CN109958429A - A method of judging shale gas adsorbed gas output - Google Patents
A method of judging shale gas adsorbed gas output Download PDFInfo
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- CN109958429A CN109958429A CN201711391306.4A CN201711391306A CN109958429A CN 109958429 A CN109958429 A CN 109958429A CN 201711391306 A CN201711391306 A CN 201711391306A CN 109958429 A CN109958429 A CN 109958429A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
Abstract
The present invention provides a kind of methods for judging shale gas adsorbed gas output, belong to shale gas exploration and development field.This method or is analyzed the form of shale gas well creation data double logarithmic curve by restoring the form of double logarithmic curve to shale gas well pressure, judge in production process whether the output number of adsorbed gas, the period of output and output.It not only can restore test curve using shut-in pressure using the method for the present invention and relatively accurately judge the output for whether having adsorbed gas in production process, and the period of output, and whether creation data double logarithmic curve capable of being applied in the case where lacking well testing test data to judge adsorbed gas output, and can be visually observed that by well-test curve adsorbed gas whether output, the period of output, output number etc..
Description
Technical field
The invention belongs to shale gas exploration and development fields, and in particular to a method of judge shale gas adsorbed gas output.
Background technique
From the point of view of global energy Development Strategy, the development of unconventional gas reservoir is just changing the energy pattern in the world and is becoming complete
The focus of ball exploitation.It is predicted that shale gas total resources is about 456 × 10 in world wide12m3, account for about Unconventional gas (coal
Layer gas, compact sandstone gas, shale gas) total resources 50%.Shale gas is mainly present in ground with free state or adsorbed state
Under, free gas is mainly distributed in fracture pore and matrix pores；Adsorbed gas is mainly distributed on the interior table of matrix system micropore
Face.Since free gas and adsorbed gas exist simultaneously, flowing in shale reservoir has a variety of flow characteristics: from macroscopically, by
Microcrack present in the man-made fracture and shale formation that hydraulic fracturing generates is flow of air channel of dissociating in shale formation,
Darcy Flow is remained in the crack of these large scales.From microcosmic, since the porosity of shale generally all compares
It is small, much be in nanometer scale, Darcy Flow there are a possibility that very little, but with distinctive diffusion into the surface, molecule diffusion,
The flowing of Michel Knuysen diffusion way progress gas；After shale gas reservoir completes wellbore construction, the pressure decline on stratum will lead to,
Original adsorption equilibrium is destroyed, desorption phenomenon is generated.Therefore shale gas has unique desorption and adsorpting characteristic,
There are multistage, the multiple dimensioned seepage characteristic for being clearly distinguishable from conventional gas, the micro flows such as desorption, diffusion especially in terms of seepage flow
What the adsorbed gas that movable property goes out occupied more part and parcel and Accurate Prediction shale gas production capacity in shale gas yield must can not
Few condition.Adsorbed gas is all adsorbed on stromal surface, and only desorption comes out ability output, it is therefore desirable to which foundation has efficacious prescriptions
Method judges when desorption comes out adsorbed gas, i.e., when output adsorbed gas.
For predicting adsorbed gas output technology in current existing shale gas adsorbed gas determination techniques, well production process, with
And shale gas well deliverability calculation method etc. has carried out extensive investigation retrieval, wherein retrieving 12 related patents.It is public at present
The patent opened has plenty of based on laboratory facilities, measures using instrument to shale core, so that it is determined that adsorbing in shale formation
The content of gas, measure shale adsorption curve, such as based on shale gas adsorbed gas content is analyzed system (application number:
CN201420587194.5), shale gas adsorption-desorption simple experimental device (application number: CN201520847718.4) etc., but it
Cannot for production in shale gas well judge whether there is adsorbed gas generate and generate period.Have plenty of and establishes various pages
Rock gas Production Forecast Models, production decline method etc. carry out production forecast, evaluate single well productivity, are such as based on early yield data
Predict the method (CN710436233.X) of shale gas well recoverable reserves, shale gas reservoir single well productivity calculation method
(CN201610559081.8), a kind of oil/gas well Production Decline Analysis method and system (CN201410638125.7), a kind of page
Rock air water horizontal well initial productivity prediction technique (CN201510124601.8), a kind of deliverability testing method
(CN201410784754.0), the logging prediction method (CN201710137973.3) of shale gas horizontal well single well productivity.This six
Item patent does not all account for the yield of adsorbed gas in gas well yield, has no and is related to the part of the content of present invention.Other 4 patents
