SY/T 5107-1995 Performance evaluation method of water-based fracturing fluid
Some standard content:
Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/T 5107 - 1995
Evaluation Method of Water-Based Fracturing Fluid Performance
Published on December 25, 1995
China National Petroleum Corporation
Implementation on June 30, 1996
Cited Standards
Instruments, Equipment and Reagents
Preparation of Fracturing Fluid Samples
6 Determination Method of Fracturing Fluid Performance
Appendix A (Appendix to the Standard)
Appendix B (Suggestive Appendix)
Appendix (Suggestive Appendix) ）
Appendix D (Suggested Appendix)
Fracturing fluid performance test result table format
Conversion between rotational viscometer and K, n, values in pipelines or cracks Rotational viscometer test description
Core permeability damage rate test description
Based on the development of fracturing fluid technology research, the introduction of advanced technology, the updating of instruments and equipment, and some problems in the implementation of the original standard, this standard has revised SY5107-86 "Recommended Practice for Evaluation of Water-Based Fracturing Fluid Performance". This standard retains the main contents of the original standard that have been proven to be suitable for the performance test methods of fracturing fluids in my country for many years. However, with the development of fracturing fluid technology research in my country: the performance of fracturing fluids has been continuously improved and improved. In order to more comprehensively determine the performance of fracturing fluids, the method for measuring the surface tension and interfacial tension of degelling fluids using a surface tension meter, the method for measuring the cross-linking time of fracturing fluids, and the method for measuring the drag reduction rate have been added. Due to the update of test instruments and equipment, the method for measuring the rheology of fracturing fluids with an RV viscometer has been added. The study on the mechanism of damage to the permeability of the core matrix by fracturing fluid shows that the invasion of fracturing fluid filtrate and the physical and chemical changes of the filtrate in the pores and throats of the formation are the main causes of damage to the permeability of the matrix of the fracturing formation. Therefore, the determination method of the damage to the matrix permeability by fracturing fluid has been revised, and the determination methods of water content and water insoluble matter in the powder in the original standard have been deleted. The RV, rheological properties and pipeline friction resistance determination methods and some contents in the appendix have also been deleted, and some chapters and articles have been supplemented and adjusted. Compared with the original standard, this standard has changed the contents of chapters and articles. : This standard will replace SY5107-86 from the month of entry into force. Appendix A of this standard is the appendix of the standard; Appendix B, Appendix C and Appendix D of this standard are all prompts. This standard is proposed and managed by the Oilfield Chemistry Professional Standardization Technical Committee. Drafting units of this standard: Oil Production Engineering Research Institute of Petroleum Exploration and Development Science Research Institute, Fracturing Acidizing Center of Langfang Branch of Petroleum Exploration and Development Science Research Institute.
The main drafters of this standard are Guan Changzhi, He Binglan, Lu Yongjun, Cui Mingyue, 1 Fan Quan
People's Republic of China Petroleum and Natural Gas Industry Standard Water-based Fracturing Fluid Performance Evaluation Method
This standard specifies the performance determination method of water-based gel fracturing fluid. This standard is applicable to the performance determination and evaluation of thickened water fracturing fluid. 2 Referenced Standards
SY/T 5107—1995
Replaces SY5107—86
The clauses contained in the following standards constitute the clauses of this standard through reference in this standard. All versions are valid when this standard is published. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T6541---86Petroleum productsDetermination of interfacial tension of oil against water (ring method)SY/T 5336—88
Recommended practice for conventional core analysis
Sesbania sesbania fracturing fluid
SY/T 5341--88
Surface and interfacial tension determinationHanging plate method
SY/T 5370—91:
3Surface (interface) tension determination methodPendant drop methodSY/T 5617—93
SY/T 6074—94
3Definitions
Methods for determination of properties of plant gum and its modified productsThis standard adopts the following definitions only.
3.1 Final filtration
The total amount of liquid filtered out of the fracturing fluid through the filter paper or core at the specified experimental temperature, pressure and time, mL, expressed in Qt. 3.2First fittration
is the filtration loss per unit area at time zero, that is, on the rectangular coordinates, draw a curve with the filtration loss as the ordinate and the square root of the filtration time as the abscissa, take the straight line segment to extend, and get the intercept that intersects with the ordinate. The ratio of the intercept to the filtration area is m/m, expressed as Q.
3.3Filtration ratefiltrationrate
The filtration loss per unit area within the unit filtration time, m/min, expressed as ve. 3.4Filtration coefficientfiltrationcoefficientThe filtration loss per unit area within the square root of the filtration time, m/Vmin, expressed as C. 3.5Core matrix permcability damage ratioThe percentage of the permeability change value before and after the core is squeezed into the fracturing fluid filtrate to the core matrix permeability under certain temperature and pressure difference conditions, expressed as %.
