SU1177455A1 - Method of monitoring the process of dissolving of colmatation phenomena in wells - Google Patents

Description

The invention relates to the operation of groundwater intakes, wells vertical drainage and systems of artificial replenishment of groundwater, and more specifically to methods of controlling the process of dissolving clogging formations of the well.

The aim of the invention is to increase the productivity of the well by increasing the accuracy of the control.

The method is as follows.

In the well filter, the calculated amount of hydrochloric acid is injected, a heat source of constant intensity is installed and a temperature sensor is installed, after which the heat source is turned on. During the heating of hydrochloric acid, the temperature of the solution is measured.

With a constant flow of thermal energy, the temperature of the solution rises until the intensive dissolution of the dehydrated calcifying formations, represented by iron oxide and hydroxide, begins. Their crystal lattices have the appropriate energy that must be expended for its destruction. With intensive dissolution of clogging formations with a solution with an elevated temperature, thermal energy is spent not only on heating the solution, but also on the destruction of the crystal lattices of the colmatant, which causes a certain decrease in the temperature of the solution, detected by the temperature sensor. After the end of the process of dissolving dehydrated clogging formations, the temperature of the solution begins to rise, since thermal energy is again spent mainly on heating the solution. In this case, the secondary temperature increase may be relatively small, since the solution gives off some of the heat to the environment, and some of the heat is spent on the process of evaporation of water. At the time of the beginning of the secondary rise in the temperature of the solution, the treatment is stopped and the well is pumped.

Example 1. A well with a depth of 29 m and a diameter of the casing 8 captures water-saturated fine-grained sands. It is equipped with a mesh filter with a length of 10 m and a diameter of 4 ^{| (} installed in flush. During the operation period of 13 years, due to chemical clogging processes, the well was disconnected from operation as anhydrous. The initial specific flow rate of the well is 1.5 m ³ / h.

550 l of sodium bisulfite solution of 8% concentration with stabilizing additives of phosphates is pumped into the well filter and an electric heater is installed

Type TEN in acid-resistant performance with a power of 7.5 kVA, a temperature sensor connected with a cable to the type Sh69000 logometer. After turning on the heating element, the temperature is measured and the solution is sampled to analyze the dissolved iron. The iron content in the cooled samples is determined after processing by the photocolorimetric method. ,

In tab. Figure 1 shows the change in the temperature of the solution and the concentration of dissolved iron during the thermoreagent treatment of the well.

The secondary temperature rise begins at the 110th minute, at the 120th minute, the treatment is stopped and the well is pumped out.

After treatment, the flow rate of the well is 9 m ³ / h at a decrease of 6 m, the specific flow rate of the well is determined to be 1.5 m ³ / h.

The stabilization of dissolved iron concentrations begins at the 110th minute, as is the secondary rise in the temperature of the solution, which indicates stabilization of the permeability of the filter zone, i.e. about the most complete improvement of the hydraulic characteristics of the filter zone at a given processing mode and the advisability of stopping processing.

Example 2. A well with a depth of 37.7 m and a casing diameter of 8 "captures water-saturated silty sand. It is equipped with a mesh diameter of 4", 9 m long, installed flush. During the operation period of 13 years, due to chemical clogging processes, the well was disconnected from the operation as anhydrous. The initial specific flow rate of the well is 0.76 m ³ / h.

584 l of aqueous 8.8% sodium bisulfate solution with stabilizing phosphate additives are completed in the well filter and an electric heater of the heater type of 7.5 kVA, a temperature sensor connected with a Sh69000 logometer is installed. After switching on the heating element, the temperature of the solution is measured and the solution is sampled for analysis of dissolved iron. The iron content in the cooled samples is determined after processing by the photocolorimetric method.

The measurement results are presented in table 2.

The secondary temperature rise began for 85 minutes, the treatment was stopped for 105 minutes, and the well was pumped out.

The stabilization of dissolved iron concentrations began at the 80th minute, which is close to the beginning of the secondary temperature rise.

After treatment, the flow rate of the well is 7.2 m ³ / h with a decrease in the level of 8.0 m,

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the specific flow rate of the well is determined to be 0.9 m ³ / h.

