CN112746838A - Method for judging compressibility of rocks of different well sections of horizontal well for developing natural fractured reservoir - Google Patents
Method for judging compressibility of rocks of different well sections of horizontal well for developing natural fractured reservoir Download PDFInfo
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Abstract
The invention provides a method for judging rock compressibility of different well sections of a horizontal well for developing a natural fractured reservoir. The method for judging the compressibility of rocks at different well sections of a horizontal well with natural fractures comprises the following steps: step 1: collecting rock debris samples at different well sections in the drilling process of the horizontal well; step 2: observing the rock debris sample by using an electron scanning microscope to obtain the natural crack development condition, the rock brittleness and the rock pore development process condition of the corresponding well section; and step 3: and calculating the compressibility index of the rock of the corresponding well section by a weight scoring method. According to the invention, the compressibility index of the rock at the horizontal section is obtained by collecting and analyzing the whole rock fragment sample at the horizontal section, so that the compressibility distribution of the rock at the horizontal section is determined, and the position with high compressibility index can be selected as much as possible to set a perforation point in the subsequent fracturing design, thereby completing the fracturing staged optimization design.
Description
Technical Field
The invention relates to the technical field of oil exploitation, in particular to a method for judging rock compressibility of different well sections of a horizontal well for developing a natural fractured reservoir.
Background
The reservoir matrix of the fractured volcanic reservoir has poor physical properties, natural fractures develop, the thickness of the reservoir is large, and reserves can be effectively used only by large-scale volume fracturing. The oil reservoir has shallow buried depth, hard and brittle reservoir rock, natural crack development and small bidirectional stress difference, is suitable for construction with large discharge capacity, increases the complexity of artificial cracks, realizes the reconstruction of a crack network and improves the reconstruction effect.
The current fracturing design method mainly selects an engineering dessert as a perforation point in a geological dessert according to the interpretation content of a conventional well logging curve and a gas logging result. Conventional well log interpretation includes: porosity, permeability, oil saturation, oil layer classification, rock mechanical properties and the like. Geological dessert selection is mainly considered: porosity, permeability, oil saturation, oil layer classification, and gas measurements. The engineered dessert is selected based on the mechanical properties of the rock, which are primarily well-interpreted, porosity of the well-interpreted.
For fractured volcanic oil reservoirs, the natural fracture development conditions of different well sections cannot be reflected by the conventional interpretation results, so the natural fracture development conditions cannot be considered by selecting the engineering dessert. The development condition of natural fractures is crucial to fracturing to form a complex fracture network and improve the horizontal section transformation effect, and is a factor which must be considered for optimizing the perforation position of the horizontal well of the fractured volcanic oil reservoir.
Patent document CN104749622B discloses "a quantitative characterization method of shale compressibility based on petrophysics". A quantitative characterization method of shale compressibility based on petrophysics is disclosed. The method comprises the following steps: (1) establishing a shale compressibility mathematical model; (2) analyzing the relation between the formation parameters and mechanics, and preferably selecting the formation mechanics parameter characterization factors; (3) regression fitting is carried out on a compressive strength elastic parameter representation formula, and a formation fracture pressure elastic parameter representation formula and a principal stress elastic parameter representation formula are established; (4) establishing a compressibility index representation formula and verifying and calculating a compressibility index comprehensive data body; (5) the formation compressibility is quantitatively characterized and predicted. According to the method, through multi-parameter analysis, effective characterization factors of the shale formation compressibility are selected, and a characterization formula of the shale compressibility index is constructed, so that quantitative characterization of the shale compressibility is realized, an identification standard of the shale compressibility is established, target optimization of a formation fracturing modification layer section is guided, the cost of shale exploration is reduced, and the success rate of the shale exploration is effectively improved. The method is only directed to shale reservoirs and therefore does not take into account the effect of natural fractures on compressibility. Applicability in fractured reservoirs is poor.
Patent document CN105626025B discloses a "method for evaluating fracturing compressibility of shale reservoir," which integrates two calculation methods of near well parameters and far well construction parameters, and finally gives a fracturing comprehensive compressibility index of shale reservoir by combining different weights of fracture lengths designed during fracturing design. The method for evaluating the compressibility has quantitative knowledge on the compressibility of the shale reservoir, and provides a certain guide basis for selection and optimization of the fracturing scale, the fracturing process, fracturing materials and the like when the fracturing scheme is optimally designed according to the magnitude of the comprehensive compressibility index. The method is suitable for selection and optimization of fracturing scale, fracturing process, fracturing materials and the like during optimization design, and does not relate to fracturing judgment of different well sections of the horizontal well and perforation position optimization.