4 Instruments and reagents
4.1 Pharmaceutical balance; sensitivity 0.1g
4.2 Electronic balance: sensitivity 0.0001g.
4.3 Stirrer: Waring mixer or similar product, electric stirrer. Approved by China National Petroleum Corporation on December 25, 1995, implemented on June 30, 1996
SY/T 5107-:1995
4.4 Viscometer: Fan 50C, RV, RVc rotary viscometer, Fan 35 or six-speed rotary viscometer, Pinnacle capillary viscometer. 4.5 AC regulated power supply: rated power 1kVA. 4.6 Voltage regulating transformer: rated power 1kVA. 4.7 Electric constant temperature water bath: working temperature is room temperature ~ 100℃ ± 1'C. 4.8 Electric heating temperature drying oven: the upper working temperature is room temperature ~ 200 ℃ ± 1 ℃ or 250 ℃ ± 1 ℃. 4.9 Gas permeability tester.
High temperature and high pressure core flow tester.
High temperature and high pressure filter loss meter and matching N0)988 filter paper or similar products. Vacuum pump: exhaust flow 2~41-/s, rated vacuum degree 6.66×10-2Pa. 4. 12
Centrifuge: speed 0~4000r/min, matching centrifuge tube, its capacity is 50ml. Ring method interface tension meter: in accordance with the provisions of GB/T6541. Hanging plate method interface tension meter: in accordance with the provisions of SY/T5370. Hanging drop method interface tension meter: in accordance with the provisions of SY/T5617. 4.16
Density meter: accuracy ± 0.0001g/cm.
Glass filter funnel: 00G”, 00G”. 4.18
Biological microscope.
Potassium chloride, sodium chloride, magnesium chloride, calcium chloride: all are chemically pure reagents. 5 Preparation of fracturing fluid samples
5.1 Requirements for sample preparation
Describe the name of the fracturing fluid, its components, dosage, ratio, order of entry, requirements for preparation water, and the preparation conditions and special requirements.
5.2 Preparation of base fluid
Prepare the base fluid with rubber powder, modified products and polymer dry powder. Accurately weigh or measure the required powders and additives according to the ratio, put them into the mixer filled with 500ml of test water, stir them at a low speed, so that the required powders and additives can be added slowly in sequence, and then use the voltage-regulating transformer to adjust the voltage to 50-55V, so that the mixer stirs at a high speed of 6000r/min±200r/min for 5min to form a uniform solution, pour it into a beaker, cover it, and put it in a constant temperature 30℃ water bath pot for 4h to make the base liquid viscosity tend to be stable. 5.3 Preparation of gel
5.3.1: Prepare the crosslinking agent solution of the required concentration according to the ratio requirements. Measure the crosslinking agent solution according to the crosslinking ratio, take 500ml of the base liquid prepared in 5.2 and pour it into the mixer, adjust the voltage to make the mixer stirrer rotate, so that the liquid surface forms a vortex until the bottom of the vortex sees the top of the stirrer. Make the stirrer rotate at a constant speed, then pour the cross-linking liquid in and stir in the mixer. The vortex will gradually disappear until the liquid surface slightly bulges, forming a uniform gel that can be picked up. 5.3.2 Preparation of one-step forming gel: Accurately weigh and measure the required chemical additives such as enhancers, crosslinking agents, preservatives, surfactants, etc. according to the ratio, measure the test water required for preparing 500mlL gel, pour it into the Haoyin mixer, control the voltage at 50-55V, make the mixer stir at a speed of 600r/min±200r/min, slowly add the various chemicals used into the mixer in sequence, and stir quickly after adding until the liquid surface is slightly blocked to form a uniform gel that can be picked up. 6 Fracturing fluid performance measurement method
The following measurement results are all filled in the fracturing fluid performance measurement result table, and its format is shown in Appendix A (Standard Appendix). 6. Base fluid apparent viscosity measurement
Use the base fluid prepared in 5.2 for measurement, and perform it according to 6.4 in SY/T6074-94. 6.2 Rheological property measurement
The rheological property measurement of fracturing fluid is to regard the fracturing fluid as a pseudoplastic fluid. 2
6.2.1RV, Viscometer Determination Method
6.2.1.1 Determination of K,,n Value of Fracturing Fluid
SY/T 5107—1995
Put the fracturing fluid into the sample cup according to the test requirements, preheat the water bath to the required test temperature, and start calculating the constant temperature time after the temperature of the heating jacket outside the sample cup reaches the test temperature. When the selected constant temperature time is reached and the measurement begins, refer to Table C1 in Appendix C (Suggested Appendix). During the measurement, the shear rate is from low to high, and the instrument is rated for a gear 1 to 8. When the shear time at each level is 1min, an initial flow curve is measured, and the shear rate range is 0~145.8s-1. Then, at a shear rate of 145.8s-1, the fracturing fluid is subjected to long-term continuous shear. A flow curve is measured every half an hour until the apparent viscosity of the fracturing fluid is 50mPa·s and the measurement is stopped. The measurement time can also be determined according to the construction time of the fracturing operation. The value of K1 is the arithmetic mean of the K1 values of the measured flow curves, and can also be selected according to the process design requirements. 6.2.1.2 Pre-shear stability measurement