It is to disclose the prediction technique of shale gas well deliverability, shale gas well deliverability method of evaluation and forecast (CN201410536314.3) passes through
Shale gas horizontal well fracturing production formula is determined to the fitting of creation data, while considering desorption, diffusion feature, establishes page
Rock gas evaluating production capacity method；A kind of shale gas well deliverability measuring method (CN201410112840.7) establishes pair of consideration adsorbed gas
The compound shale material balance equation for gas reservoir in area establishes a kind of fast and accurately shale gas well deliverability calculation method；A kind of shale gas
Horizontal well multistage productivity of fractured prediction technique and device (CN201510454838.2) are hidden using the shale gas reservoir after fracturing reform
Initial parameter establishes Fluid Control Equation in matrix and Fracture System, obtains fracture pressure distribution, obtains page using deliverability equation
Rock gas production capacity.It is all to predict adsorbed gas yield using langmuir adsorption equation when calculating absorption tolerance in this 3 existing patents,
It is not according to actual production curve to determine whether generating adsorbed gas.A kind of shale gas Production Decline Analysis method
(CN2014108-52718.3) quality of free gas flowed out in crack is calculated using diffusion coefficient, using gas pressure and
Shale air tightness determines the quality of desorption gas, determines gas well yield production decline law according to formation parameter, determines the final well of gas well
Mouth yield, can only calculate the content of adsorbed gas in shale formation, can not judge to give birth in real time according to actual production curve
It produces and when generates adsorbed gas in the process.Therefore there is no the summary of the invention that the present invention illustrates for existing patented technology.
In non-patent literature, it retrieved 7 pertinent literatures.Wherein, " multifactor shale absorption tolerance calculates and shadow
Ring factorial effect analysis " adsorption isotherm experiment is based on as a result, establishing consideration total content of organic carbon, kerogen maturity, depth three
The absorption tolerance computation model of factor." the shale adsorbed gas content New calculating method based on adsorption isotherm experiment " is calculated not
Under the influence of considering temperature, pressure change adsorbs the changing rule of getting up to shale." consider that the shale of formation temperature and pressure is inhaled
Attached Gas content novel model of calculating " is based on utilizing langmuir model, according to temperature, pressure, TOC value, RO value and adsorbed gas content
Between relationship, establish consider formation temperature, 4 pressure, organic carbon content and maturity factors shale adsorbed gas content meter
Calculate new model." acoustic attenuation characterizes shale adsorbed gas _ free Gas content experimental study " carries out isothermal adsorption-sound wave to shale
Translocation experiment, specifies influence of the adsorbed gas to acoustic attenuation, proposes dissociate in acoustic attenuation characterization shale tolerance and adsorbed gas
The method of amount.It is existing that " the negative adsorption phenomena pre-test of shale isothermal adsorption Gas content " systematically analyzes the negative absorption of shale adsorption isothermal curve
As the reason of, and propose correction suggestion, mentioned for the Accurate Determining and objectively evaluating for shale gas stock number of shale adsorbed gas content
Foundation is supplied." shale gas adsorbs collective model and its application to shale adsorption isothermal curve under different temperatures " carries out a series of meters
Shale gas absorption collective model has been obtained, adsorption isothermal curve under different temperatures and pressure condition is calculated." with isothermal adsorption side
Method correctly evaluates mud shale adsorbed gas content " have studied influence of the temperature and pressure comprehensive function to mud shale adsorpting characteristic.It is non-
Patent document is all based on shale adsorption isotherm experiment or isothermal adsorption formula, calculates adsorbed gas content in shale formation, not
Can judge shale gas well in production process whether the period of output adsorbed gas and adsorbed gas output.
Summary of the invention
It is an object of the invention to solve above-mentioned problem existing in the prior art, a kind of judgement shale gas adsorbed gas is provided
The method of output can not only press extensive test curve to judge whether to produce adsorbed gas in production process using closing well, and
And whether capable of judging that adsorbed gas generates using creation data double logarithmic curve in the case where lacking well testing test data, and
Can be visually observed that by well-test curve adsorbed gas whether output, the period of output, output number etc..
The present invention is achieved by the following technical solutions:
A method of judging that shale gas adsorbed gas output, the method are bent by restoring double-log to shale gas well pressure
The form of line, or the form of shale gas well creation data double logarithmic curve is analyzed, judge whether produce in production process
The number of adsorbed gas, the period of output and output is gone out.