Patent document CN105822292A discloses "a method for calculating shale gas reservoir compressibility evaluation by using logging data", which mainly includes (1) calculating shale brittleness index Brit by using logging data; (2) calculating a fracture toughness index Kn of the shale by using logging data; (3) and calculating a compressible index Frac through the shale brittleness index Brit and the rock fracture toughness index Kn, and establishing compressible index spatial distribution according to rock pressure mechanical parameters at different positions so as to evaluate the compressibility of the shale stratum of the block. The method mainly aims at shale gas reservoirs, and calculates compressibility only from the aspects of mechanical properties such as rock brittleness, fracture toughness and the like, and the method is not enough for considering pore development conditions and natural fracture development conditions.
Patent document CN106204303A discloses "a shale gas reservoir compressibility evaluation method based on weight assignment". According to geological dessert and engineering dessert factors, preferably selecting compressibility evaluation parameters, from the perspective of evaluating gas content and easy transformation potential of a shale reservoir, calculating the engineering dessert parameters by standardizing the geological dessert parameters and integrating mineral component content and mesoscopic mechanical parameters, constructing a compressibility evaluation model capable of continuously judging the reservoir, and only obtaining the total organic carbon content, vitrinite reflectivity and mineral component content of the shale reservoir to calculate and obtain a geological dessert compressibility evaluation index, an engineering dessert compressibility evaluation index and an integrated compressibility evaluation index so as to realize compressibility evaluation of the shale gas reservoir; the evaluation method can accurately divide the effective fracturing layer section and the shielding layer section and guide fracturing design and construction. The method aims at the shale gas reservoir, so the influence of the fracture on the compressibility is not considered, and the applicability of the method in the reservoir with natural fracture development is not strong.
Patent document CN106869911A discloses "an evaluation method for describing the compressibility of shale reservoirs". Collecting the data content of a well to be evaluated, wherein the data content comprises a well position design report book, logging data and logging data of the well to be evaluated, determining a shale reservoir and the vertical depth H in the middle of the shale reservoir according to the collected data, determining the formation pore fluid pressure gradient FPG of the shale reservoir, obtaining the rock density DEN of an overlying formation of the shale reservoir, and calculating the maximum horizontal stress Kimax and the minimum horizontal stress Kimin of the shale reservoir according to the FPG and the DEN; and then calculating the horizontal stress difference coefficient delta Ki of the shale gas reservoir to evaluate the compressibility of the shale reservoir, and outputting an evaluation result. According to the method, the horizontal ground stress difference coefficient delta Ki of the shale reservoir is calculated through parameters such as FPG (focal plane gas) and DEN (deep drawdown potential) and the compressibility of the shale reservoir is evaluated according to the delta Ki. The method aims at the shale gas reservoir, so the influence of the fracture on the compressibility is not considered, and the applicability of the method in the reservoir with natural fracture development is not strong.
Patent document CN106909758B discloses "a method for optimizing design of multi-stage clustering perforation positions of horizontal wells of tight oil reservoirs". Discloses a novel optimization design method for multi-section clustering perforation positions of a compact oil horizontal well, which sequentially comprises the following steps: (A) calculating a compressibility index profile of the horizontal segment based on the logging data; (B) calculating a physical index profile of the horizontal section based on the porosity, the permeability, the oil saturation and the natural fracture development condition; (C) determining compressibility and physical property evaluation standards of the horizontal segment by a probability statistical method, and determining each segment with excellent comprehensive score as an engineering dessert segment; (D) removing sections with poor cementing quality in each engineering dessert section, and determining the remaining sections as each fracturing subsection position; (E) in each section, based on the analysis and calculation of the crack induced stress field, the perforation cluster spacing range which is beneficial to the maximization of the transformed volume after pressing and can form a complex crack network is preferably selected; (F) and in each section, combining the comprehensive scoring result and the perforation cluster distance range, avoiding the position of a casing coupling, and finally determining the clustered perforation position in each section. The method considers natural cracks, rock properties and physical properties, but adopts an equal weight method, and does not consider the difference of influence degrees of various factors on compressibility.
