Summary of the invention
To solve the problem in the prior art, the present invention provides a kind of stepless variable element ramp type note of deep layer shale gasEnter fracturing process, by evaluation, the determination of thick perforating site, split waveguide, pressing crack construction of carrying out crucial shale parameterParameter optimization becomes viscosity slippery water and becomes the preparation of viscosity glue, perforation and the construction of lower bridge plug joint, low-kappa number operation, glueSeam or low-viscosity slippery water take the high construction of sand control seam, the main seam construction of low-viscosity slippery water, variable element injection and add sand construction,The series of steps such as operation are replaced, increase the synchronous crack initiation in more cluster cracks in section to the maximum extent and are closely uniformly extended, therefrom preferablyThe relatively optimal fracture parameters group of effect is combined into the fracture parameters and construction parameter of optimization after pressure, proposes the nothing for being stepped up viscosityPole degree of becoming sticky slippery water formula, to achieve the purpose that improve deep layer shale gas fracturing effect, increase yield.
Design object of the invention: change fracturing fluid viscosity, injection discharge capacity and construction sand liquor ratio at any time according to the actual situationAnd add four parameters such as sand model (slug formula or continous ways), to be continuously increased the net pressure in various scale cracks, continueIncrease the geometric dimension in cracks at different levels, and optimize the parameters such as proppant injection way and partial size, sand liquor ratio, makes filling for cracks at different levelsDegree of filling out maximizes, to obtain stable yields effect after relatively good pressure guaranteeing that initial production is higher simultaneously.
The object of the present invention is to provide a kind of stepless variable element ramp types of deep layer shale gas to inject fracturing process.
Include:
(1) evaluation of crucial shale parameter
(2) determination of shower hole site
(3) split waveguide
(4) optimization of fracturing parameter
(5) become the preparation of viscosity slippery water
Slippery water viscosity gradually increases between 2mPa.s~12mPa.s；The resistance-reducing yield of the slippery water of different viscositys exists65% or more；
(6) become the preparation of viscosity glue
Glue viscosity range gradually increases between 20-50mPa.s, the resistance-reducing yield of the glue of different viscositys all 60% withOn；
(7) perforation and lower bridge plug joint are constructed
(8) low-kappa number operation
(9) glue seam or low-viscosity slippery water take the high construction of sand control seam
(10) the main seam construction of low-viscosity slippery water
(11) variable element injection and plus sand construction
(12) operation is replaced
Wherein, preferably:
Step (5) slippery water viscosity gradually increases between 2mPa.s~12mPa.s；Between viscosity step take2mPa.s。
Step (6), glue viscosity range are 20-50mPa.s, select 7 kinds of viscositys.
In step (7), coiled tubing perforation under first segment, later cable pumps perforation and lower bridge plug；Shot density is 10-16 holes/m, single cluster perforating length are 1-1.5m, and aperture is 9.5mm or more.
Step (8), sour dosage are 10-20m3, discharge capacity 1-1.5m3/ min, acid inject after for acid discharge capacity be increased to 4-Discharge capacity is again decreased to 1.5~2m after acid reaches perforating site by 6m3/min3/ min, after waiting the 50% of acid to enter borehole, thenDischarge capacity is increased to 4-6m3/min.
Step (9),
Such as high angle intrinsic fracture agensis in target zone, 20-30m is taken3High viscosity glue seam；
If high angle intrinsic fracture is developed, injection early period 20-30m is carried out with low-viscosity slippery water3Afterwards, 4. discharge capacity takes stepThe 40%~50% of determining highest discharge capacity carries the extremely-low density powder pottery proppant of partial size 140-230 mesh, and construct sand liquor ratio 3-8%, step sand liquor ratio amplification 3%, powder pottery dosage 2-4m3, effectively to be blocked to high angle frature in the longitudinal direction.
The viscosity of step (9) the high viscosity glue is 50-60mPa.s；The viscosity of the low-viscosity slippery water is 1-2mPa.s；The apparent density of extremely-low density powder pottery proppant is 1~1.1g/cm3。
Step (10),
In seam up to after being expected to require, the low-viscosity slippery water that viscosity is 2mPa.s is used instead, dosage is the 20- of total liquid measure30%.