After the sample is installed, an initial flow curve is measured at the beginning according to the method of 6.2.1.1, and the shear rate range is 0~~145.8s-1. Then, at a shear rate of 145.8s-1, the fracturing fluid is subjected to long-term continuous shear until the apparent viscosity of the fracturing fluid is 50mPa·s and the measurement is stopped. The shear stability is characterized by the trend of the apparent viscosity changing with the shear time, The shear time can also be defined as the construction time of the fracturing operation. 6.2.1.3 Determination of thermal stability
After the fracturing fluid is installed and heated to the required measuring temperature, the fracturing fluid is sheared at a fixed shear rate (generally 145.8s-\), the shear time is 1min, and the relative stability value is read. Then the temperature is kept constant for 30min or 60min, and then sheared for 1min, and this is repeated in sequence until the apparent viscosity of the fracturing fluid reaches 50mPa·s. The trend of the change of the apparent viscosity with the constant temperature time is used to characterize the thermal stability, and the measuring temperature is selected as the applicable temperature for the fracturing fluid.
6.2.1.4 Data processing
) Find the shear rate values at different rotation speeds from the grade table given by the instrument. b) Find the circular cylinder coefficient of the shear rate range corresponding to the measuring disc system from the given grade table, and the stress value at each shear rate is calculated according to formula (1):
Where: t--shear stress at the inner cylinder radius of the instrument, MPa7 ----Cylinder coefficient;
fe——Indicator reading.
c) Use t, D, to draw a graph on a double logarithmic coordinate, with t, as the ordinate and force, as the abscissa, to draw a flow curve, and take the logarithm of the intercept of the straight line segment that intersects the ordinate as K, and the slope as nK. The value of n can also be calculated by linear regression. d) Calculate the apparent viscosity according to formula (2):
P=× 100
Where: 了—instrument power frequency, Hz; u apparent viscosity, mPa·s
D, shear rate, s\l.
6.2.2RVz viscometer determination method
6.2.2.1 Determination of K, n values of fracturing fluid
Test procedure setting: During the heating process of the fracturing fluid sample, the heating rate is 3.0'C/min±0.2! tmnin, and the rotor rotates at a shear rate of 3s; when the temperature rises to the set test temperature, the rotor speed increases, so that the shear rate gradually increases from 3s- to 170s-\, and then the rotor speed is reduced, and the shear rate decreases from 170s- to 3s-!, and the variable shear rate measurement time is 6min; then jump to the shear rate of 170s to continue shearing, and repeat the variable shear rate test every 0.5h. The number of repetitions is determined according to the construction time of the fracturing operation. Determination method: Fill the sample container with the required amount of fracturing fluid, heat the sample with a high-temperature oil bath, and rotate the rotor at a low speed to make the sample heated evenly. Perform automated testing according to the test setting program. 3
K, n values are taken according to 6.2.1.1.
6.2.2.2 Determination of shear stability
SY/T S107—1995
After the fracturing fluid sample is filled, heat the sample at a heating rate of 3.0C/min±0.2℃/min, rotate the rotor, and the shear rate is 3s! , and start the measurement when the sample reaches the measurement temperature. Increase the rotor speed, and when the shear rate reaches 170s-, continue shearing until the apparent viscosity of the fracturing fluid is 50mPa*, stop the measurement, and determine the shear stability of the fracturing fluid by the trend of apparent viscosity changing with shear time. The shear time can also be set as the construction time of the fracturing operation, and the measurement temperature is the applicable temperature of the fracturing fluid. 6.2.2.3 Determination of thermal stability
After the fracturing fluid is loaded, heat the sample according to the above requirements. When the sample reaches the test temperature, shear the rotor at a shear rate of 170s-1 for 1min, then keep it at a constant temperature for 30 or 60min, shear it for 1min, and then keep it at a constant temperature. This is done in sequence until the apparent viscosity of the fracturing fluid reaches 50mPa. Stop the test at this time. The thermal stability of the fracturing fluid is determined by the change trend of the apparent viscosity with the constant temperature time. The test temperature is the applicable temperature of the fracturing fluid. 6.2.2.4 Determination of temperature resistance
After the fracturing fluid is loaded, heat the sample and control the heating rate to 3/min+0.2'C/min. At the same time, the rotor rotates at a shear rate of 170s-1. The fracturing fluid is continuously sheared under the heating condition until the apparent viscosity of the fracturing fluid reaches 50mPa·S at a certain temperature. The temperature resistance of the fracturing fluid is measured by the change value of the apparent viscosity with the increase of temperature. 6.2.2.5 Data processing
The shear rate D is calculated according to formula (3):
D, = D.× N
The shear stress is calculated according to formula (4):
t, = tre XS
The apparent viscosity is calculated according to formula (5);
μ (r./D) ×1000
The rheological parameter K and n are calculated according to the curtain law fluid formula (6): -R. XD
Where: D·the shear rate per revolution. s\N Instrument speed, r/min
T\\—shear stress, Pa;
—Instrument coefficient;
S—Instrument reading.