Patent document CN107290799A discloses "a method for determining rock compressibility". The method comprises the following steps: calculating rock mechanical parameters of the measured rock under the buried depth of each stratum according to the acquired acoustic logging data, and calculating a first compressibility index of the target layer rock according to the rock mechanical parameters; calculating the peak compressive strength and the residual compressive strength of the target layer rock according to a preset compressive strength model, and determining a second compressibility index of the target layer rock according to the peak compressive strength and the residual compressive strength; and determining the comprehensive compressibility index of the target layer rock according to the first compressibility index and the second compressibility index, so as to judge the compressibility of the target layer rock according to the comprehensive compressibility index. The method overcomes the defect that the existing rock compressibility determination method is limited to consideration of elastic deformation parameters of the rock, extends the method to the evaluation of the elastic-plastic and plastic deformation stages, has wide application value, and especially has important significance to the evaluation of the deep shale gas compressibility. The method mainly considers the mechanical property of the rock to calculate the compressibility, and has weak applicability in the dense oil reservoir of crack development.
Patent document CN107327299A discloses "a method and apparatus for determining reservoir compressibility". The method comprises the following steps: determining a numerical value of a permeability heterogeneity parameter of the target reservoir based on the permeability at the sampling point position; wherein the permeability heterogeneity parameters comprise: the permeability variation coefficient, the permeability breakthrough coefficient and the permeability are extremely poor; determining the corresponding formation pressure retention of the target reservoir at the position of the target well based on the formation pressure at the position of the specified sampling point and the specified original formation pressure of the target reservoir; the specified original formation pressure indicates the formation pressure of the target reservoir when the target reservoir is not exploited; and determining the compressibility grade of the target reservoir based on the numerical value of the permeability heterogeneity parameter and the formation pressure retention degree. The method judges compressibility based on permeability heterogeneity and formation pressure retention degree, and has good adaptability in compact sandstone. But the weight degree of natural fractures and various factors is not considered, and the applicability of the reservoir to the dense fractured volcanic rock is poor.
Patent document CN107701179A discloses "a method for evaluating compressibility of shale gas reservoir based on conventional well logging data". The shale stratum compressibility evaluation method based on conventional logging information is characterized by collecting logging information of a well to be tested, wherein the logging information comprises natural gamma, uranium removed natural gamma, density and the like; distinguishing intervals of mudstone and shale by natural gamma GR and natural gamma KTH for removing uranium; normalizing the collected parameters; establishing a shale gas reservoir compressibility mathematical model according to the parameters; verifying the reliability of the model and optimizing stratum parameters by combining all the data; and judging whether the evaluation standard of the compressibility of the shale gas reservoir in the work area is established or not, entering the next step after the establishment, and entering the next step after the evaluation standard of the compressibility of the shale gas reservoir is not established according to the existing work area data. And quantitatively characterizing the compressibility of the reservoir according to the calculated BI value: and outputting an evaluation result. The method is suitable for the situation that the conventional logging technology cannot distinguish the development of natural fractures of different well sections of the horizontal well, so that the influence of the natural fractures cannot be considered in the compressibility judgment process.
Patent document CN108009705A discloses "a shale reservoir compressibility evaluation method based on support vector machine technology". Relates to a shale reservoir compressibility evaluation method based on a support vector machine technology. The method comprises the following steps: (1) firstly, carrying out quantitative analysis and uniaxial compression test on mineral components; (2) extracting logging characteristic parameters for identifying cracks; (3) calculating the maximum and minimum horizontal main stresses of different layers through a combined spring model, and then calculating the stress sensitivity; (4) establishing a compressibility evaluation model; (5) and establishing a discrete horizon stratum compressibility evaluation sample space, and simultaneously carrying out correlation analysis on the relationship between the compressibility evaluation result and the different response logging curves. The beneficial effects are that: the invention takes compressibility influence factors into consideration more completely, establishes a shale gas reservoir compressibility model from three aspects of brittleness index, natural fracture development degree and stress sensitivity, makes up the deficiency of the existing evaluation method in consideration of the factors, and better embodies the comprehensive ability of distinguishing the complex fracture network formed by the shale in volume fracturing. The weight coefficients of all factors of the method are obtained by inverting the actual compressibility evaluation result of the adjacent well, and are mainly aimed at shale reservoirs, and the applicability of the shale reservoirs in the volcanic reservoir developing in cracks is not strong.
