CN104101559B - Measure the device and method of supercritical carbon dioxide fracturing fluid rheological characteristic - Google Patents

Abstract

The invention belongs to unconventionaloil pool production technique field, in particular it relates to a kind of device and method measuring supercritical carbon dioxide fracturing fluid rheological characteristic.Measurement apparatus includes: supercritical carbon dioxide pressure charging system, tackifier inject hybrid system and the supercritical carbon dioxide fracturing fluid circulatory system；The critical carbon dioxide fracturing fluid circulatory system provides the closed circuit of Guan Bi under HTHP for supercritical carbon dioxide fracturing fluid, supercritical carbon dioxide pressure charging system for carbon dioxide provide required for experimental pressure, tackifier inject hybrid system tackifier are pumped in HTHP supercritical carbon dioxide pipeline.The present invention is capable of the measurement of bigger pressure and temperature wide-ultra critical carbon dioxide fracturing fluid rheological parameter, the constitutive relation of supercritical carbon dioxide fracturing fluid rheological behavior under available different temperatures, pressure condition；Device is simple to operate, and method is easy to implement, and feasibility is high；Measuring method science, it is possible to realize the parameter measurement of degree of precision.

Description

Measure the device and method of supercritical carbon dioxide fracturing fluid rheological characteristic

Technical field

The invention belongs to unconventionaloil pool production technique field, in particular it relates to a kind of measurement surpasses The device and method of critical carbon dioxide fracturing fluid rheological characteristic.

Background technology

Unconventional gas resource includes coal bed gas, shale gas, compact sandstone gas and Water Soluble Gas Deng, current unconventional petroleum resources plays key player in global energy structure.Non- The reservoir properties of conventional gas and oil resource is the most poor, has low-porosity, low-permeability, low hole The physical property characteristics such as larynx radius, the more conventional oil-gas reservoir of flow resistance of oil gas is big many, and along with The intensification that reservoir buries, reservoir properties is deteriorated so that conventional production technique does not possess business exploitation Being worth, determining unconventional petroleum resources needs to take fracture technology to improve well yield. Hydraulic fracturing technology is applied to the exploitation of the unconventionaloil pool such as shale gas and tight gas Tibetan and can produce The series of problems such as water-sensitive, reservoir pollution, and water resources shortage is also restriction fracturing Key factor.

Supercritical carbon dioxide has the low viscosity of gas and high diffusivity coefficient and the height of liquid concurrently Density and good dissolubility.Supercritical carbon dioxide pressure break is a kind of novel unconventional natural Gas Reservoir renovation technique, compared with conventional hydraulic pressure break, supercritical carbon dioxide fracturing fluid has Have low leak-off, height return row, little to reservoir pollution, prevent clay mineral hydration swelling etc. many excellent Point.Therefore, supercritical carbon dioxide pressure break can improve unconventionaloil pool reservoir flow conductivity, Realize one of effective means of business high-efficiency mining.Supercritical carbon dioxide fracturing fluid is tackifier The compounding substances being dissolved in supercritical carbon dioxide.At present, by temperature, pressure influence, surpass and face The Rheological Regularity of boundary's carbon dioxide pressure break liquid is considerably complicated, rarely has test data, for rheological characteristic The explanation of mechanism also neither one system, thus become one of supercritical fluid research field Difficult point.

Summary of the invention

For overcoming the defect existing for prior art, the present invention provides a kind of and measures overcritical dioxy Change carbon pressure and split the device and method of liquid flow sex change, for quickly measuring under different Temperature-pressure Conditions The rheological parameter of supercritical carbon dioxide fracturing fluid, and then network analysis supercritical carbon dioxide pressure Split the rheological characteristic of liquid, provide experiment base for supercritical carbon dioxide FRACTURING DESIGN and theoretical research Plinth.

For solving above-mentioned technical problem, the technical solution adopted in the present invention is as follows:

Measure the device of supercritical carbon dioxide fracturing fluid rheological characteristic, including: overcritical titanium dioxide Carbon pressure charging system, tackifier inject hybrid system and supercritical carbon dioxide fracturing fluid cyclic system System；The supercritical carbon dioxide fracturing fluid circulatory system provides height for supercritical carbon dioxide fracturing fluid The closed circuit of Guan Bi under temperature high pressure, supercritical carbon dioxide pressure charging system provides for carbon dioxide Required experimental pressure, tackifier are pumped into HTHP and surpass by tackifier injection hybrid system In critical carbon dioxide pipeline.