The described method includes:
(1) shale gas well test data is collected；
(2) according to shale gas well test data plotting shale gas well double logarithmic curve；
(3) shale gas well double logarithmic curve is analyzed, whether occurs recessed form on judgment curves, if it is not, then
Judgement does not have output adsorbed gas, if it is, determining output adsorbed gas, and is obtained according to the position of recessed form appearance, number
The period of adsorbed gas output and the number of output.
The step (1) is achieved in that
If carrying out shut-in pressure in process of production restores test, the shale gas well test data collected is pressure
Restore test data；
If restoring test without carrying out shut-in pressure in process of production, the shale gas well test data collected is made a living
Produce data.
The pressure recovery test data include pressure and time；
The creation data includes the well head pressure and well head yield of daily well head measurement.
The step (2) is achieved in that
If carrying out shut-in pressure in process of production restores test, according to pressure recovery test number in coordinate diagram
Restore double logarithmic curve according to shale gas well pressure is made, the abscissa of the coordinate diagram is the time, and ordinate is that pressure and pressure are led
Number；In two curves, a curve changed over time for pressure, another curve changed over time for pressure derivative；
If restoring test without carrying out shut-in pressure in process of production, drawn in coordinate diagram according to creation data
Creation data double logarithmic curve, the abscissa of the coordinate diagram are the material balance time, and ordinate is flow Regularization pressure and stream
Gauge integralization pressure derivative；In two curves, one is flow Regularization pressure with the curve of material balance time change, another
Item is curve of the flow Regularization pressure derivative with material balance time change；The material balance time are as follows: cumulative production/day
Yield, the Regularization pressure are as follows: (original formation pressure-well head pressure)/daily output.
If the creation data double logarithmic curve drawn out uses material balance in a jumble without rule in the step (2)
It is double right that time draws as abscissa, flow Regularization pressure integral and flow Regularization pressure integral derivative as ordinate
Number curve, in two curves, a curve integrated for flow Regularization pressure with material balance time change, another is stream
Gauge integralization pressure integral derivative with material balance time change curve；If the double logarithmic curve obtained at this time is still mixed and disorderly
Without rule, then abnormal point is removed manually, then double logarithmic curve is smoothed with interpretation software.
Period and the output of adsorbed gas output are obtained in the step (3) according to the position of recessed form appearance, number
Number be achieved in that
The abscissa corresponding period for the position that the recessed form occurs is the period of adsorbed gas output；
The number that the recessed form occurs is the number of adsorbed gas output.
Compared with prior art, the beneficial effects of the present invention are: the present invention not only can restore test using shut-in pressure
Curve relatively accurately judges the period of the output for whether having adsorbed gas in production process and output, and can be
Lack in the case where well testing test data using creation data double logarithmic curve come whether judging adsorbed gas output, and can pass through
Well-test curve be visually observed that adsorbed gas whether output, the period of output, output number etc., therefore the scope of application greatly increases
?.The case where adsorbed gas output in production process can be observed directly using well-test curve using the present invention, further recognize
The multiple dimensioned flowing law of shale gas reservoir analyzes shale gas well production status changing rule, to evaluation shale gas well deliverability and warp
Ji benefit plays a significant role.It is applicable present invention can apply to any production phase in shale gas well normal productive process
In the gas well for thering is closing well to press extensive test data, it can also be applied to the gas well of no test data, have broad application prospects.
Detailed description of the invention
Fig. 1 shale gas formation gas Storage mechanism
Fig. 2 shale gas formation gas molecule migration mechanism schematic diagram
Fig. 3 diplopore formation flow schematic diagram
Fig. 4 shale gas considers absorption, diverging flow schematic diagram
Fig. 5 double porosity model well testing double-log pressure and derivative curve
Fig. 6 adsorption and diffusion model well-test curve
Creation data pressure, the production rate curve of Fig. 7 embodiment 1
The Regularization pressure double logarithmic curve of Fig. 8 embodiment 1
The Regularization pressure of Fig. 9 embodiment 1 integrates double logarithmic curve
Creation data pressure, the production rate curve of Figure 10 embodiment 2
The Regularization pressure double logarithmic curve of Figure 11 embodiment 2
The Regularization pressure of Figure 12 embodiment 2 integrates double logarithmic curve
The step block diagram of Figure 13 the method for the present invention.