Patent document CN108681635A discloses "a compact reservoir volume fracturing compressibility evaluation method". The method comprises the steps of respectively substituting the normalized Young modulus, shear modulus, tensile strength, compressive strength, rock I-type fracture toughness, rock II-type fracture toughness and brittleness index of each point position in the three-dimensional space of a target compact reservoir into different mutation models, calculating to obtain brittleness parameters, elasticity parameters and strength parameters, then constructing a volume fracturing compressibility evaluation model by using the brittleness parameters, the elasticity parameters and the strength parameters, calculating to obtain the volume fracturing compressibility coefficient of each point position in the three-dimensional space of the target compact reservoir, obtaining the three-dimensional space distribution of the compressibility index of the target compact reservoir, determining the compressible interval of the target compact reservoir, realizing quantitative evaluation on the volume fracturing compressibility of the compact reservoir, and solving the problems of overlarge determination subjectivity of the weight and incomplete parameter consideration in the prior art. The method has insufficient consideration on the influence of natural fractures and has low adaptability in fractured reservoirs.
Patent document CN109281662A discloses a method for determining relative compressibility indexes of reservoirs at different horizontal well sections, which provides a method for determining relative compressibility indexes of reservoirs at different horizontal well sections, comprising: step S1: calculating compressibility indexes x of reservoirs at different section positions of the horizontal well according to the influence factors of the compressibility of the reservoirs; step S2: and calculating the relative compressibility index d of the reservoir at different section positions according to the compressibility index x of the reservoir at different section positions obtained in the step S1. The invention solves the problems that the determination consideration factor of the compressibility index in the prior art is incomplete, and the absolute size of the compressibility index is only considered in the prior art, but the relative size of the compressibility index is not considered, namely the relative compressibility index is not considered. The method does not take into account the weight of each factor, nor the effect of natural fractures on compressibility.
Therefore, at present, no mature and uniform comprehensive evaluation method for reservoir rock compressibility evaluation exists.
Disclosure of Invention
The invention mainly aims to provide a method for judging the compressibility of rocks at different well sections of a horizontal well for developing a natural fractured reservoir, which can realize analysis of the compressibility of the rocks at different well sections of the horizontal well while drilling and can provide important technical support for fracture section design after well logging is finished.
In order to achieve the purpose, the invention provides a method for judging rock compressibility of different sections of a horizontal well for developing a natural fractured reservoir, which comprises the following steps: step 1: collecting rock debris samples at different well sections in the drilling process of the horizontal well; step 2: observing the rock debris sample by using an electron scanning microscope to obtain the natural crack development condition, the rock brittleness and the rock pore development process condition of the corresponding well section; and step 3: and calculating the compressibility index of the rock of the corresponding well section by a weight scoring method.
Further, in step 2, the natural fracture development condition is obtained by calculating the number of the micro-fractures of the sample, and the natural fracture development degree of the section of rock is divided into three grades, namely low, medium and high according to the number of the micro-fractures.
Further, the number of microcracks of the rock debris sample is less than 1, the number of microcracks is 1-5, the number of microcracks is medium, the number of microcracks is more than 5, and each grade is graded by 1, 2 and 3 in sequence.
Further, in step 2, the rock pore development process is measured by using the porosity obtained by well logging interpretation, and the rock pore development of the section is divided into three grades of low, medium and high according to the porosity.
Further, the porosity was low below 10%, medium between 10% and 15%, high above 15%, and scored 1, 2, and 3 points per level in this order.
Further, rock brittleness is calculated using poisson's ratio and elastic modulus interpreted from conventional well logs, wherein,
TBRIT＝(EBRIT+vBRIT)/2
EBRIT＝(E-Emin)/(Emax-Emin)
vBRIT＝(v-vmax)/(vmin-vmax)
wherein, TBRITNormalized rock brittleness; eBRITNormalized modulus of elasticity; v. ofBRITIs a normalized poisson's ratio; emaxAnd EminMaximum and minimum elastic moduli within a statistical range; v. ofmaxAnd vminThe maximum and minimum poisson's ratio within the statistical range.
