RU2583803C1 - Formation hydraulic fracturing method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used for intensification of well operation. Method of hydraulic fracturing, including test forcing of fracturing fluid and pile of fracturing fluid with proppant, correcting fracturing project and performing of main fracturing process, while pumping components in fracturing fluid is a mixture of 10-27 % solution of hydrochloric acid, methylene-phosphoric acid and water in concentration of 1-2 l per 1 m³ of fracturing fluid, at ratio of hydrochloric acid solution, methylene-phosphoric acid and water (15-25):(55-65):(15-25) vol%, respectively.

EFFECT: increased efficiency of hydraulic fracturing.

1 cl, 3 ex

Description

The invention relates to the oil industry and may find application in stimulating well operation.

A known method of hydraulic fracturing (Fracturing), which pre-analyze the technical water, test the gel for water solubility and structure formation, with a satisfactory result, dissolve the gel in water and again test for structure formation, with satisfactory results, a clay stabilizer is added to the gel solution in water, demulsifier and degradation regulator, the resulting solution is pumped into the well and in the process of injection, a destructor and a crosslinker are introduced into the solution, thus the fracturing fluid, pumping replace the volume of the well to a fracturing fluid, stopping downloading and produce pressure decay record resuming download fracturing fluid with a working flow in hydraulic fracturing is pumped "cushion" the fracturing fluid in a volume of from 3 to 6 m ^3, and then operate download test packs fracturing fluid with proppant mass to 1 in a concentration of from 30 to 200 kg / m ^3, it is adjusted to the perforated interval, note the initial surface pressure is then recorded and the character of its change during passage na ki through the perforations and its movement through the fracture, the fracturing fluid is forced pack interval without proppant in the amount of 1.5-1.8 m ³ prodavku produce fracturing fluids in a volume equal to the volume of the column tubing, packer zone to the roof at the perforations and another 2-4 ^m3 prodavku stop and produce pressure decay record produce the recording and processing of intensity reduction of wellhead pressure, the obtained data was treated to give data about the performance of the fracturing fluid, the pressure value of the gradient voltage pressure in the reservoir, time and pressure of fracture closure, pore pressure in the reservoir, hydraulic pressure losses in the perforation interval and the bottom of the reservoir, on the basis of the data obtained, the design data of the fracturing process are adapted to the data obtained for processing the test injection, the corrected data is used to re-calculate the three-dimensional models of hydraulic fracturing and conducting an updated version of hydraulic fracturing, change the initial plan for carrying out the main hydraulic fracturing process by replacing the original The initial data of mining and geological coefficients for obtained by the program after the test injection process, carry out the modified main hydraulic fracturing process, when conducting the modified basic hydraulic fracturing process, based on the calculations made, the required volume of process water is set up and the gel is prepared with testing, and the hydraulic fracturing process is satisfactory carried out in accordance with the amended plan, where the volume of the final sale is defined as the sum of the volume columns of tubing and sub-packer zone to the roof of the perforation interval, when detecting an increase in wellhead pressure during the injection of a test pack of fracturing fluid with proppant by 1 to 2.5 MPa, increase the volume of injected proppant of small and medium fractions 20/40, 16/30 and 16/20 mesh at minimum concentrations from 30 to 120 kg / m ³ to 800-1000 kg per stage, the effectiveness of this measure is estimated by the wellhead pressure decrease as this pack of proppant passes through the perforation zone and when the pressure decreases by 1 or more MPa doing The conclusion is that the hydraulic connection with the formation is improved and the hydraulic fracturing process should be performed according to the planned parameters according to the amended plan, in the absence of signs of restoration of communication with the formation, the proppant feed concentration in the following stages is reduced, being limited to the maximum values of 350-400 kg / m ³ , proppant injection -gel mixture is performed in two portions, in the first portion, the dosage of the destructor is carried out according to the concentration that provides the complete process of gel decomposition, and the crack closure time is not less than 12 hours, in the second portion, the dosage of the destructor is carried out according to the concentration that ensures the process of complete decomposition of the gel, and the crack closure time is not more than 4 hours, after pumping the proppant-gel mixture, the pump units stop and record the pressure drop to obtain information about the quality of the fracturing process , about the pressure drop intensity, the presence of a residual connection with the formation, the absence of a reselling effect, after which the wellhead is closed, the well is left to wait for the pressure drop, at the end of the necessary time for gel destruction, the residual wellhead pressure is vented to atmospheric pressure, the overpressure is vented after 4 hours, at a pressure of more than 4 MPa, the venting is performed at a flow rate of not more than 30 l / min to atmospheric pressure, and at a pressure of less than 4 MPa on the wellhead pressure gauge, the bleed is done by the full opening of the wellhead valve, the wellhead is depressurized, the packer is broken and the underground equipment is lifted (RF Patent No. 2453694, publ. 06/20/2012).