K.—Coefficient of consistency, mPas\;
n—Flow behavior index:
All the above parameters are automatically calculated by the computer software program and the calculation results are output. 6.2.3 Determination method of 50C viscometer
6.2.3.1 Determination of fracturing fluid K,. # value
The sample cup needs to be filled with fracturing fluid and heated with a high-temperature oil bath. During the heating process, the sample cup rotates at a speed of 2 to 5r/min to make the sample heated evenly. When the measuring temperature is above 90℃, pressure needs to be applied to the sample before heating. The pressure value is given according to the instrument manual. When the sample reaches the required temperature, the measurement is carried out. The drum speed is from low to high. At each speed, the fracturing fluid is sheared continuously for 1 minute, and then switched to the next specified speed for shearing until the shear rate is 170s, and the relatively stable value of the shear time is 1min is read. An original flow curve is measured with a shear rate of 0 to 170s-; then the shearing is continued at a shear rate of 170s-, and a flow curve is measured every 0.5h until the apparent viscosity of the fracturing fluid is 50mPa·5. The measurement time can also be determined according to the construction time of the fracturing operation, and the measurement temperature is the applicable temperature of the fracturing fluid. Speed selection: According to the corresponding drum speed of shear rate of 3, 5, 9, 16, 27, 48, 81, 170s-. Measurement temperature: applicable temperature of fracturing fluid.
Measurement pressure: given according to the requirements of the instrument manual. 4
K and n values are taken according to 6.2. 1.1.
6.2.3.2 Shear stability determination
SY/T 5107---1995
After filling the fracturing fluid, heat and pressurize the sample. When the sample reaches the measurement temperature, start the measurement. First, press 6.2.3.1 Method Determine the original flow curve, and then continue to shear at a shear rate of 170s until the apparent viscosity of the fracturing fluid is 50mP·s, and then stop the measurement. The shear time, measurement temperature, and shear stability characterization are the same as 6.2.2.2. 6.2. 3.3 Thermal stability determination
After the fracturing fluid is loaded. Heat and pressurize the sample, and when the sample reaches the measurement temperature, rotate the drum at a shear rate of 170s'. The sample is sheared for 1min, read the relative stability value, and then keep the temperature constant for 30 or 60min, and then shear for 1min, and so on, until the apparent viscosity of the fracturing fluid is 50mPa·s, and then stop the measurement. The thermal stability characterization and measurement temperature are the same as 6.2.2.3. 6.2.3.4 Temperature resistance determination
After the fracturing fluid is loaded, heat and pressurize the sample, control the temperature rate to 3C/min + 0.2C/min, and rotate the drum at a shear rate of 170s. The fracturing fluid is subjected to continuous shearing until the apparent viscosity of the fracturing fluid reaches 50 mPa· at a certain temperature. The change in apparent viscosity with increasing temperature indicates the temperature resistance of the fracturing fluid. 6.2.3.5 Data processing
The shear rate D, is calculated according to formula (7):
D. =D. XN
The shear stress, is calculated according to formula (8):
The apparent viscosity is calculated according to formula (9):
μ(t./p,) × 1000
Where: D.—-the shear rate of one revolution of the drum, sT.—the stress value represented by each grid on the recording paper, MPa: M—the number of stress value grids on the recording paper.
Calculate the value of K, according to data processing in 6.2.1.4. The conversion of the values of K,n, in the rotational viscometer and pipeline or crack is in Appendix B (suggested appendix). 6.3 High temperature and high pressure static filtration test
Test the filtration of the fracturing fluid without proppant through the filter paper under high temperature and high pressure conditions. Test temperature: applicable temperature range of fracturing fluid. Test pressure: the instrument specifies the test pressure difference of 3.5MPa: the back pressure is determined according to the instrument requirements. 6.3.1 Adjust the temperature of the heating jacket so that the temperature of the heating jacket is 510℃ higher than the test temperature. 6.3.2 Fill in 300ml of fracturing fluid sample and be careful not to contaminate the "()" shaped seal ring. (7)
6.3.3 Carefully place a round filter paper on the "()" shaped seal ring, install the filter cartridge and put it into the heating jacket so that it sits on the pin at the bottom.
