the absorbing formation, it is necessary to take into account the pressure loss in the hydraulic generator.

With a small depth of the location of the absorbing layer, it is possible to install a generator of hydroacoustic waves on the discharge line in front of the cementing head, and it becomes possible to control the parameters of the plugging composition before exposure to hydroacoustic waves and after exposure.

Thus, the proposed method allows to reduce the cost of eliminating intense absorption with good insulation quality, it is extremely simple in technological terms, reliable, does not require the consumption of scarce and expensive materials.

Claims (2)

1. A method of eliminating intensive absorption of drilling and grouting fluids, including lowering a casting column into the well with a sonar generator installed on its lower end, preparing a plugging composition, injecting and selling the plugging composition into the absorbing layer, and dispersing it with hydroacoustic effects during injection and delivery; waves, exposure of the well for the period of waiting for the solidification of the cement, characterized in that as a tamping composition using gel cement p target, download and which prodavku produce when exposed hydroacoustic waves with the frequency of their vibrations March ¹⁰ ... 16 × 10 ³ Hz and an amplitude of pressure fluctuations to 6 MPa, and the generator hydroacoustic waves set on injection line in front of the cementing head and / or on the bottom of flushing drilling columns with an upstream packer located above it. 2. The method according to claim 1, characterized in that the gel-cement solution is used in the following ratio of ingredients, wt.%: Bentonite Clay Powder 3-7 Grouting Portland cement 40-43 Setting accelerator 0.5-2 Plasticizer 0.1-0.5 Technical water Else