Specific embodiment
Present invention is further described in detail with reference to the accompanying drawing:
The present invention provides a kind of methods for judging shale gas desorption gas and whether generating, and derive shale micro flow motivation
Reason, establishes the dual media flow model that shale adsorbed gas is diffused into crack from nanoaperture, extensive by shale gas well pressure
Multiple double logarithmic curve form or creation data double logarithmic curve form, analyze double logarithmic curve form, judge to produce
The period of adsorbed gas, output, output number etc. whether are produced in the process.
The present invention is studied according to shale microscopic percolation mechanism, and adsorbed gas is present in nanoscale micro-pore, these gas
Body is to be entered in big microcrack or other flow channels in the form of desorption, diffusion etc., and then flow into well, therefore, works as suction
After attached gas participates in flowing, there are two types of different pore medias in stratum, and there is two different types of flow, in pressure recovery
Display is similar to double-porosity system flow characteristics on double logarithmic curve, it is possible thereby to judge whether there is adsorbed gas output.This
Invention is to judge whether have in output gas by the double logarithmic curve actual response of the formation pressure data drafting of closing well test
Adsorbed gas exists, therefore judging result is more true and reliable, can determine whether when generate adsorbed gas in production process.This method mesh
It is preceding domestic and international there is not yet related technology reports.
Detailed process of the invention is as follows:
(1) shale gas formation gas flow mechanism and feature description
The flowing of shale gas reservoir is usually two kinds of migration machines of the both macro and micros such as percolation in porous medium, desorption-diffusion
System coupling.
It is dispersed in shale gas stratum small hole (being also likely to be present intrinsic fracture), gas is divided in the form of free gas
Cloth forms hole (intrinsic fracture space) pressure in hole (including intrinsic fracture) space；In addition in interstitial space also
It is dispersed with the kerogen of not yet mature release free gas one's share of expenses for a joint undertaking form, gas molecule is adsorbed on kerogenic by the mechanism of absorption
Surface, this kind of gas are exactly adsorbed gas.Fig. 1 is the occurrence form of the gas in shale gas stratum.
Free gas is stored in interstitial space, and gas molecule is filled with interstitial space, causes the presence of pore pressure.When
The porosity communication of some hole and surrounding space, and there are when barometric gradient, free gas will be in the effect of barometric gradient
Lower carry out percolation in porous medium.Its seepage flow characteristics substantially follows the citation form of Darcy's law, but since pore scale is smaller,
Seepage flow in shale formation is slightly different.
Adsorbed gas relies primarily on pore pressure and is adsorbed on kerogenic surface.Diffusion is also gas fortune in shale gas stratum
The important mechanism moved.In shale gas interstitial space, there is unmature kerogens.In these kerogens, deposit
It stores up and is dissolved in gas molecule therein.The free gas molecule that the concentration of gas molecule in kerogen is greater than interstitial space is dense
Degree, also greater than the adsorbed gas molecular concentration of cheese root surface.So gas molecule inside kerogen to Gas Molecular Density compared with
Low diffusion into the surface.
Fig. 2 is the schematic diagram of the shale gas gas flowing of ideal two kinds of flow mechanisms coupling.Intermediate interstitial space is
The medium of the main thoroughfare that gas molecule is migrated in shale gas stratum, naturally also free gas storage；It all represents up and down in list
The kerogen contained in the shale pore volume of position, the interface of two parts are then the medium of adsorbed gas storage.Interstitial space with
The pressure oscillation that adjacent interstitial space occurs in gas production process forms barometric gradient, flows into from the adjacent space at remote well end
Gas molecule is flowed out to the interstitial space at nearly well end.Due to the flowing of free gas, interstitial space gas molecule quantity is caused
Variation, to cause the pressure change in interstitial space, at this moment, in change of the adsorbed gas due to experiencing pressure of cheese root surface
Change, it then follows the process of absorption or desorption occurs for Lang Moer isothermal adsorption rule；And kerogen adsorption gas concentration
Variation will cause the variation inside kerogen with the gas concentration difference on surface again, so that the gas molecule inside kerogen is again
New adsorbed gas distribution can be formed to kerogen diffusion into the surface.So, it is believed that interstitial space is both memory space, and
The channel of gas molecule migration, and kerogen, whether surface or inside, are all the memory spaces of gas molecule, i.e. gas
Molecule does not pass through the basic body of cheese and migrates to other adjacent pores spaces.