6.3.4 Heat and pressurize the sample. According to the test temperature requirements in the instrument manual, apply pressure and back pressure to the filter cartridge. The filter cartridge heating time is about 30 minutes. When the filter cartridge temperature reaches the test temperature, use a nitrogen pressure source to supply the predetermined pressure, then open the air inlet valve and loosen the valve stem thread by about half a turn.
6.3.5 Place a filter cartridge under the discharge valve stem and loosen the valve stem thread by half a turn to allow the filtrate to flow out. At the same time, record 1, 4, 9, 16, The filtration basis at 25, 30, and 36 minutes is accurate to 0.1 ml. During the measurement process, the temperature is allowed to fluctuate by ±15°C. 6.3.6 Calculation of filtration loss: Use the filtration loss data of the fracturing fluid on the filter paper, with the filtration loss as the ordinate and the square root of time as the abscissa, and draw a graph on a rectangular coordinate system.
If the relationship between the filtration loss basis and the square root of time is not a straight line passing through the origin on the true angle coordinate diagram, a straight line as good as possible is given through the points with filtration loss times of 9, 16, and 25 minutes. The line segment is extended to intersect with the Y axis, and the intercept h at time zero is obtained. The slope of the straight line segment is m. The filtration coefficient C, filtration rate, and initial filtration loss Q5r controlled by the filter cake are calculated according to formulas (10), (11), and (12) 5
SY/T 5107—1995
Cs = 0. 005 X
Where: m——slope of the filtration curve, mL//min; A——filtration area, cm;
Ca——filter cake control filtration coefficient, m/Vmin; U—filtration velocity, m/min,
h-intercept of the straight segment of the filtration curve with the Y axis, cm\; Qsp-initial filtration loss, m/m2
t—filtration time, min.
6.4 Determination of the damage rate of fracturing fluid filtrate to the core matrix permeability 6.4.1 Experimental preparation
6.4.1.1 Core selection and preparationbzxz.net
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It is best to use natural cores obtained from the formation to be fractured. If not available, other formations or outcrop cores with similar permeability, porosity and lithology to the formation to be fractured can also be used, or artificial cores with similar lithology as the above can be made for trial. Test. Natural cores should be drilled from the same direction as the oil layer fluid flow, with both ends polished and perpendicular to the smooth column surface. The core diameter is 25~25.4mm or 37~～38mm, and the core length is 11.5 times the diameter. The core must be thoroughly washed of oil. The core cleaning is carried out according to 4.5.1 of SY5336-88, and the core drying is carried out according to 4.6 of SY5336-88. 6.4.1.2 Preparation and treatment of standard brine
a) Composition of standard brine
2.0%KC1-5.5%NaCl+0.45%MgCl+0.55%CaClh) Preparation steps
According to the composition and concentration requirements, accurately weigh the required KCl, NaCl, MgCl., CaCl, and add them to the required amount of distilled water. It can be heated appropriately and stirred continuously until it is completely dissolved. c) Standard brine treatment
Filter the prepared standard brine with a 100G glass filter funnel and use a vacuum pump to degas for 1 hour. 6.4.1.3 Kerosene treatment
Use experimental kerosene as the simulated oil. Treat the kerosene with silicon powder or activated clay to remove the moisture and impurities in the kerosene. Then filter it with a 100G glass filter funnel and use a vacuum pump to degas for 1 hour. 6.4.1.4 Determination of core gas permeability
Perform according to Chapter 7 of SY 5336-88. 6.4.1.5 Core saturation and pore volume determination a) Place the extracted and dried core that has been constant in weight into a vacuum desiccator and use a vacuum pump to evacuate and degas. When the vacuum degree is lower than 133.Pa, evacuate for 2 to 8 hours. For cores with particularly low permeability, the evacuation time needs to be appropriately extended. b) Slowly introduce the filtered, evacuated and degassed brine into the vacuum dryer. The core is gradually saturated with brine until the core is completely immersed in the liquid. Continue to evacuate for 1 hour to increase the core saturation. After stopping the evacuation, slowly open the vacuum dryer to the atmosphere. After the core returns to atmospheric pressure, soak for at least 1 hour. c) Take out the core, quickly wipe off the liquid on the surface of the core with filter paper and weigh it. The pore volume of the core is equal to the difference between the mass of the core after saturation with liquid and the mass before saturation divided by the density of saturated liquid. 6
SY/T 5107--1995
6.4.1.6 Preparation of fracturing fluid filtrate
According to the determination method in 6.3, increase the filtration time and collect all the fracturing fluid filtrate. 6.4.2 Determination of core matrix permeability
6.4.2.1 Squeeze salt water through the core
