SU1645460A1 - Method and composition for plugging of rocks - Google Patents

Abstract

The invention relates to the drilling of oil, gas and geological exploration wells, the mining industry, engineering construction. The purpose of the invention is to increase the efficiency of cementing by increasing the strength of the crystalline stone and its resistance to erosion and dissolution by flushing and formation fluids. A highly concentrated aqueous solution of salt is pumped into the rocks, for which a highly concentrated aqueous solution of soda ash is used, with soda ash and water taken at the following ratios, wt%: soda ash 25.9-37.5; water the rest. Under field conditions, for preparing the mixture, soda ash is dissolved in a separate container formed with a pump or cementing unit in water preheated to 20-25 ° C. The dissolution of the soda is accompanied by heat and the temperature rises to 40-42 ° C, which allows the maximum amount of soda to be dissolved. After cooling the salt solution in the formation, a crystalline stone is formed, the strength of which, as well as the erosion and dissolution resistance of flushing and formation / fluids, are higher than those of the known ones. 3 tab. (I f-sp sp e

Description

The invention relates to the drilling of oil, gas and exploration wells, the mining industry, engineering construction, and in particular to methods and compositions for isolating permeable formations in low-temperature wells, strengthening unstable rocks and inconsistent soils.

The purpose of the invention is to increase the efficiency of cementing by increasing the strength of the crystalline stone and its resistance to erosion and dissolution by flushing and formation fluids.

The method of cementing of rocks consists in pumping into them a highly-concentrated aqueous solution of

which use an aqueous solution of soda ash, containing not less than 25.9% soda. Under field conditions, the plugging mixture is prepared in the following sequence. For example, in a separate container bound with a pump or cementing unit, 1, 8 tons are dissolved in 3 m of water (62.5 wt.%).

(37.5 wt.%) Soda ash. Water is preheated to (20-25) C with the help of steam from a boiler house or electric heating elements. Dissolution of soda goes with the release of heat and the temperature of the prepared solution reaches (40-42) ° C. The maximum amount of salt dissolves at this temperature.

The upper limit of the concentration of calcified soda was determined by the stabilization of indicators on erosion and solubility of crystalline stone in water, the lower limit was determined by erosion values of the cement stone and the amount of filtrate after crystallization in comparison with the analogue. Thus, the optimal concentration range of soda ash of plugging compositions is in the range of 25.9-37.5 wt.%. The results are presented in table 1.

The method of cementing rocks is carried out as follows.

To isolate permeable formations

in low temperature wells, the prepared plugging mixture is pumped through a hydromechanical or drilling packer installed above the permeable zone in order to ensure its minimum dilution with flushing fluid in the well upon delivery to the formation. The initial temperature of injection of the mixture into the reservoir is determined by calculation using the method of AN Nerban. and in case it exceeds the temperature of the prepared solution, the plugging cociaB is additionally heated.

To fix the unstable rocks in the wellbore, the plugging mixture is pumped through the drill pipe and placed opposite the range of doused or unstable rocks. The work logs provide for above and below a pack of tamping mixes to disperse the buffer hardening fluid that prevents inhHeBHorw from mixing the main implant with the drilling fluid in the well.

To consolidate unbound soils, the prepared plugging composition is pumped through special perforated pipes plugged into the soil or small wells.

PRI me R. In 100 g (74.1 wt.%) Of water heated to (20-25) ° C, 35 g (25.9 wt.%) Of soda ash is dissolved. Stir with a laboratory mixer until all soda has dissolved. After rastenium, the temperature of the salt solution reaches (40-42) ° C. The time of dissolution and mixing is 5-7 minutes. The heated solution in a glass beaker is placed in a WATER bath with flowing circulation of tap water for cooling and crystallization. The time of cooling of the plant, crystallization and strengthening of the structure in the experiments performed was 24 hours. After that, the obtained crystal stone samples were subjected to erosion and solubility tests.

Table 2 shows the strength characteristics of various bulk soils when they are plugged with the proposed method. Table 3 presents data on the solubility of crystalline stone of soda ash in drilling fluid and formation fluid.

Chemical reagents, devices, research methods used for laboratory and experimental research are reflected in the act of laboratory tests.

The use of the proposed method and composition will increase the efficiency of cementing operations by increasing the strength of the crystalline stone, increasing its resistance to erosion and dissolution by flushing and formation fluids, as well as expanding the scope of application as compared to the known.

Claims (1)

Invention Formula The method and composition of the cementing of rocks by pumping into them a heated highly concentrated salt solution, characterized in that, in order to increase the efficiency of the tamponj by increasing the strength of the crystalline stone and its use 516454606 resistance to erosion and dissolution of an aqueous solution of salt is used with water-washing and formation fluids, an aqueous solution of soda ash, as a highly concentrated containing not less than 25.9% salt. Properties investigated plugging compositions 62.5 62.5 62.5 62.5 62.5 Sifted sand with dimensions of 10.8 measures 0.5-1 mm Gravel finely grained with sand 160 (sand particle size 0.5-1 mm) Dolomite crushed with a length of 1800 measures 2-10 mm Crushed argillite with dimensions of up to 420 mm T and L and C I Spreadsheets 12.0 8.4 5.6 19.9 11.3 In water 137,562.5 50.442.6 35.8 20.5 7.1 In brine 237,562.5 51.143.8 37.0 25.3 10.8 1.7 In brine Siaofita 337,562.5 50.849.9 49.2 48.5 44.5 40.3 38.5 35.1 31.8 30.5 29.6 29.1 28.8 In produced water 437,562.5 49.850.9 51.1 52.0 51.7 51.2 50.3 49.9 49.1 48.5 48.0 47.5 46 25 28 thirty