The method measuring supercritical carbon dioxide fracturing fluid rheological characteristic, uses above-mentioned experimental provision, When carrying out supercritical carbon dioxide fracturing fluid rheology tests, adjust carbon dioxide air source and enter Mouth screws valve, tackifier entrance screws valve, the emptying of supercritical carbon dioxide fracturing fluid screws at valve In closed mode, vavuum pump is utilized to get rid of the air in experiment pipeline；Open carbon dioxide air source Entrance screws valve, circulating pump, makes carbon dioxide enter supercritical carbon dioxide fracturing fluid cyclic system System, regulates gas boosting pump, oil bath heater, the temperature of experimental system, pressure is adjusted to The temperature, pressure that experiment sets；Open tackifier entrance and screw valve, tackifier measuring pump, plunger Tackifier in tackifier storage tank are pumped into the supercritical carbon dioxide fracturing fluid circulatory system by pump, Fluid (tackifier, carbon dioxide) flows under circulating pump effect, and tackifier fill in clean mixed device Divide and be dissolved in supercritical carbon dioxide；After parameter stability, carry out supercritical carbon dioxide pressure Splitting the mensuration of liquid flow sex change, differential pressure pick-up record fluid is measuring the differential pressure of flow of line sections, Mass flowmenter display supercritical carbon dioxide fracturing fluid mass flow, is calculated setting temperature Supercritical carbon dioxide fracturing fluid Rheology Constitutive Equation under degree, pressure.

Relative to prior art, beneficial effects of the present invention is as follows:

(1), it is capable of bigger pressure and temperature wide-ultra critical carbon dioxide pressure break liquid flow The measurement of variable element, supercritical carbon dioxide fracturing fluid under available different temperatures, pressure condition The constitutive relation of rheological behavior；

(2), device simple to operate, method is easy to implement, and feasibility is high；

(3), measuring method science, it is possible to realize the parameter measurement of degree of precision.

Accompanying drawing explanation

Fig. 1 is the device schematic diagram for measuring supercritical carbon dioxide fracturing fluid rheological characteristic；

In figure: 11, carbon dioxide air source；12, gas buffer tank；13, gas boosting pump； 14, carbon dioxide gas source inlet screws valve；21, tackifier storage tank；22, tackifier measuring pump； 23, plunger displacement pump；24, tackifier entrance screws valve；31, intermediate receptacle；311, oil bath adds Hot device；312, thermometer in intermediate receptacle；313, intermediate receptacle inner gauge；32, circulation Pump；33, device is only mixed；34, line sections is measured；341, the import of carbon dioxide pressure break liquid is measured Pressure gauge；342, thermometer is measured in the import of carbon dioxide pressure break liquid；343, line sections is measured poor Pressure sensor；344, thermometer is measured in the outlet of carbon dioxide pressure break liquid；345, pressurized carbon dioxide Split liquid outlet and measure pressure gauge；35, mass flowmenter；36, vavuum pump；37, overcritical two The emptying of carbonoxide fracturing fluid screws valve.

Detailed description of the invention

As it is shown in figure 1, measure the device of supercritical carbon dioxide fracturing fluid rheological characteristic, including: Supercritical carbon dioxide pressure charging system, tackifier inject hybrid system and supercritical carbon dioxide pressure Split fluid circulation；The supercritical carbon dioxide fracturing fluid circulatory system is supercritical carbon dioxide pressure Splitting liquid and provide the closed circuit of Guan Bi under HTHP, supercritical carbon dioxide pressure charging system is two Experimental pressure required for carbonoxide offer, tackifier inject hybrid system and are pumped into by tackifier In HTHP supercritical carbon dioxide pipeline.

Supercritical carbon dioxide pressure charging system, including: carbon dioxide air source 11, gas buffer Tank 12, gas boosting pump 13, carbon dioxide gas source inlet screw valve 14, carbon dioxide air source 11, gas buffer tank 12, gas boosting pump 13, carbon dioxide gas source inlet screw valve 14 and depend on Secondary connected by pipeline；Carbon dioxide air source 11 provides the carbon dioxide needed for experiment, gas Surge tank 12 is for storing the carbon dioxide of high pressure, the titanium dioxide in gas buffer tank 12 Carbon flows to gas boosting pump 13, and gas boosting pump 13 is that carbon dioxide supercharging is with satisfied experiment pressure Power requirement, carbon dioxide screws valve 14 by carbon dioxide gas source inlet and enters overcritical Carbon dioxide pressure break fluid circulation.