Step (11),
Slippery water viscosity increases to 12mPa.s from 2mPa.s；Glue viscosity increases to 50mPa.s from 20mPa.s；Slippery waterAfter injection, the injection of glue is then carried out；
Sand is added to execute since slippery water injection；There are two types of partial size, the proppant first is that 70-140 mesh powder is made pottery accounts for proppantThan 40-50%, the proppant second is that 40-70 mesh powder is made pottery, accounting 50-60%；First plus 70-140 purpose, then plus the branch of 40-70 meshSupport agent；
For the construction sand liquor ratio of 70-140 mesh proppant from 3% starting, sand liquor ratio amplification is 3%, and most takasago liquor ratio is 15%；
For the construction sand liquor ratio of 40-70 mesh proppant from 10% starting, sand liquor ratio amplification is 2%, and most takasago liquor ratio is 18%.
Step (12),
By the 110-130% design of this section of hole volume.
All stepless increase in the present invention, refer to the increase at the interval that do not fix, such as: range is 2- herein12, then must be not necessarily 2/4/6/8/10/12, can according to need be arbitrary interval, as long as being within this rangeCan, preferably equal steps increase.
Following technical scheme specifically can be used in the present invention:
Main construction procedure
1. the evaluation of crucial shale parameter
Including geologic sedimentation environment, lithology and sensibility, physical property, answer to rock mechanics and elastic-plastic deformation feature, three-dimensionalPower, high angle intrinsic fracture and horizontal bedding seam/texture seam development characteristics etc..
It can be used that well logging, well logging, the combination of the means such as test analysis determines in core chamber.The admission of attention parameters uses as far as possibleQuiescent value.Such as there was only result of log interpretation, to be converted with reference to offset well sound state transformational relation.
2. the determination of shower hole site
Step 1. on the basis of, carried out in conjunction with geology dessert and engineering dessert evaluation result it is integrated ordered, and after combiningTotal perforation number of clusters that continuous gas reservoir analog result determines carries out the fine of specific perforating site.It especially should engineering dessert is closePressure break is carried out as a section, to increase the synchronous crack initiation in more cluster cracks in section and the nearly purpose uniformly extended to the maximum extent.
3. split waveguide
It is simulated different using production forecast simulation softward ECLIPSE after mature shale air pressure by orthogonal design methodFracture length, flow conductivity, seam spacing and crack layout (wait the long intermediate short U-shaped distribution of the long distribution of seams, both ends and length seam to hand overMutual W type distribution etc.).The relatively optimal fracture parameters group of effect is combined into the fracture parameters of optimization after therefrom preferably pressing.
4. the optimization of fracturing parameter
In order to obtain the step 3. middle fracture parameters optimized, it is commercialized using mature shale gas fracturing fracture extended simulationSoftware MEYER simulates different fracturing parameters (containing discharge capacity, low-viscosity slippery water and high viscosity glue volume plus sand journeySequence, slippery water viscosity and glue viscosity etc.) under, Fracture geometric size situation of change therefrom can preferably reach the crack ginseng of optimizationFracturing parameter combination under several, is optimal fracturing parameter.
5. becoming the preparation of viscosity slippery water
Low-viscosity slippery water viscosity 2mPa.s, later, become viscosity slippery water highest viscosity take 12mPa.s, between viscosityStep can use 2mPa.s, that is, share the slippery water of 6 kinds of viscositys.It is operational convenient mainly to consider, should be theoretically to be stepped upThe electrodeless change viscosity slippery water of viscosity.
The resistance-reducing yield of the slippery water of different viscositys, with this preferred each additive types and dosage, should all be mentioned 65% or moreCorresponding formula out, convenient for being used when continuous mixture at the scene.
6. becoming the preparation of viscosity glue
It is 5. similar with step, but viscosity range is 20-50mPa.s, and viscosity step is 5mPa.s, that is, shares 7 kinds of viscositysGlue.Resistance-reducing yield should be all 60% or more.In view of glue dosage is relatively fewer, can prepare in advance at the scene.According to total glueLiquid dosage prepares corresponding glue tank quantity, and for convenience's sake, the viscosity of each tank can be a fixed value, when construction notSame viscosity requirement, can be controlled by the bottom gate size that scene adjusts each tank in real time.But it has to guarantee every kindThe glue of viscosity is supplied enough, and therefore, the glue tank of different viscositys can have different quantity.