Further, the rock brittleness is divided into three levels of low, medium and high according to the normalized rock brittleness, each level is sequentially divided into 1, 2 and 3, the normalized rock brittleness value is lower than 30, medium between 30 and 60 and high between 60.
Further, in step 3, an evaluation model is established by adopting a big data random forest algorithm, the influence of natural cracks, rock brittleness and pore development conditions on oil production is evaluated, and weight factors of the three factors are obtained, wherein the weight factor 1 of the natural cracks is 0.7, the weight factor 2 of the rock brittleness is 0.22, and the weight factor 3 of the rock pore development conditions is 0.08.
Further, the compressibility index of the rock is 1 × natural fracture development degree score + 2 × rock brittleness score + 3 × rock porosity score.
By applying the technical scheme, the compressibility index of the rock at the horizontal section is obtained by collecting and analyzing the whole rock fragment sample at the horizontal section, so that the compressibility distribution of the rock at the horizontal section is determined, and the position with high compressibility index can be selected as much as possible to set a perforation point in the subsequent fracturing design, thereby completing the fracturing subsection optimization design.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 schematically shows a flow chart of the method for determining rock compressibility of different sections of a horizontal well of a developing natural fractured reservoir according to the invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Referring to fig. 1, according to an embodiment of the invention, a method for determining rock compressibility of different well sections of a horizontal well for developing a natural fractured reservoir is provided. The method for judging the rock compressibility of different well sections of the horizontal well with the natural fractures comprises 3 steps.
Wherein, the step 1 is as follows: collecting rock debris samples at different well sections in the drilling process of the horizontal well; the step 2 is as follows: observing the rock debris sample by using an electron scanning microscope to obtain the natural crack development condition, the rock brittleness and the rock pore development process condition of the corresponding well section; the step 3 is: and calculating the compressibility index of the rock of the corresponding well section by a weight scoring method.
According to the invention, the compressibility index of the rock at the horizontal section is obtained by collecting and analyzing the whole rock fragment sample at the horizontal section, so that the compressibility distribution of the rock at the horizontal section is determined, and the position with high compressibility index can be selected as much as possible to set a perforation point in the subsequent fracturing design, thereby completing the fracturing staged optimization design.
Specifically, in step 2, the natural fracture development condition is obtained by calculating the number of the micro-fractures of the sample, and the natural fracture development degree of the section of rock is divided into three levels, namely low, medium and high through the number of the micro-fractures. The number of the microcracks of the rock debris sample is lower than 1, the number of the microcracks is 1-5, the number of the microcracks is medium, the number of the microcracks is higher than 5, and each grade is graded by 1, 2 and 3 in sequence.
The rock pore development process is measured by the porosity obtained by well logging explanation, and the rock pore development of the section is divided into three grades of low, medium and high according to the porosity. Wherein the porosity is lower than 10%, medium between 10% and 15%, high above 15%, and the grades are 1, 2 and 3 respectively.
The brittleness of the rock is calculated by adopting Poisson's ratio and elastic modulus obtained by interpreting a conventional well logging curve, wherein,
TBRIT＝(EBRIT+vBRIT)/2；
EBRIT＝(E-Emin)/(Emax-Emin)；
vBRIT＝(v-vmax)/(vmin-vmax)；
wherein T isBRITNormalized rock brittleness; eBRITNormalized modulus of elasticity; v. ofBRITIs a normalized poisson's ratio; emaxAnd EminMaximum and minimum elastic moduli within a statistical range; v. ofmaxAnd vminThe maximum and minimum poisson's ratio within the statistical range. In the actual production calculation, EmaxTake 8, EminValues of 1, vmaxValues of 0.4, vminThe value is 0.15.
When the design is implemented, the rock brittleness is divided into three levels of low, medium and high according to the normalized rock brittleness, each level is divided into 1, 2 and 3 in sequence, the normalized rock brittleness value is lower than 30, medium between 30 and 60 and high more than 60.
In the step 3, an evaluation model is established by adopting a big data random forest algorithm, the influence of natural cracks, rock brittleness and pore development conditions on oil production is evaluated, and weight factors of the three factors are obtained, wherein the weight factor of the natural cracks, namely the weight factor 1, is 0.7, the weight factor of the rock brittleness, namely the weight factor 2, is 0.22, and the weight factor of the rock pore development conditions, namely the weight factor 3, is 0.08.