Tackifier inject hybrid system, including: tackifier storage tank 21, tackifier measuring pump 22, Plunger displacement pump 23, tackifier entrance screw valve 24；Tackifier storage tank 21, tackifier measuring pump 22, Plunger displacement pump 23, tackifier entrance screw valve 24 and pass sequentially through pipeline connection；Tackifier storage tank 21 Built with being soluble in the solvent of supercritical carbon dioxide, for improving the viscous of supercritical carbon dioxide Degree, tackifier measuring pump 22 to add thickening dosage carry out accurate measurement, plunger displacement pump 23 via Tackifier entrance screws valve 24 and tackifier pumps into supercritical carbon dioxide fracturing fluid cyclic system System.

The supercritical carbon dioxide fracturing fluid circulatory system, including: intermediate receptacle 31, mixes device only 33, line sections 34, mass flowmenter 35 are measured；Intermediate receptacle 31 port of export and clean mixed device 33 entrance points are connected by pipeline, clean mixed device 33 port of export and mass flowmenter 35 entrance point It is connected by measuring line sections 34, mass flowmenter 35 port of export and intermediate receptacle 31 import Hold and be connected, forming the closed circuit of a Guan Bi.

Intermediate receptacle 31 is provided with circulating pump 32, circulating pump with the connection pipeline of clean mixed device 33 32 provide the power needed for closed circulation for supercritical carbon dioxide fracturing fluid, and circulating pump 32 makes Fluid is flowed to clean mixed device 33 direction by intermediate receptacle 31；Tackifier entrance screws valve 24 and leads to Cross pipeline and access clean mixed pipeline between device 33 and circulating pump 32；Intermediate receptacle 31 faces super Boundary's carbon dioxide pressure break liquid carries out buffer storage, and tackifier are sufficiently mixed dissolving by clean mixed device 33 In supercritical carbon dioxide, form supercritical carbon dioxide fracturing fluid fluid.

Intermediate receptacle 31 is placed in oil bath heater 311, and intermediate receptacle 31 is provided with intermediate receptacle Interior thermometer 312, intermediate receptacle inner gauge 313；Oil bath heater 311 is to overcritical two Carbonoxide fracturing fluid heats to reach experimental temperature requirement, and in intermediate receptacle, thermometer 312 is measured Temperature in intermediate receptacle, intermediate receptacle inner gauge 313 measures the pressure in intermediate receptacle.

Measure on pipeline 34, by only mixing device 33 to mass flowmenter 35 direction, be sequentially provided with Pressure gauge 341 is measured in carbon dioxide pressure break liquid import, temperature is measured in carbon dioxide pressure break liquid import Temperature is measured in meter 342, measurement line sections differential pressure pick-up 343, the outlet of carbon dioxide pressure break liquid Pressure gauge 345 is measured in the outlet of meter 344, carbon dioxide pressure break liquid；Carbon dioxide pressure break liquid import Measure pressure gauge 341, the outlet of carbon dioxide pressure break liquid is measured pressure gauge 345 and is measured present position Pipeline in pressure；Thermometer 342, carbon dioxide pressure break are measured in carbon dioxide pressure break liquid import Temperature in the pipeline of liquid outlet measurement thermometer 344 real-time monitored present position；Measure line sections Differential pressure pick-up 343 is used for measuring supercritical carbon dioxide fracturing fluid and flows through measurement line sections 34 The pressure differential produced；Measuring section line sections 24 is internal diameter 6mm, wall thickness 2mm, length 7.5m The copper pipeline of external application heat-insulation layer.

The pipeline that mass flowmenter 35 is connected with intermediate receptacle 31 is provided with vavuum pump 36, Carbon dioxide gas source inlet screws valve 14 by pipeline cut-in quality flowmeter 35 and intermediate receptacle In pipeline between 31；Mass flowmenter 35 is for measuring supercritical carbon dioxide fracturing fluid Mass flow, vavuum pump 36 is for getting rid of the air in experiment pipeline.Supercritical carbon dioxide Fracturing fluid emptying screws valve 38 and accesses vavuum pump 36 and intermediate receptacle 31 connecting tube by pipeline Lu Shang, it is super for being vented in experiment pipeline that the emptying of supercritical carbon dioxide fracturing fluid screws valve 38 Critical carbon dioxide fracturing fluid.