Example 3. A borehole with a depth of 82 m and a casing diameter of 8 ^{G /} captures water-saturated fractured sandstones. It is equipped with a filter length of 8.5 m in the form of a perforated pipe with a diameter of 8 with a borehole of about 20%. For a period of operation equal to 16 years, the flow rate at a fall of 3 m decreased from 1.2 to 0.24 m ³ / h. ten

600 l of hydrochloric acid of 25% concentration is pumped into the well filter and a three electrode heater 1.6 m long is installed with a packer separating the filter from the well bore. The heater is connected through a three-phase diode rectifier through a 5-cycle rectifier. Maximum power take-off is 25 kVA.

After turning on the heater, measure the temperature of the solution using a sensor connected by a cable with a Sh69000 type logometer.

The measurement results are presented in the table.

The end time of thermoreagent treatment by the secondary temperature rise, which '5 is fixed at the 36th minute. The well treatment is completed at the 48th minute.

After treatment, the flow rate of the well is 1.65 m ³ / h at a decrease of 3 m, the specific flow rate of the well is determined to be 0.55 m ³ / h. de

Example 4. A well with a depth of 25 m and a casing diameter of 8 "caps water-saturated fractured sandstones. It

equipped with a 10 m long filter in the form of an 8 ”diameter perforated pipe with a duty cycle of 20%. Over a period of 16 years, the well production rate decreased from 1.17 to 0.33 m ³ / h with a decrease of 3 m.

600 liters of hydrochloric acid are pumped into the well filter! 25% concentration and install a three-electrode heater with a length of 1.6 m with a packer separating the filter from the wellbore. The heater is connected to a three-phase network through a diode loluperiodic rectifier. Maximum power take-off is 25 kVA.

After turning on the heater, the temperature of the solution is measured using a sensor connected by a cable to a P169000 type logometer.

The measurement results are shown in Table. four.

The end time of thermoreagent treatment is determined by the secondary temperature rise, which is fixed at the 56th minute. The well treatment is completed at the 60th minute.

After treatment, the flow rate of the well is 1.74 m ³ / h at a decrease of 3 m, the specific flow rate of the well is determined to be 0.58 m ³ / h.

The application of the proposed method in the thermoagent treatment of wells allows one to sufficiently reliably control the almost complete dissolution of clogging formations while maintaining the integrity of the structural elements of the filter in hot, aggressive solutions.

Table 1

Time

processing,

MIN 0 ten 20 thirty 40 50 60 70 80 90 100 110 120 Temperature the solution ° С 12 39 47 64.5 71.5 76.5 81 84 85.5 86 76 73 76 Concentration solution gland, g / l 0.8 1,3 2.5 5.4 7.0 7.05 7,6 7.4 8.15 8.1 8.0 8.2 8.2

5 1177455 ₆

table 2

Time processing, min 0 ten 20 thirty 40 50 60 · 70 80 85 90 95 100 105 Temperature the solution ° С 14 32 44 52 62.5 70 74 79 65 67 67.5 68.5 69 69.5 Concentration dissolved gland, g / l 1.2 2.0 3.1 4.3 5.15 5.6 5.85 5.9 6.1 6.05 6.0 6.1 6.15 6.1

Table 3

Time

processing,

min 0 4 8 12 16 20 14 28 32 36 40 41

Temperature _;

solution,,

° С 8 62 83 81 68 63 62 60,5 58 60,0 61,5 62

Table 4

Time

processing,

min 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60

Temperature

the solution

° С 8 20 35 48 61 78 84 91

83.5 78 73 66 64. 60 61.5 63

,

Claims (2)

METHOD OF CONTROL OF THE PROCESS OF DISSOLUTION OF COLMATING FORMATIONS OF WELLS when thermoreagently processing by measuring the parameter of the solution and stopping the process, characterized in that, in order to increase the productivity of the well by improving the accuracy of control, measure the temperature of the solution and stop the process at the moment the secondary temperature of the solution begins to rise. .and m m SP SL 1177455 2