In conclusion shale gas is flowed into the process of pit shaft by stratum are as follows: with the decline of strata pressure, be attracted to cheese
Adsorbed gas in root is desorbed out, and diffuses to interstitial space, and the gas in interstitial space reaches pit shaft by seepage effect.This
The entire flow process of sample is made of micro flow (absorption, diffusion) and two kinds of flowings of seepage flow, is equivalent in two kinds of pore medias
Flowing, if adsorbed gas also produces, micro flow is also assisted in the flowing of gas, should table on well-test curve
Reveal the flow characteristics of double-porosity system.
(2) mathematical model is established after shale gas well considers absorption, diffusion
In shale gas well production process, adsorbed gas and free gas simultaneously output when, the flowing in stratum is similar to dual
The flow characteristics on medium stratum, i.e. adsorbed gas are from desorption, diverging flow and free gas of the kerogen into interstitial space from hole
Gap space is equivalent to flowing of the flowing and crack of matrix in double porosity model to crack to pit shaft, such as schemes to the seepage flow of pit shaft
3, Fig. 4 show the flow characteristics on diplopore stratum and shale gas considers the flow characteristics contrast schematic diagram after absorption, diffusion.From figure
3, Fig. 4 can be seen that the seepage flow of absorption, the flowing of diffusion and interstitial space, similar to diplopore mesostroma, two kinds of flowings in crack,
Double porosity model flow characteristics can be shown on the well-test curve of shale gas well.Therefore storage can be equally defined to hold than ω and channelling system
Number λ establishes shale gas and considers the mathematical model after absorption, diffusion.
Gas in shale gas is the mixed gas based on methane, the equation after considering seepage flow and diffusion are as follows:
Wherein, V is the concentration of mixed gas in shale；P is the pressure of gas in the earth formation；T be gas in the earth formation
Temperature；μ is gas viscosity；Z is the deviation factor for gas in actual gas state equation；K is in-place permeability；When t is production
Between, subscript sc indicates the physical quantity under standard state.Gas concentration in shale can be provided by following relationship:
Wherein, D is gas diffusivity in shale；R is gas diffusion outer radius in shale；VEFor gas under equilibrium state
Concentration；VicGas concentration when for t=0.After considering pressure-sensitive and gas PVT, normal pressure is defined:
Define dimensionless variable normal pressure:
Nondimensional time:
Elastic storativity ratio:
Interporosity flow coefficient:
Dimensionless distance:
Wherein, subscript i indicates the physical quantity under original state, and φ is porosity, qscFor the flow under standard state, BgFor
Gas volume factor, CgFor isothermal compressibility, τ is the adsorption time in shale gas:
α is that coefficient is held in comprehensive storage:
L is fracture half-length's summation:
After carrying out nondimensionalization, equation becomes:
In Laplacian space, the expression-form of equation are as follows:
Wherein s is Laplace variable.
If, according to Langmuir equation, the adsoption equation of shale gas is write as under standard pressure conditions:
Wherein, mLFor Langmuir adsorption criteria pressure, VLFor Langmuir adsorption criteria pressure, micWhen for t=0
Langmuir adsorptive pressure.It is assumed that following formula is constant:
Then formula (16) can be write as:
VED=-α mD (18)
Then, formula (15) can be expressed as:
Wherein:
Substituting the above in equation (12) can be obtained:
Wherein, coefficient function are as follows:
(3) difference of adsorption and diffusion model and double porosity model
But adsorption and diffusion model is not fully identical as double porosity model, is essentially different on flowing law, this
The well-test curve form for also resulting in well-test curve feature and double porosity model caused by adsorbed gas output is different.
1, the definition of elastic storativity ratio and interporosity flow coefficient is different
In double porosity model, matrix is as reservoir space, and crack is as flow channel, elastic storativity ratio definition in double porosity model
For in unit volume rock, one atmospheric pressure of every change, crevice volume changes the ratio with total volume variation, expression formula
Are as follows:
The expression formula of interporosity flow coefficient λ are as follows:
ω and λ in double porosity model is related with the porosity in matrix and crack, the compressed coefficient, permeability, form factor, it
It describes the gas in matrix and flow to crack, then the flow process by flow in fracture into pit shaft, have rated the gas in matrix
Body flow to the ability in crack.