In close loop, all parts and the most pressure 60MPa of pipeline, temperature upper limit is 500K, can realize supercritical carbon dioxide supercritical carbon dioxide fracturing fluid at high temperature under high pressure The experiment of rheological characteristic is measured.

The method measuring supercritical carbon dioxide fracturing fluid rheological characteristic, utilizes said apparatus, step As follows:

(1) supercritical carbon dioxide circulation, is set up

Adjust that carbon dioxide gas source inlet screws valve 14, tackifier entrance screws valve 24, super face Boundary's carbon dioxide pressure break liquid emptying screws valve 38 and is closed, and utilizes vavuum pump 36 to get rid of Air in experiment pipeline；Open carbon dioxide gas source inlet and screw valve 14, circulating pump 32, Carbon dioxide is made to be flowed out by carbon dioxide air source 11, regulation gas boosting pump 13, oil bath heating Device 311, is adjusted to, by the temperature of experimental system, pressure, the temperature, pressure that experiment sets.

(2), tackifier are added

Open tackifier entrance and screw valve 24, tackifier measuring pump 22, plunger displacement pump 23, will increase Tackifier in stick storage tank 21 pump into the supercritical carbon dioxide fracturing fluid circulatory system, fluid (tackifier, carbon dioxide) flows under circulating pump 32 acts on, and tackifier are in clean mixed device 33 It is completely dissolved in supercritical carbon dioxide；After parameter stability, carry out supercritical carbon dioxide The measurement of fracturing fluid rheological characteristic.

(3), supercritical carbon dioxide fracturing fluid mean temperature in line sections is calculated

Read supercritical carbon dioxide fracturing fluid import and measure temperature T of thermometer 342₁, outlet Measure temperature T of thermometer 344₂, calculate supercritical carbon dioxide fracturing fluid in line sections Mean temperature:

$T=\frac{T_1+T_2}{2}---\left(1\right)$

In formula, T is supercritical carbon dioxide mean temperature in measuring line sections pipe, K； T₁The temperature of line sections Guan Nei import department, K is being measured for supercritical carbon dioxide fracturing fluid；T₂ The temperature at line sections pipe inner outlet, K is being measured for supercritical carbon dioxide fracturing fluid.

(4), supercritical carbon dioxide fracturing fluid average pressure in line sections is calculated

Read supercritical carbon dioxide fracturing fluid import and measure the pressure P of pressure gauge 341₁, go out The pressure P of mouth measurement pressure gauge 345₂, calculate supercritical carbon dioxide fracturing fluid in line sections Interior average pressure:

$P=\frac{P_1+P_2}{2}---\left(2\right)$

In formula, P is supercritical carbon dioxide average pressure in measuring line sections pipe, MPa； P₁The pressure of line sections Guan Nei import department, MPa is being measured for supercritical carbon dioxide fracturing fluid； P₂The pressure at line sections pipe inner outlet, MPa is being measured for supercritical carbon dioxide fracturing fluid.

(5) supercritical carbon dioxide fracturing fluid flow velocity in measuring line sections, is calculated

Supercritical carbon dioxide fracturing fluid mass flow Q of reading quality flowmeter 35, calculates Supercritical carbon dioxide fracturing fluid flow velocity in measuring line sections 34:

Z³-(1-B)Z²+(A-3B²-2B)Z-(AB-B²-B³)=0 (3)

$A=0.45724\left(\frac{{\[1+(0.37464+1.5226w-0.26992w^2)(1-T_r^{0.5})\]}^2{p}_r}{T_r^2}\right)---\left(4\right)$

$B=0.077796\left(\frac{p_r}{T_r}\right)---\left(5\right)$

${\mathrm{\ρ}}_{{\mathrm{CO}}_2}=\frac{{\mathrm{PM}}_g}{ZRT}---\left(6\right)$

$\mathrm{\ρ}={\mathrm{\ρ}}_{{\mathrm{CO}}_2}{x}_{{\mathrm{CO}}_2}+{\mathrm{\ρ}}_t{x}_t---\left(7\right)$