Put the core into the high temperature and high pressure core flow tester, connect the test process, and squeeze the salt water into the lower end of the core and flow out from the upper end. The squeeze pressure difference is 0.7MPa. According to the core permeability, the squeeze pressure difference can be appropriately increased or decreased. The amount of salt water passing through is required to be 10 times the pore volume to further saturate the core with salt water. 6.4.2.2 Measurement of kerosene permeability through the core K1 Squeeze kerosene into the core from the lower end of the core to displace the salt water in the core pores until all the kerosene is discharged. After the kerosene flow rate is stable, measure its flow rate so that the measured permeability error does not exceed 2%. The test pressure difference is selected as 0.7, 1, and 1.4MPa. Select one of the pressure difference values according to the core permeability. See Appendix D (Suggested Appendix). 6.4.2.3 Squeeze the fracturing fluid filtrate into the core
Put the fracturing fluid filtrate into a high-pressure container and pressurize it with a pressure source so that the filtrate enters the core from the upper inlet of the core holder (opposite to the direction of squeezing brine and kerosene). The squeezing pressure difference can be selected as 0.7, 1, 1.4MPa according to the core permeability. The amount of filtrate squeezed into the core is limited to 36min, and the volume is measured at 1, 4, 9, 16, 25, 30, 36min. After squeezing, close the valves at both ends of the holder and let the filtrate stay in the core for 2h. The test temperature is the applicable temperature of the fracturing fluid. 6.4.2.4 Measure the permeability K of kerosene through the core. After the core cools to room temperature, measure the kerosene permeability K of the core after being damaged by the fracturing fluid filtrate according to the method in 6.4.2.2. The displacement amount of kerosene is required to be 5 to 15 times the pore volume.
6.4.2.5 Core permeability K, K2 during water injection well fracturing Core permeability K1, K2 during water injection well fracturing were measured using salt water. 6.4.3 Data processing
6.4.3.1 The core permeability is calculated according to formula (13): QXμXL
Wherein: K is the permeability of kerosene or brine through the core, um; Q is the volume flow rate of kerosene or brine through the core, mL/sI. is the axial length of the core, cm,
A is the cross-sectional area of the core, cm
μ is the viscosity of kerosene or brine, mPa·s; A force is the pressure difference between the upstream and downstream of the core, MPa. 6.4.3.2 The matrix permeability damage rate is calculated according to formula (14): Ki-K2 × 100
Wherein: na-—permeability damage rate.%:
K-the matrix permeability before the core extrusion fracturing fluid filtrate, um\: K,-the damaged permeability of the core extrusion fracturing fluid filtrate, um6.5 Determination of fracturing fluid gel breaking performance
The gel breaking speed of the fracturing fluid and the time of complete gel breaking are measured to provide a reference for the fracturing fluid backflow during fracturing construction. (13)
Put 50ml of fracturing fluid into a sealed container and heat it in the main electric thermostat to a constant temperature. The constant temperature is the oil layer temperature. The fracturing fluid is broken at a constant temperature, and the clear liquid above is taken to measure the viscosity: 6.5.1 Determination of gel breaking fluid viscosity
The gel breaking fluid viscosity is measured using a Persian capillary viscometer according to the operating instructions. The measuring temperature is 30℃ or equal to the wellhead oil outlet temperature. 7
The viscosity of the gel-breaking liquid is less than 10mPa*s and is qualified. 6.S.2 Determination of surface and interfacial tension of gel-breaking liquid SY/T 5107--1995
The surface and interfacial tension of the gel-breaking liquid of the micro-fluid is measured to provide a reference for the optimization of suitable surfactants and drainage aids, thereby improving the return rate of the fracturing fluid.
a) Ring method
The interface between kerosene and gel-breaking liquid is used as the oil-water interface and measured according to GB/T6541. b) Hanging plate method
The clear liquid of the gel-breaking liquid of the fracturing fluid is measured according to SY/T5370. c) Spinning drop method
The clear liquid of the gel-breaking liquid of the fracturing fluid is measured according to SY/T5617. 6.6 Determination of residue content of fracturing fluid
The residue is the insoluble matter remaining in the conventional gel-breaking liquid of the fracturing fluid. Determine the base content of the residue to provide a reference for reducing oil layer damage and improving the dissolution capacity of fractures:
6.6.1 Take the test water and the field water, and prepare the frozen gel fracturing fluid according to 5.2 and 5.3 respectively. Weigh 50g, whose apparent density is 1z/cm2, and consider 50ml, put it into a stainless steel container and heat it to constant temperature to break the gel. The constant temperature is the oil layer temperature, and the constant temperature time is the time for the fracturing fluid to completely break the gel. The fracturing fluid is completely broken into broken gel liquid.