7. perforation and lower bridge plug joint are constructed
Coiled tubing perforation under first segment, later cable pumping perforation and lower bridge plug.The general hole the 10-16/m of shot density,The general 1-1.5m of single cluster perforating length, the general 9.5mm or more in aperture.
8. low-kappa number operation
It is injected using conventional dilute hydrochloric acid or rare earth acid, dosage is generally 10-20m3, discharge capacity is generally 1-1.5m3/Min, acid inject after be increased to 4-6m3/min for sour discharge capacity, but after waiting acid arrival perforating site, discharge capacity is again decreased to2m3/min or so increases sour antihypertensive effect to increase the time of contact of acid with borehole.After entering borehole Deng the 50% of acid, then willDischarge capacity is increased to 4-6m3/min, to increase the uniform rupture and extension in more shower holes crack.
9. glue seam or low-viscosity slippery water take the high construction of sand control seam
Such as high angle intrinsic fracture agensis in target zone, 20-30m can be taken3High viscosity (50-60mPa.s) glue is madeSeam height is extended to estimated height by seam；But if high angle intrinsic fracture is developed, either unfilled seam or filling seam, dayRight fracture surface is all the plane of weakness on mechanics, is easy to be pressed off, once press off, then stitch it is high it is out of control after, be just difficult to shape in the horizontal directionAt complex fracture.At this time injection early period 20-30m still should be carried out with low-viscosity (1-2mPa.s) slippery water3Afterwards, 4. discharge capacity takes stepThe 50% of determining highest discharge capacity carries extremely-low density (the apparent density 1.05g/cm of partial size 140-230 mesh3) powder pottery proppant,Construct sand liquor ratio 3-8%, step sand liquor ratio amplification 3%, powder pottery dosage 2-4m3, effective to be carried out in the longitudinal direction to high angle fratureIt blocks.Can live real-time judge, if pressure is under the premise of other parameters are constant, stress becomes steady or slightly from downward trendTrend is raised, then judges that the bridge blinding effect of proppant has occurred at the tip of crack or more, it is no even if the injection of proppant can be stoppedThen, injection is maintained always, or properly increases construction sand liquor ratio.
10. the main seam construction of low-viscosity slippery water
In seam up to after being expected to require, using low-viscosity instead (is still 2mPa.s) slippery water, dosage is about the 20- of total liquid measure30%.Results of fracture simulation is as a result, it was confirmed that rate of crack propagation is most fast before the 20-30% for total liquid measure of constructing, at this point, the geometry in crackSize basically reaches 70% or more of final Fracture geometric size, and extension speed later is greatly lowered.The stage is to makeThe critical period of seam, using the combination of low-viscosity and low discharge capacity (take design highest discharge capacity 30%), such net pressure is promotedSpeed is slow, and various small scale Fracture Systems can be made to have the sufficient time to go to link up and extend.Even if net pressure is low, as long as injectionDischarge capacity is higher than the total imbibition discharge capacity in various small minute yardstick cracks, and major fracture can still obtain more adequately extending.Final discharge capacity withViscosity and integrated mode will take into account the balance sufficiently linked up and extend small minute yardstick crack and construction efficiency.It is apparent that viscosity and rowThe product of amount is smaller, and small minute yardstick crack is linked up and extends more, but the construction time can be longer.Conversely, small minute yardstick crackWhat is generated is fewer, but the construction time can be shorter.
The injection of 1 zero 1 variable elements and plus sand construction
After adding sand to start, the ramp type injecting program of stepless variable element is taken.In other words, fracturing fluid viscosity, injection rowAmount and construction sand liquor ratio and four parameters such as sand model (slug formula or continous way) is added to change at any time, especially it is above-mentioned first threeA parameter is increased at any time.Purpose is the net pressure being continuously increased in various scale cracks, continues to increase the several of cracks at different levelsWhat size, and optimize the parameters such as proppant injection way and partial size, sand liquor ratio, maximize the packing density in cracks at different levels.