$u=\frac{4Q}{{\mathrm{\ρ\πD}}^2}---\left(8\right)$

In formula, Z is compressibility factor, dimensionless；A, B are intermediate variable, expression formula such as formula (4), shown in (5)；p_rFor reduced pressure, dimensionless；T_rFor reduced temperature, dimensionless； W is the eccentric factor of carbon dioxide, dimensionless；ρ_CO2For the density of carbon dioxide, kg/m³； x_CO2For carbon dioxide ratio in supercritical carbon dioxide fracturing fluid, dimensionless；ρ_tFor increasing The density of stick, kg/m³；ρ is the density of supercritical carbon dioxide fracturing fluid, kg/m³；x_t For tackifier ratio in supercritical carbon dioxide fracturing fluid, dimensionless；P is absolute pressure, MPa；T is absolute temperature, K；M_gFor the molecular weight of carbon dioxide, kg/m³；R is general Gas constant, 0.008314MPa m³/(kmol·K)；Q is supercritical carbon dioxide fracturing fluid Mass flow, kg/s；D is for measuring line sections 34 diameter, m；U is overcritical titanium dioxide Carbon fracturing fluid flow velocity in pipeline, m/s.

(6), wall shear stress is calculated

Read the pressure differential Δ p measuring line sections differential pressure pick-up 343, be calculated wall and cut Shearing stress:

${\mathrm{\τ}}_w=\frac{D\mathrm{\Δ}p}{4L}---\left(9\right)$

In formula, τ_wFor wall shear stress, Pa；Δ p is for measuring line sections differential pressure pick-up 21 Pressure differential, Pa；L is the length measuring line sections 34, m.

(7) constitutive relation of supercritical carbon dioxide fracturing fluid fluid rheology parameter, it is calculated

At τ_w—Draw logarithmic curve on coordinate, obtain corresponding different τ_wSlope of curve n', And then obtain the constitutive relation of supercritical carbon dioxide fracturing fluid fluid rheology parameter:

$\stackrel{\·}{\mathrm{\γ}}=(\frac{3}{4}+\frac{1}{4n^{\′}})\frac{8u}{D}---\left(10\right)$

$n^{\′}=\frac{dln\left(\frac{D\mathrm{\Δ}p}{4L}\right)}{dln\left(\frac{8u}{D}\right)}---\left(11\right)$

In formula,For supercritical carbon dioxide fracturing fluid fluid shearing rate of deformation, s^-1；N' is different τ_wThe logarithmic coordinates slope of curve.

Change the temperature of experimental system, pressure, supercritical carbon dioxide pressure break liquid flow can be studied Sex change is with temperature, the Changing Pattern of pressure；Thus study the stream of supercritical carbon dioxide fracturing fluid Motivation is managed, and provides experiment basis for supercritical carbon dioxide FRACTURING DESIGN and theoretical research.

Claims (7)

1. measure a device for supercritical carbon dioxide fracturing fluid rheological characteristic, including: overcritical titanium dioxide Carbon pressure charging system, tackifier inject hybrid system and the supercritical carbon dioxide fracturing fluid circulatory system；Its feature It is: the supercritical carbon dioxide fracturing fluid circulatory system provides HTHP for supercritical carbon dioxide fracturing fluid The closed circuit of lower Guan Bi, supercritical carbon dioxide pressure charging system for carbon dioxide provide required for experiment pressure Power, tackifier inject hybrid system and are pumped into by tackifier in HTHP supercritical carbon dioxide pipeline；

Supercritical carbon dioxide pressure charging system, including: carbon dioxide air source, gas buffer tank, gas boosting Pump, carbon dioxide gas source inlet screw valve, carbon dioxide air source, gas buffer tank, gas boosting pump, two Carbonoxide air source inlet screw valve pass sequentially through pipeline be connected；Carbon dioxide is entered by carbon dioxide air source Mouth screws valve and enters the supercritical carbon dioxide fracturing fluid circulatory system；

Tackifier inject hybrid system, including: tackifier storage tank, tackifier measuring pump, plunger displacement pump, thickening Agent entrance screws valve；Tackifier storage tank, tackifier measuring pump, plunger displacement pump, tackifier entrance screw valve successively Connected by pipeline；Tackifier storage tank built with being soluble in the solvent of supercritical carbon dioxide, plunger displacement pump via Tackifier entrance screws valve and tackifier pumps into the supercritical carbon dioxide fracturing fluid circulatory system；

The supercritical carbon dioxide fracturing fluid circulatory system, including: intermediate receptacle, only mix device, measure line sections, Mass flowmenter；The intermediate receptacle port of export is connected by pipeline with clean mixed device entrance point, the clean mixed device port of export and Mass flowmenter entrance point is connected by measuring line sections, the mass flowmenter port of export and intermediate receptacle entrance point Be connected, formed one Guan Bi closed circuit.