6.6.2 Pour all the broken gel liquid into a centrifuge tube that has been dried to a constant volume, put the centrifuge tube into a centrifuge, and centrifuge it at a speed of 3000r/min for 3min, then slowly pour out the upper layer of liquid, and then wash the stainless steel container with 50mL of water and pour it into the centrifuge tube. Stir the washed porcelain residue sample with a glass rod, and then put it into the centrifuge for centrifugation. 20min, pour out the upper clear liquid, put the centrifuge tube into the constant overflow electric heating drying oven and bake it at a temperature of 105 (21C) until it is clear. 6.6.3 The residual content of the fracturing fluid is calculated according to formula (15): m
Formula: 7a——Fracturing fluid residual content, mg/.; m. Residue mass, mg!
V—Fracturing fluid dosage, I.
It is required to make two samples in parallel, and the error of the measurement result shall not exceed 0.5%. The arithmetic mean value of the result is taken. 6.7 Determination of compatibility between fracturing fluid and formation fluid (15)
Determination of compatibility between fracturing fluid degelling liquid and formation fluid Whether the reaction between the crude oil and the formation water can produce emulsification and precipitation, so as to take measures to reduce the damage to the formation permeability.
6.7.1 Mix the crude oil and the Le cracking liquid in a volume ratio of 3:1, 3:2, and 1:1 respectively, with a total liquid volume of 50mL, put it into a container and place it in a dry electric constant temperature water bath, heat and keep the constant temperature. The constant temperature is the fracturing formation temperature. If the formation temperature is greater than 95℃, 95℃ is used. Increase the stirrer speed gradually to 140or/min and stir at a constant speed for 5min, then pour all the liquid into a graduated colorimetric tube and record the actual volume of the emulsion. Volume: Take a sample and observe the type of emulsion under a microscope. 6.7.2 Place the stoppered graduated colorimetric tube containing the emulsion in a constant temperature water bath and let it stand until it warms up. The constant temperature is the same as in 6.7.1. Record the volume of the degelling liquid separated at 3, 5, 10, 15, 30, 60 min and 2, 4, 10, 24 h respectively. 6.7.3 The emulsification rate and demulsification rate are calculated according to formulas (16) and (17): 100
Where: - emulsification rate of crude oil and degelling liquid, %; V2
—— demulsification rate of emulsion of crude oil and degelling liquid, %; R
SY/T 5107—1995
V—Total volume of degelling liquid used for emulsification, nml; V,-V is the volume of emulsified degelling liquid, mI.
V2-V, is the volume of degelling liquid removed, ml. 6.7.4 Mix degelling liquid with formation water in a volume ratio of 1:2, 11, 2:1, with a total liquid volume of 60ml, and observe whether precipitation is produced. 6.7.5 Method for dehydrating water-containing crude oil: If the crude oil contains water, simple dehydration is required. Pour the water-containing crude oil into a flask and heat it in an electric constant temperature water bath. The constant temperature is generally about 20°C higher than the freezing point of the crude oil. Keep the constant temperature until the amount of water removed remains unchanged. Take the upper sample of the dehydrated crude oil for compatibility determination.
6.8 Determination of cross-linking time of fracturing fluid
For fracturing fluid with delayed cross-linking, the cross-linking time should be determined to provide a basis for on-site construction. According to the method of preparing gel in 5.3.1, use a stopwatch to record the time when the crosslinking agent solution is poured into the mixer until a uniform gel fracturing fluid is formed. 6.9 Determination of drag reduction rate of fracturing fluid
Measure the pressure drop of fracturing fluid without proppant and clean water flowing in the oil pipe, so as to determine the drag reduction rate of fracturing fluid. The determination method is carried out according to 9.3 of SY5341-88..
It is required to make two samples in parallel, and the error of the test results shall not exceed 0.5%. The arithmetic mean of the results shall be taken. 6.7 Determination of compatibility between fracturing fluid and formation fluid (15)
Determine whether the fracturing fluid degelling liquid can produce emulsification and precipitation when reacting with formation crude oil and formation water, so as to take measures to reduce its damage to formation permeability.