And adsorption time, desorption amount of ω and λ and adsorbed gas in previously defined adsorption and diffusion model etc. is related, it
The flowing of description is the adsorbed gas amount that desorption comes out from matrix, is diffused into microcrack, then flow to the process of pit shaft, whole
A flow mechanism is different from the flow mechanism of double porosity model.
2, the differential equation of two kinds of models is different
Shown in the Adsorption Model differential equation such as formula (21), and the differential equation of double porosity model is formula (25).
Adsorption Model:
Double porosity model:
M in double porosity modelfDIt is substantially identical from seeing in form for the differential equation for the normal pressure in Fracture System,
But the definition of coefficient function f (s) therein is entirely different.
The coefficient function of Adsorption Model:
The coefficient function of double porosity model:
The coefficient of double porosity model is only related with ω and λ, so model is to describe the flowing of matrix to crack, crack to pit shaft
Process, and the coefficient of Adsorption Model is in addition to related with ω and λ, it is also related with α, it describes adsorbed gas and carries out desorption, diffusion
Process, so the flow mechanism of two kinds of differential equations is different, the physical significance of expression is different.
(4) shale gas considers absorption, diffusion model well-test curve feature
As described above, two kinds of streams the seepage flow of absorption, the flowing of diffusion and interstitial space, with diplopore mesostroma, crack
It is dynamic to regard similar pattern of flow as, therefore can also show to be similar to double porosity model well testing song on the well-test curve of shale gas well
Line morphology feature can see the recessed curved shape of similar double porosity model on the well-test curve for considering absorption, diffusion model
State.
But the flow mechanism of adsorption and diffusion model is again different with double porosity model, and in the flowing of double porosity model, base
Gas in matter is all flow in crack, then by flow in fracture into pit shaft, and the flowing of matrix to crack is continuously, whole
Occupy very big ratio in a flow process, recessed on double porosity model well-test curve has meant that gas from a kind of pore media
Flowing (as shown in Figure 5) into another pore media, therefore recessed bigger on curve, and can only have one it is recessed
Curvilinear characteristic；And the flowing in adsorption and diffusion model, then it is the adsorbed gas desorption when meeting desorption sub conditione, in matrix,
It is diffused into crack, becomes free gas, then by flow in fracture into pit shaft, desorption, diffusion process are discontinuous, Mei Dangda
When to desorption, diffusion conditions, this flowing will occur, when the conditions are not met, desorption, diverging flow can stop again,
And desorption, the gas volume of diffusion are smaller each time, although thus on well-test curve and showing as recessed form (such as
Shown in Fig. 6), but recessed figure is smaller, and will appear multiple recessed form on curve, such case is in double porosity model
Be not on curve.Therefore, adsorbed gas output can be judged whether there is by this tracing pattern feature, can also distinguished
Diplopore stratigraphic model and adsorbed gas input output model out
(5) using well-test curve judge shale gas adsorbed gas whether the method for output
According to the analysis in (four), shale gas considers the well-test curve feature of absorption, diffusion model, with other any models
Well-test curve form be different from, therefore can use the unique well-test curve form of absorption, diffusion model, to judge page
Whether there is the flowing of absorption, diffusion to generate in the flowing law of rock gas well, thus judges whether there is adsorbed gas output in output gas.
As shown in figure 13, judgment method of the present invention is as follows:
(1) shale gas well test data is collected first.If carrying out shut-in pressure in process of production restores test,
It can be judged using the extensive test data (i.e. pressure recovery test data) of pressure；If without carrying out closing well survey in production process
Examination can be judged using creation data (i.e. the pressure and yield data of well head).It is not recommended that the stratum before application is gone into operation is surveyed
Examination data is judged, because not entering into normal production, therefore can not represent normal without carrying out fracturing reform at this time
Production process.Pressure recovery test data are packets in the data readback to computer tested with the pressure gauge under lower going-into-well
Time, pressure, temperature etc. are included, what the present invention applied is the data of time and pressure, and playback of data format is as shown in table 1.
Table 1
(2) shale gas well double logarithmic curve is drawn.If application presses extensive test data to be judged, well test analysis can be used
Software makes well testing double logarithmic curve, and the abscissa of curve is the time, and ordinate is the derivative of pressure and pressure.Double logarithmic curve
On have two curves, above be line that pressure changes over time, below be line that pressure derivative changes over time, it is general go out
Now recessed feature is all on differential of pressure curve, therefore while being judged sees the variation of following pressure derivative line.