The device of measurement supercritical carbon dioxide fracturing fluid rheological characteristic the most according to claim 1, its Being characterised by, intermediate receptacle is provided with circulating pump with the connection pipeline of clean mixed device, and tackifier entrance screws valve and leads to Cross pipeline and access clean mixed pipeline between device and circulating pump；Intermediate receptacle is placed in oil bath heater, middle appearance Device is provided with thermometer, intermediate receptacle inner gauge in intermediate receptacle；Measure on pipeline, by only mixing device to quality Flowmeter direction, is sequentially provided with carbon dioxide pressure break liquid import and measures pressure gauge, carbon dioxide pressure break liquid import Measure thermometer, measure line sections differential pressure pick-up, carbon dioxide pressure break liquid outlet measurement thermometer, dioxy Change the outlet of carbon fracturing fluid and measure pressure gauge；The pipeline that mass flowmenter is connected with intermediate receptacle is provided with vacuum Pump, carbon dioxide gas source inlet screws valve and accesses the pipeline between intermediate receptacle and mass flowmenter by pipeline In.

The device of measurement supercritical carbon dioxide fracturing fluid rheological characteristic the most according to claim 2, its Being characterised by, the emptying of supercritical carbon dioxide fracturing fluid screws valve by pipeline cut-in quality flowmeter with middle On container connecting line.

The device of measurement supercritical carbon dioxide fracturing fluid rheological characteristic the most according to claim 3, its Being characterised by, in supercritical carbon dioxide fracturing fluid circulatory system close loop, all parts and pipeline are equal Pressure 60MPa, temperature upper limit is 500K.

The device of measurement supercritical carbon dioxide fracturing fluid rheological characteristic the most according to claim 4, its Being characterised by, measuring section line sections is internal diameter 6mm, wall thickness 2mm, length 7.5m external application heat-insulation layer Copper pipeline.

6. the method measuring supercritical carbon dioxide fracturing fluid rheological characteristic, uses one of claim 1-5 institute The device measuring supercritical carbon dioxide fracturing fluid rheological characteristic stated, it is characterised in that specifically comprise the following steps that

(1) supercritical carbon dioxide circulation, is set up

Carbon dioxide gas source inlet screws valve, tackifier entrance screws valve, supercritical carbon dioxide pressure break in adjustment Liquid emptying screws valve and is closed, and utilizes vavuum pump to get rid of the air in experiment pipeline；Open titanium dioxide Carbon air source inlet screws valve, circulating pump, makes carbon dioxide be flowed out by carbon dioxide air source, regulates gas boosting Pump, oil bath heater, be adjusted to, by the temperature of experimental system, pressure, the temperature, pressure that experiment sets.

(2), tackifier are added

Open tackifier entrance and screw valve, tackifier measuring pump, plunger displacement pump, by the thickening in tackifier storage tank Agent pumps into the supercritical carbon dioxide fracturing fluid circulatory system, and fluid flows under circulating pump effect, and tackifier exist It is completely dissolved in supercritical carbon dioxide in clean mixed device；After parameter stability, carry out supercritical carbon dioxide The measurement of fracturing fluid rheological characteristic；

(3), supercritical carbon dioxide fracturing fluid mean temperature in line sections is calculated

Read supercritical carbon dioxide fracturing fluid import and measure temperature T of thermometer₁, thermometer is measured in outlet Temperature T₂, calculating supercritical carbon dioxide fracturing fluid mean temperature in line sections:

$T=\frac{T_1+T_2}{2}$

In formula,

T is supercritical carbon dioxide mean temperature in measuring line sections pipe, K；

T₁The temperature of line sections Guan Nei import department, K is being measured for supercritical carbon dioxide fracturing fluid；

T₂The temperature at line sections pipe inner outlet, K is being measured for supercritical carbon dioxide fracturing fluid；