6.7.1 Mix crude oil and fracturing fluid degelling liquid in a volume ratio of 3:1, 3:2, and 1:1 respectively, with a total liquid volume of 50mL. Put them into a container and place it in a dry electric constant temperature water bath. Heat to a constant temperature. The constant temperature is the fracturing formation temperature. If the formation temperature is greater than 95℃, 95℃ is used. Increase the stirrer speed gradually to 140or/min and stir at a constant speed for 5min. Then pour all the liquid into a graduated colorimetric tube and record the actual volume of the emulsion: Take a sample and observe the type of emulsion under a microscope. 6.7.2 Place the stoppered graduated colorimetric tube containing the emulsion in a constant temperature water bath and let it stand until it warms up. The constant temperature is the same as that in 6.7.1. Record the volume of the degelling liquid separated at 3, 5, 10, 15, 30, 60 min and 2, 4, 10, 24 h respectively. 6.7.3 Calculate the emulsification rate and demulsification rate according to formula (16) and (17): 100
Where: - emulsification rate of crude oil and degelling liquid, %; V2
—— demulsification rate of emulsion of crude oil and degelling liquid, %; R
SY/T 5107—1995
V—total volume of degelling liquid used for emulsification, nmL; V,-volume of emulsified degelling liquid in V, ml.
V2-V, volume of degelling liquid separated from V, mL. 6.7.4 Mix the degelling liquid with formation water in a volume ratio of 1:2, 11, 2:1, with a total liquid volume of 60 ml, and observe whether precipitation occurs. 6.7.5 Dehydration method of water-containing crude oil: If the crude oil contains water, simple dehydration is required. Pour the water-containing crude oil into a flask and heat it in an electric constant temperature water bath. The constant temperature is generally about 20°C higher than the freezing point of the crude oil. Keep the constant temperature until the amount of water removed remains unchanged. Take the upper sample of the dehydrated crude oil for compatibility determination.
6.8 Determination of cross-linking time of fracturing fluid
For delayed cross-linking fracturing fluid, the cross-linking time should be measured to provide a basis for on-site construction. According to the method of preparing gel in 5.3.1, use a stopwatch to record the time from the cross-linking agent solution being poured into the mixer until a uniform gel fracturing fluid is formed. 6.9 Determination of drag reduction rate of fracturing fluid
The pressure drop of fracturing fluid without proppant and clean water flowing in the oil pipe is measured to determine the drag reduction rate of fracturing fluid. The determination method is carried out according to 9.3 of SY5341-88..
It is required to make two samples in parallel, and the error of the test results shall not exceed 0.5%. The arithmetic mean of the results shall be taken. 6.7 Determination of compatibility between fracturing fluid and formation fluid (15)
Determine whether the fracturing fluid degelling liquid can produce emulsification and precipitation when reacting with formation crude oil and formation water, so as to take measures to reduce its damage to formation permeability.
6.7.1 Mix crude oil and fracturing fluid degelling liquid in a volume ratio of 3:1, 3:2, and 1:1 respectively, with a total liquid volume of 50mL. Put them into a container and place it in a dry electric constant temperature water bath. Heat to a constant temperature. The constant temperature is the fracturing formation temperature. If the formation temperature is greater than 95℃, 95℃ is used. Increase the stirrer speed gradually to 140or/min and stir at a constant speed for 5min. Then pour all the liquid into a graduated colorimetric tube and record the actual volume of the emulsion: Take a sample and observe the type of emulsion under a microscope. 6.7.2 Place the stoppered graduated colorimetric tube containing the emulsion in a constant temperature water bath and let it stand until it warms up. The constant temperature is the same as that in 6.7.1. Record the volume of the degelling liquid separated at 3, 5, 10, 15, 30, 60 min and 2, 4, 10, 24 h respectively. 6.7.3 Calculate the emulsification rate and demulsification rate according to formula (16) and (17): 100
Where: - emulsification rate of crude oil and degelling liquid, %; V2
—— demulsification rate of emulsion of crude oil and degelling liquid, %; R
SY/T 5107—1995
V—total volume of degelling liquid used for emulsification, nmL; V,-volume of emulsified degelling liquid in V, ml.
V2-V, volume of degelling liquid separated from V, mL. 6.7.4 Mix the degelling liquid with formation water in a volume ratio of 1:2, 11, 2:1, with a total liquid volume of 60 ml, and observe whether precipitation occurs. 6.7.5 Dehydration method of water-containing crude oil: If the crude oil contains water, simple dehydration is required. Pour the water-containing crude oil into a flask and heat it in an electric constant temperature water bath. The constant temperature is generally about 20°C higher than the freezing point of the crude oil. Keep the constant temperature until the amount of water removed remains unchanged. Take the upper sample of the dehydrated crude oil for compatibility determination.
6.8 Determination of cross-linking time of fracturing fluid
For delayed cross-linking fracturing fluid, the cross-linking time should be measured to provide a basis for on-site construction. According to the method of preparing gel in 5.3.1, use a stopwatch to record the time from the cross-linking agent solution being poured into the mixer until a uniform gel fracturing fluid is formed. 6.9 Determination of drag reduction rate of fracturing fluid
The pressure drop of fracturing fluid without proppant and clean water flowing in the oil pipe is measured to determine the drag reduction rate of fracturing fluid. The determination method is carried out according to 9.3 of SY5341-88.
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