The closest to the invention in technical essence is the hydraulic fracturing method, according to which technical water is preliminarily analyzed, the gel former is tested for solubility in water and structure formation, with a satisfactory result, the gel former is dissolved in water and again tested for structural formation, with satisfactory results, the gel former in water is added clay stabilizer, demulsifier and degradation regulator, pump the resulting solution into the well and in the process the creator is injected with a destructor and a crosslinker, thereby forming a fracturing fluid, by pumping, replace the well volume with a fracturing fluid, stopping the injection and recording the pressure drop, resume injecting the fracturing fluid with a working flow for hydraulic fracturing, pumping a “pillow” of fracturing fluid in the volume from 3 to 6 m ³ , then a test pack of fracturing fluid is injected with a proppant weighing up to 1 t with a concentration of 30 to 200 kg / m ³ , bring it to the perforation interval, the initial wellhead pressure is noted, and then character If it changes during the passage of the pack through the interval of perforation and its movement along the crack, the pack is pressed with rupture fluid without proppant in a volume of 1.5-1.8 m ³ , the rupture fluid is squeezed in a volume equal to the volume of the tubing string, sub-packer zones to the roof in the perforation interval and another 2-4 m ³ , stop selling and record the pressure drop, record and process the rate of wellhead pressure decrease, process the received data, obtain data on the fluid’s performance fracture, pressure value, stress gradient in the formation, time and pressure to close the crack, pore pressure in the reservoir, hydraulic pressure losses in the interval of perforation and bottom-hole part of the formation, on the basis of the data obtained, the design data of the fracturing process are adapted to the received test injection processing data, adjusted the data is used to re-calculate the three-dimensional model of hydraulic fracturing and conduct an updated version of hydraulic fracturing, change the initial plan of the main fracturing process by replacing the initial data of geological coefficients with the ones obtained by the program after the test injection process, carry out the modified hydraulic fracturing process, when carrying out the modified hydraulic fracturing process based on the calculations performed, the required volume of process water is set up and the gel is prepared with testing, if satisfactory the test results, the fracturing process is carried out in accordance with the amended plan, where the volume of ary prodavki defined as the sum of the column volume of tubing and packer zone to roofing perforation interval, injecting proppant-gel mixture is performed in two portions, a first portion of the set concentration of proppant to 300 kg / m ^3, dosage destructor performed according concentration providing complete process decomposition and gel fracture closure time of at least 12 h, a second portion mounted proppant concentration in excess of 300 kg / m ^3, is performed according destructor dosage concentration, providing the process of complete decomposition of the gel and the time it takes to close the crack for no more than 4 hours, at the end of the proppant-gel mixture completion, the pumping units stop and record the pressure drop to obtain information about the quality of the fracturing process, the pressure drop intensity, the presence of residual connection with the formation, and the absence the effect of reselling, after which the wellhead is closed, the equipment is dismantled and the well is left to wait for a drop in pressure, at the end of the necessary time for the destruction of the gel, the production t, the residual wellhead pressure is vented to atmospheric pressure, the overpressure is vented after 4 hours, at a pressure of more than 4 MPa on the wellhead pressure gauge, the pressure is not more than 30 l / min to atmospheric pressure, and at a pressure of less than 4 MPa on the wellhead pressure gauge the full opening of the wellhead valve, the wellhead is depressurized, the packer is broken and the underground equipment is lifted (RF Patent No. 2453695, publ. 06/20/2012 - prototype).

A common disadvantage of the known methods is the low efficiency of hydraulic fracturing.

The invention solves the problem of increasing the efficiency of hydraulic fracturing.