Slippery water viscosity increases to 12mPa.s from 2mPa.s stepless, as step can carry out 6 using 2mPa.s as amplificationThe injection in a stage, glue viscosity increase to 50mPa.s from 20mPa.s stepless, as step can using 5mPa.s as amplification, intoThe injection in 7 stages of row.After slippery water injection, the injection of glue is then carried out.
Discharge capacity is stepped up by unified requirement, since slippery water, is terminated until glue injects, be should be at being promoted alwaysStage.In the glue stage, the promotion speed of discharge capacity can suitably be accelerated, to realize construction later period crack net pressures at different levels fasterSpeed is promoted.
Sand is added to execute since slippery water injection.Totally two kinds of partial sizes, the proppant first is that 70-140 mesh powder is made pottery, accounting 40-50%, the proppant second is that 40-70 mesh powder is made pottery, accounting 50-60%.First plus 70-140 purpose, then plus the proppant of 40-70 mesh.
For the construction sand liquor ratio of 70-140 mesh proppant from 3% starting, sand liquor ratio amplification is 3%, and most takasago liquor ratio is 15%.If the well head pressure rate of climb is fast, such as larger than 0.5MPa/min should then slow down the upward strain speed of sand liquor ratio, or injection without supportOtherwise the slug (generally with the 110-130% of hole volume) of agent can properly increase construction sand liquor ratio, to mention to the maximum extentThe proppant degree of filling in high cracks at different levels.Until the proppant in the stage adds.
Similarly, the construction sand liquor ratio of 40-70 mesh proppant is from 10% starting, and sand liquor ratio amplification is 2%, most takasago liquor ratioIt is 18%.It is identical that others require the injection with above-mentioned 70-140 mesh proppant to require.It is not both using live flow container injection, noWith the mixed liquor of viscosity, to reach the viscosity range of design requirement, the opening degree of live flow container bottom gate will be adjusted in real time.
Here key is discharge capacity, the promotion speed of viscosity, and what is mentioned is too slow, and the net pressure rate of climb is slow, small minute yardstickFracture extension fills well, but large scale fracture extension with fill insufficient.Conversely, the net pressure rate of climb is too fast, small micro- rulerDegree crack be difficult to sufficiently extend and effectively support, but large scale fracture extension with fill more abundant.And yield simulation after pressingAs a result, it was confirmed that large scale crack influences greatly initial production after pressure, small minute yardstick crack influences production decline big.Therefore, it answersThere is an optimal equalization point, both can guarantee initial stage higher yield, stable yields effect is again relatively preferable after pressure.In addition, plus sand programDesign is also to match the laying form of proppant to the maximum extent with the form of seam using sand liquor ratio mode is increased continuously.But centre can add the slug without proppant, to prevent the risk of sand plug.
1 zero 2 replace operation
By the 110-130% design of this section of hole volume.Half of the hole volume started should be full-bodied glue (viscosity50mPa.s), to prevent the sand setting effect of horizontal wellbore.Use midium-viscosity (viscosity 6mPa.s) and low-viscosity instead laterThe mixed liquor of (2mPa.s) is replaced, the injection until completing all displacement fluids.
1 zero 3 other sections of pressing crack construction, repeat step 7.~step 102, until completing all injection task.
The links such as 1 zero 4 other brill plugs, the row of returning, test and production are executed referring to old process.
The present invention has following technical characterstic and excellent results: the present invention has rational design, feasibility is high, glutinous by fracturing fluidDegree injects discharge capacity and construction sand liquor ratio and adds four parameters such as sand model (slug formula or continous ways), makes the filling in cracks at different levelsDegree maximizes, and guarantees initial stage higher yield to a certain extent, while can stablize stable yields effect after pressure again.The present invention mainly answersFor in deep layer shale gas well fracturing.The present invention changes fracturing fluid viscosity, injection discharge capacity and construction sand at any time according to the actual situationLiquor ratio and add four parameters such as sand model (slug formula or continous way), so that it is continuously increased the net pressure in various scale cracks,Continue to increase the geometric dimension in cracks at different levels, and optimize the parameters such as proppant injection way and partial size, sand liquor ratio, makes cracks at different levelsPacking density maximize, thus guarantee initial production it is higher simultaneously, stable yields effect after relatively good pressure is obtained, in deep layerIt has broad application prospects in shale gas well fracturing.