Creation data data and shut-in pressure restore that data are distinguishing, creation data be include daily well head measurement well head pressure with
Well head yield needs application traffic Regularization pressure method to carry out creation data if judged with creation data data
Processing can apply creation data interpretation software (such as Topaze software) in actual use, draw log-log curve, double at this time
The abscissa of logarithmic curve is material balance time (i.e. cumulative production/daily output), and ordinate is flow Regularization pressure and stream
The derivative of gauge integralization pressure.The expression formula of Regularization pressure is: (original formation pressure-well head pressure)/daily output, i.e.,Although the transverse and longitudinal coordinate for the curve that two kinds of test datas are made is different, the morphological feature of double logarithmic curve
Be it is identical, can using this method judge adsorbed gas output whether.
(3) double logarithmic curve is analyzed, as shown in fig. 6, shale gas well if there is adsorbed gas output, can go out on curve
Now spill state, this recessed different from double porosity model feature, its scale is recessed more much smaller than diplopore curve, Er Qiehui
Occur several recessed forms in entire curve, such case is that can not occur in double porosity model.It is possible thereby to judge
There is the output of adsorbed gas in shale gas production process, and recessed appearance is exactly to desorb the flowing being diffused into crack by adsorbed gas
Caused by.
(4) it is worth noting that, the quality of data often enrolled of creation data data is poor, in daily production process due to
It is influenced by various external or human factor, causes curve also can be relatively more mixed and disorderly, many abnormal points can cover production law table
Reveal and.Therefore when drawing creation data double logarithmic curve, if drawn with Regularization pressure and Regularization pressure derivative,
Curve without rule, can use Regularization pressure integral and Regularization pressure integral derivative to make as ordinate more in a jumble
Figure, can obtain more regular double logarithmic curve.But if curve is still more mixed and disorderly, abnormal point is removed manually, then
Being smoothed with interpretation software to double logarithmic curve can be obtained regular double logarithmic curve.
The embodiment of the method for the present invention is as follows:
Embodiment 1:
Illustrate application of the invention by taking certain external oil field a bite multistage pressure break shale gas horizontal well as an example.The well prime stratum
Pressure is 48.26MPa, and a length of 1219.2m of net horizontal section, pressure break series is 24 grades.The well application creation data is judged, raw
Producing the time is 7056 hours, and the daily output and pressure data are every 24 hours 1 points, totally 295 groups of data.It is drawn using creation data
The daily output of well head, cumulative production change over time curve and pressure time curve, as shown in Figure 7.
Creation data double logarithmic curve is made using Well Testing Software, as Regularization pressure and pressure product have been done in Fig. 8,9 respectively
The double logarithmic curve divided.From the point of view of curve comparison, Fig. 8 shows that Regularization pressure double logarithmic curve form is more clear in the present embodiment
Clear, from well-test curve form, after the well hole storage stage of early stage, gas well liquid loading is substantially at the linear flow stage,
It can tell in linear flow early stage, about when producing 200 hours, 800 hours, there is adsorbed gas output respectively,
Fig. 9 shows the well testing double logarithmic curve drawn using Regularization pressure integral and integral derivative as ordinate, tracing pattern
It is more regular, it equally can recognize that the signal of adsorbed gas output form, output time slightly have error twice.
Embodiment 2:
This example illustrates application of the invention by taking the block a bite multistage pressure break shale gas horizontal well of Fuling as an example.The well is primitively
Stressor layer is 36.9MPa, and a length of 1007m of net horizontal section, pressure break series is 13 grades.The well application creation data is judged, raw
Producing the time is 18600 hours, and the daily output and pressure data are every 24 hours 1 points, totally 776 groups of data.It is drawn using creation data
The daily output of well head processed, cumulative production change over time curve and pressure time curve, as shown in Figure 10.
Creation data double logarithmic curve is made using Well Testing Software, as Regularization pressure and pressure have been done in Figure 11,12 respectively
The double logarithmic curve of integral.From the point of view of curve comparison, it is double right to draw using Regularization pressure and pressure derivative as ordinate
Number curve (Figure 11), curve is disorderly and unsystematic, can not identify the flowing law in production, therefore can not apply.Figure 12 is application rule
The well testing double logarithmic curve that integralization pressure integral and integral derivative are drawn, tracing pattern is relatively clear, from well-test curve form
It sees, the well hole storage stage of early stage can not observe that gas well liquid loading is substantially at the linear flow stage, repeatedly go out in process of production
The notching curve form of existing adsorbed gas output, as shown in mark in Figure 12.It is possible thereby to substantially tell to produce 700 small
When, when 2000 hours, 4000 hours, 7000 hours, there is adsorbed gas output respectively.