The problem is solved in that in the method of hydraulic fracturing, comprising a test injection of fracturing fluid and a pack of fracturing fluid with proppant, correcting the fracture design and conducting the main fracturing process, according to the invention, a mixture of 10-27% hydrochloric acid solution is introduced into the fracturing fluid when injecting components , methylene-phosphoric acid and water in a concentration of 1-2 l per 1 m ^{3 of the} fracturing liquid, with a ratio of a solution of hydrochloric acid, methylene-phosphoric acid and water (15-25) :( 55-65) :( 15-25) about .%, respectively.

SUMMARY OF THE INVENTION

When developing an oil field, the production rate and injectivity of wells are inevitably reduced. One of the most effective ways to increase well productivity is hydraulic fracturing. However, even after hydraulic fracturing, the decline in well productivity continues. One of the reasons for the decline in well productivity is the salts formed during operation, which clog the fracture. The invention solves the problem of increasing the efficiency of hydraulic fracturing by slowing down the process of scaling in the hydraulic fracture. The problem is solved as follows.

In hydraulic fracturing, a fracturing fluid is injected with it added mainly at the stage of adding a crosslinker of a scale inhibitor, which is used as a mixture of 10-27% hydrochloric acid solution (by volume), methylene phosphoric acid and water at a ratio of 20:60: 20% (by volume), respectively. The mixture is injected at a concentration of 1-2 l per 1 m ^{3 of} fracturing fluid.

All these solutions slow down the process of salt formation and cracking, which ultimately increases the duration of the treatment effect.

Case Studies

Example 1. Perform hydraulic fracturing in an oil well. Perform a test download. The initial injectivity of the fracturing object Q-220 m ³ / day, initial pressure Pnach = 19 MPa, final pressure Pkon = 20 MPa. The quality of communication with the formation is determined by injecting 5 m ^{3 of} technical fluid with a density of 1.18 g / cm ³ without preliminary saturation of the bottomhole zone.

During hydraulic fracturing, technical water samples are taken and analyzed for the content of mechanical impurities, the content of free hydrogen ions and temperature, test preparation of the fracturing fluid is carried out, a test for dissolution and crosslinking is performed. The results are satisfactory. A gel is prepared in a volume of 25 m ³ based on a WG 46 Econotec gelling agent based on guar gum (manufactured by Economy Polymers & Chemicals). Rheology - temperature 27 ° C, viscosity 21 cP, crosslinking time 4 s. A demulsifier, a degradation activator and a clay stabilizer are added to the gel, the mixture is brought to a homogeneous state with stirring, and the pressure pumps are started and heated.

A test injection is performed with recording the pressure drop and processing the data on pressure drop in the volume of 25 m ^{3 of the} fracturing liquid with the addition of 1000 kg of proppant fraction 20/40 and 25 l of a mixture of 20% hydrochloric acid, methylene phosphoric acid and water a ratio of 20: 60: 20% (by volume), respectively, i.e. at a concentration of 1 liter per 1 m ^{3 of} rupture fluid. The test pack went through the perforation interval with increasing pressure from 19 MPa to 20 MPa. The data obtained are processed, data are obtained on the performance of the fracturing fluid, the value of the net pressure, the stress gradient in the formation, the time and pressure to close the fracture, the pore pressure in the reservoir, hydraulic pressure losses in the perforation interval and the bottom of the formation. Based on the data obtained, the design data of the fracturing process are adapted to the received test injection processing data.

The main hydraulic fracturing process is carried out.

Corrected data is used to re-calculate the three-dimensional fracturing model and refine the fracturing plan. Based on the calculations made, a set of the required volume of the process fluid is prepared and a fracture fluid is prepared with testing. The test results are satisfactory. The process of hydraulic fracturing is carried out in accordance with a detailed updated plan, the preparation of the fracturing fluid is carried out with the loading of a gel-forming agent 3.0 kg / m ³ and with a proppant concentration in stages: 120 kg / m ³ , 200 kg / m ³ , 250 kg / m ³ , 300 kg / m ³ , 350 kg / m ³ , 400 kg / m ³ , 500 kg / m ³ , 600 kg / m ³ , 700 kg / m ³ , 800 kg / m ³ to improve the hydrodynamic connection of the formation with a fracture.

In the process of the main process, 80 m ^{3 of the} fracture fluid is added in a proportion of 2 l per 1 m ^{3 of the} fracture fluid, i.e. in a volume of 0.16 m ^{3 a} mixture of a 27% solution of hydrochloric acid, methylene phosphoric acid and water at a ratio of 15: 60: 25% (by volume), respectively.