Embodiment:
Certain well, well vertical depth 3789m, depth measurement 4962m, horizontal segment length 1300m.Provided method carries out through the inventionOptimization design, step and result are as follows:
(1) shale key Cook method is thought, the high-quality shale development of the well, Static State Index is good, and brittleness is medium partiallyOn, part interval develops high angle intrinsic fracture.
(2) determine that double dessert areas (comprehensive dessert > 0.5) of geology dessert and engineering dessert are used as perforation cluster position.
(3) numerical simulation is carried out using ECLIPSE software, modeling scheme design is carried out using orthogonal scheme, is obtained optimalThe fracturing parameter of long-term yield is as follows after pressure: 18 sections of pressure break, optimal seam spacing 16-28m, fracture half-length 260-300m, water conservancy diversion energyPower is 30-55mDm, takes W type cloth slit die formula.
(4) crack propagation numerical simulation of optimum is carried out using MEYER software, it is as a result as follows: 15~16m of discharge capacity3/Min, single hop fracturing fluid dosage 1800-2100m3, single hop support dosage 65m3-80m3, proppant partial size be -140 mesh of 70 mesh and40-70 mesh, slippery water viscosity 2-12mPa.s, glue viscosity 20-50mPa.s, the wherein 35-45% of the total liquid measure of glue Zhan.
(5) slippery water of 6 kinds of viscositys is configured, viscosity is followed successively by 2,4,6,8,10,12mPa.s, resistance-reducing yield > 65%.
(6) glue of 7 kinds of viscositys is configured, viscosity is followed successively by 20,25,30,35,40,45,50mPa.s, resistance-reducing yield > 60%.
(7) perforation and lower bridge plug joint are constructed, 16 holes of shot density/m, single cluster perforating length 1.5m, aperture 12mm.
(8) pretreatment uses 10m3 dilute hydrochloric acid, and acid filling discharge capacity 1m3/min injects 40m using the discharge capacity of 6m3/min later3Discharge capacity is reduced to 2m3/min to inject 5m by slippery water3Slippery water, then discharge capacity is increased into 6m3/min injection 5m3Slippery water.
The development of (9) the 8th, 13,16 sections of high angle intrinsic fractures, first injects 2mPa.s low-viscosity slippery water 20m3, after with8m3The discharge capacity of/min injects the extremely-low density powder pottery proppant 2-4m3 of partial size 140-230 mesh according to the sand liquor ratio of 3-6-8%,The total injection 250-300m of this stage slippery water3.The glue of viscosity 50mPas is injected in remaining section of high angle intrinsic fracture agensisLiquid 200m3As prepad fluid.
(10) according to 8m3The slippery water 400m of the discharge capacity injection viscosity 2mPas of/min3。
(11) it is implanted sequentially the slippery water that viscosity is 2,4,6,8,10,12mPa.s, every kind of viscosity slippery water discharge capacity is followed successively by8、9、10、11、12、13m3/ min, 70-140 mesh proppant sand ratio are followed successively by 3,6,9,12,14,15%, every kind of viscosity liquid noteEntering amount is 100m3, the total sand amount of 70-140 mesh proppant is 30m3.And then be implanted sequentially viscosity be 20,25,30,35,40,45, the glue of 50mPa.s, every kind of viscosity glue discharge capacity are followed successively by 13,14,15,16,16,16,16m3The support of/min, 40-70 meshAgent sand ratio is followed successively by 10,12,14,16,16,18,18%, and every kind of viscosity liquid injection rate is 90m3, 40-70 mesh proppant is totalSand amount is 40m3。
(12) 25m is used3Viscosity is the glue and 30m of 50mPa.s3The mixed liquor that viscosity is 6mPa.s and 2mPa.s carries outIt replaces.After pressure break, the row of returning, production test are executed according to old process and puts into serial production work.
Implement through the invention, 18.5 × 104m3 of open-flow capacity after the well pressure, gas production improves 1 compared with offset well yield~2 times.