(4), supercritical carbon dioxide fracturing fluid average pressure in line sections is calculated

Read supercritical carbon dioxide fracturing fluid import and measure manometric pressure P₁, pressure gauge is measured in outlet Pressure P₂, calculating supercritical carbon dioxide fracturing fluid average pressure in line sections:

$P=\frac{P_1+P_2}{2}$

In formula,

P is supercritical carbon dioxide average pressure in measuring line sections pipe, MPa；

P₁The pressure of line sections Guan Nei import department, MPa is being measured for supercritical carbon dioxide fracturing fluid；

P₂The pressure at line sections pipe inner outlet, MPa is being measured for supercritical carbon dioxide fracturing fluid；

(5) supercritical carbon dioxide fracturing fluid flow velocity in measuring line sections, is calculated

Supercritical carbon dioxide fracturing fluid mass flow Q of reading quality flowmeter, calculates overcritical titanium dioxide Carbon fracturing fluid flow velocity in measuring line sections:

Z³-(1-B)Z²+(A-3B²-2B)Z-(AB-B²-B³)=0

$A=0.45724\left(\frac{{\[1+(0.37464+1.5226w-0.26992w^2)\left(1-T_r^{0.5}\right)\]}^2{p}_r}{T_r^2}\right)$

$B=0.077796\left(\frac{p_r}{T_r}\right)$

${\mathrm{\ρ}}_{{\mathrm{CO}}_2}=\frac{{\mathrm{PM}}_g}{ZRT}$

$\mathrm{\ρ}={\mathrm{\ρ}}_{{\mathrm{CO}}_2}{x}_{{\mathrm{CO}}_2}+{\mathrm{\ρ}}_t{x}_t$

$u=\frac{4Q}{{\mathrm{\ρ\πD}}^2}$

In formula,

Z is compressibility factor, dimensionless；

p_rFor reduced pressure, dimensionless；

T_rFor reduced temperature, dimensionless；

W is the eccentric factor of carbon dioxide, dimensionless；

ρ_CO2For the density of carbon dioxide, kg/m³；

x_CO2For carbon dioxide ratio in supercritical carbon dioxide fracturing fluid, dimensionless；

ρ_tFor the density of tackifier, kg/m³；

ρ is the density of supercritical carbon dioxide fracturing fluid, kg/m³；

x_tFor tackifier ratio in supercritical carbon dioxide fracturing fluid, dimensionless；

P is absolute pressure, MPa；

T is absolute temperature, K；

M_gFor the molecular weight of carbon dioxide, kg/m³；

R is universal gas constant, 0.008314MPa m³/(kmol·K)；

Q is the mass flow of supercritical carbon dioxide fracturing fluid, kg/s；

D is for measuring line sections diameter, m；

U is supercritical carbon dioxide fracturing fluid flow velocity in pipeline, m/s；

(6), wall shear stress is calculated

Read the pressure differential Δ p measuring line sections differential pressure pick-up, be calculated wall shear stress:

${\mathrm{\τ}}_w=\frac{D\mathrm{\Δ}p}{4L}$

In formula,

τ_wFor wall shear stress, Pa；

Δ p is the pressure differential measuring line sections differential pressure pick-up, Pa；

L is the length measuring line sections, m.

(7) constitutive relation of supercritical carbon dioxide fracturing fluid fluid rheology parameter, it is calculated

At τ_w—Draw logarithmic curve on coordinate, obtain corresponding different τ_wSlope of curve n', and then obtain The constitutive relation of supercritical carbon dioxide fracturing fluid fluid rheology parameter:

$\stackrel{\·}{\mathrm{\γ}}=(\frac{3}{4}+\frac{1}{4n^{\′}})\frac{8u}{D}$

$n^{\′}=\frac{dln\left(\frac{D\mathrm{\Δ}p}{4L}\right)}{dln\left(\frac{8u}{D}\right)}$

In formula,

For supercritical carbon dioxide fracturing fluid fluid shearing rate of deformation, s^-1；

N' is different τ_wThe logarithmic coordinates slope of curve.

The method of measurement supercritical carbon dioxide fracturing fluid rheological characteristic the most according to claim 6, its It is characterised by, changes the temperature of experimental system, pressure, thus study supercritical carbon dioxide fracturing fluid rheology Property is with temperature, the Changing Pattern of pressure.