The final proppant concentration is 800 kg / m ³ , which corresponds to 114% of the final proppant concentration during the first hydraulic fracturing.

The load of the gelling agent is 3.0 kg / m ³ .

The pressure at the wellhead is the initial 20 MPa, the final 23 MPA, where the volume of the final push is defined as the sum of the volume of the tubing string and sub-packer zone to the roof of the perforation interval minus the volume of the estimated undersupply. Operating flow rate for the main process 2.5 m ³ / min At the end of the proppant-gel mixture sale, the pumping units are stopped and the pressure drop recorded, after which the wellhead is closed, the equipment is dismantled and the well is left to wait for the pressure drop. At the end of the necessary time for the destruction of the gel, the residual wellhead pressure is vented to atmospheric pressure. The start of overpressure release is carried out after 12 hours. The wellhead is depressurized, the packer equipment is stalled and lifted.

According to the results of processing the results of recording the wellhead pressures of the performed process, the following data were obtained: fixed crack length (one wing) - 102.85 m; the height of the crack created - 13.77 m; fixed - 8.53 m. The width of the fracture after relieving pressure in the reservoir is 3.0 mm, the maximum width of the fracture at the perforation intervals is 21.06 mm; crack conductivity 1784.4 mD / m. The injected proppant has a mass of 15,000 kg (20/40 - 2,000 kg, 12/18 - 13,000 kg), which is 36% higher than in the previous treatment.

Example 2

Perform as example 1. During hydraulic fracturing, when pumping the components into the fracturing fluid at the stage of adding a crosslinker, 70 m ³ are added in a proportion of 1 liter per 1 m ^{3 of} fracturing fluid, i.e. in a volume of 0.07 m ^{3, a} mixture of a 27% solution of hydrochloric acid, methylene phosphoric acid and water at a concentration of 1 l per 1 m ^{3 of} fracturing liquid, with a ratio of a solution of hydrochloric acid, methylene phosphoric acid and water 15:60:25 % (by volume), respectively.

Example 3

They are carried out as example 1. In the main process, 1.5 l per 1 m ^{3 of the} fracturing fluid is added to the fracture fluid in a volume of 70 m ³ , i.e. in a volume of 0.105 m ^{3 a} mixture of a 10% solution of hydrochloric acid, methylene phosphoric acid and water at a ratio of 25: 60: 15% (by volume), respectively.

Example 4. Perform as example 1. As a gelling agent use GPG-3 - a polysaccharide according to TU 2499-072-17197708-2003 (manufacturer ZAO Petrohim).

During test injection into the fracture liquid in a volume of 70 m ³ , a mixture of a 10% solution of hydrochloric acid, methylene phosphoric acid and water is added at a ratio of 25: 55: 20% (by volume), respectively, at a concentration of 1 liter per 1 m ^{3 of} liquid gap, i.e. in the amount of 0.07 m ³ .

In the process of the main process, 80 m ^{3 of the} fracture fluid is added in a proportion of 2 l per 1 m ^{3 of the} fracture fluid, i.e. in a volume of 0.160 m ^{3 a} mixture of a 20% solution of hydrochloric acid, methylene phosphoric acid and water at a ratio of 20: 65: 15% (by volume), respectively.

In the proposed hydraulic fracturing, a fracturing fluid is used with the addition of a scale inhibitor at a concentration of 1-2 l / m ³ . The use of a salt formation inhibitor is to increase the duration of the effect of hydraulic fracturing. As a result of well operation, it was found that the well flow rate after hydraulic fracturing is maintained for 3 years, while in the prototype well, the flow rate in 1 year is reduced to almost zero due to the formation of a fracture fracture by scaling.

Thus, the proposed method allows to increase the efficiency of hydraulic fracturing.

Claims (1)

The method of hydraulic fracturing, including a test injection of fracturing fluid and a pack of fracturing fluid with proppant, adjusting the fracturing design and conducting the main fracturing process, characterized in that when injecting the components, a mixture of 10-27% solution of hydrochloric acid, methylene phosphoric is introduced acid and water in a concentration of 1-2 l per 1 m ^{3 of} fracturing liquid, with a ratio of hydrochloric acid, methylene phosphoric acid and water (15-25): (55-65) :( 15-25) vol.%, respectively.