After above-described embodiment is implemented achieving the following effects: (1) apply shale gas well liquid loading data, draw double-log examination
Well curve, and compared the double logarithmic curve morphological feature of Regularization pressure and Regularization pressure integral as ordinate when, always
The range and effect of application are tied；(2) the well testing double logarithmic curve drawn for creation data, identifies production process on curve
In Field Characteristics, identify each flow sections, and the curvilinear characteristic of application absorption, diffusion model judges whether shale gas produces
Out and the general output time.
Above-mentioned technical proposal is one embodiment of the present invention, for those skilled in the art, at this
On the basis of disclosure of the invention application method and principle, it is easy to make various types of improvement or deformation, be not limited solely to this
Invent method described in above-mentioned specific embodiment, therefore previously described mode is only preferred, and and do not have limitation
The meaning of property.
Claims (7)
1. a kind of method for judging shale gas adsorbed gas output, it is characterised in that: the method passes through extensive to shale gas well pressure
The form of multiple double logarithmic curve, or the form of shale gas well creation data double logarithmic curve is analyzed, judge to produce
In journey whether the output number of adsorbed gas, the period of output and output.
2. the method for judgement shale gas adsorbed gas output according to claim 1, it is characterised in that: the described method includes:
(1) shale gas well test data is collected；
(2) according to shale gas well test data plotting shale gas well double logarithmic curve；
(3) shale gas well double logarithmic curve is analyzed, whether occurs recessed form on judgment curves, if it is not, then determining
There is no output adsorbed gas, if it is, determining output adsorbed gas, and is adsorbed according to the position of recessed form appearance, number
The period of gas output and the number of output.
3. the method for judgement shale gas adsorbed gas output according to claim 2, it is characterised in that: the step (1) is
It is achieved:
If carrying out shut-in pressure in process of production restores test, the shale gas well test data collected is pressure recovery
Test data；
If restoring test without carrying out shut-in pressure in process of production, the shale gas well test data collected is production number
According to.
4. the method for judgement shale gas adsorbed gas output according to claim 3, it is characterised in that: the pressure recovery is surveyed
Trying data includes pressure and time；
The creation data includes the well head pressure and well head yield of daily well head measurement.
5. the method for judgement shale gas adsorbed gas output according to claim 4, it is characterised in that: the step (2) is
It is achieved:
If carrying out shut-in pressure in process of production restores test, done in coordinate diagram according to pressure recovery test data
Shale gas well pressure restores double logarithmic curve out, and the abscissa of the coordinate diagram is the time, and ordinate is pressure and pressure derivative；Two
In curve, a curve changed over time for pressure, another curve changed over time for pressure derivative；
If restoring test without carrying out shut-in pressure in process of production, is drawn and produced according to creation data in coordinate diagram
Data double logarithmic curve, the abscissa of the coordinate diagram are the material balance time, and ordinate is that flow Regularization pressure and flow are advised
Integralization pressure derivative；In two curves, one is flow Regularization pressure with the curve of material balance time change, and another is
Flow Regularization pressure derivative with material balance time change curve；The material balance time are as follows: cumulative production/daily output
Amount, the flow Regularization pressure are as follows: (original formation pressure-well head pressure)/daily output.
6. the method for judgement shale gas adsorbed gas output according to claim 5, it is characterised in that: in the step (2)
If the creation data double logarithmic curve drawn out without rule, uses the material balance time to advise as abscissa, flow in a jumble
Integralization pressure integral and flow Regularization pressure integral derivative draw double logarithmic curve as ordinate, in two curves, one
Item is curve of the flow Regularization pressure integral with material balance time change, and another is flow Regularization pressure integral derivative
With the curve of material balance time change；If the double logarithmic curve obtained at this time still in a jumble without rule, removes manually
Then abnormal point is smoothed double logarithmic curve with interpretation software.
7. the method for judgement shale gas adsorbed gas output according to claim 6, it is characterised in that: in the step (3)
Position, the period of number acquisition adsorbed gas output and the number of output occurred according to recessed form is achieved in that
The abscissa corresponding period for the position that the recessed form occurs is the period of adsorbed gas output；
The number that the recessed form occurs is the number of adsorbed gas output.
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