The compressibility index of the rock calculated by the weight scoring method is as follows: the compressibility index is 1 × natural fracture development degree score + weight coefficient 2 × rock brittleness score + weight coefficient 3 × rock porosity score.
The compressibility index was divided into 3 points at full and 1 point at minimum. The higher the score is, the better the compressibility of the reservoir is, the more easily a complex seam network is formed, the modification volume is increased, and the better modification effect is obtained. And acquiring the compressibility distribution of the horizontal section rock through the collection and analysis of the whole horizontal section rock debris sample, and selecting the position with high score as much as possible to set perforation points in the subsequent fracturing design so as to complete the fracturing staged optimization design.
The following specific examples are provided to illustrate the method for determining rock compressibility of different sections of a horizontal well with natural fractures, according to the present invention, as follows:
the inclined depth of the point A is 1564m, the inclined depth of the point B is 2463m and the horizontal section is 899m in a rock-charcoal volcanic oil reservoir X well of a certain oil field. And collecting the logging rock debris sample, and making the rock debris sample which has the specification of 30mm multiplied by 30mm and is suitable for being observed by an electronic scanning microscope. The rock brittleness index of the corresponding well section is analyzed to be 35-76, the porosity is 3.8-21.0%, and the micro-crack number on the rock debris sample is 0-10.
The porosity of the well at the depth of 1582m is 13.1%, the rock pore development condition is 2, and the weight is 0.08; the number of the microcracks is 7, the natural crack development condition is 3, and the weight is 0.70; the rock brittleness index is 60.8, the rock brittleness score is 3, and the weight is 0.22. The compressibility index of the rock at that point was calculated to be 0.08 × 2+0.70 × 3+0.22 × 3 to 2.92.
The porosity of the well at 1712m depth is 10.2 percent, the rock pore development condition is 2, and the weight is 0.08; the number of the microcracks is 0, the development condition of the natural cracks is 1, and the weight is 0.70; rock brittleness index 56, rock brittleness score of 2, weight 0.22. The compressibility index of the rock at that point was calculated to be 0.08 × 2+0.70 × 1+0.22 × 2 to 1.30.
The method comprises the steps of analyzing logging rock debris samples while drilling to obtain natural fracture development conditions and rock pore development conditions, explaining the obtained rock brittleness in combination with logging, calculating compressibility values of rocks at different well sections of the horizontal well, achieving a perforation and segmentation scheme after the logging is completed, and ensuring the scientificity and timeliness of the fracturing design of the tight fractured volcanic reservoir.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. The method for judging the compressibility of rocks at different well sections of a horizontal well for developing a natural fractured reservoir is characterized by comprising the following steps of:
step 1: collecting rock debris samples at different well sections in the drilling process of the horizontal well;
step 2: observing the rock debris sample by using an electron scanning microscope to obtain the natural crack development condition, the rock brittleness and the rock pore development process condition of the corresponding well section;
and step 3: and calculating the compressibility index of the rock of the corresponding well section by a weight scoring method.
2. The method for judging the rock compressibility of different sections of the horizontal well for developing the natural fractured reservoir according to claim 1 is characterized in that in the step 2, the natural fractured development condition is obtained by calculating the number of the micro fractures of the sample, and the natural fractured development degree of the section of rock is divided into three grades of low, medium and high according to the number of the micro fractures.
3. The method for judging the rock compressibility of different sections of the horizontal well of the developing natural fractured reservoir according to claim 2, wherein the number of the micro fractures of the debris sample is less than 1, the number of the micro fractures is 1-5, the number of the micro fractures is more than 5, and each level is sequentially scored as 1, 2 and 3.
4. The method for judging the rock compressibility of different sections of the horizontal well for developing the natural fractured reservoir according to claim 1 is characterized in that in the step 2, the rock pore development process is measured by using the porosity obtained by well logging interpretation, and the rock pore development of the section is divided into three grades of low, medium and high according to the porosity.
5. The method for judging the rock compressibility of different well sections of the horizontal well for developing the natural fractured reservoir according to claim 4, wherein the porosity is low below 10%, medium between 10% and 15%, high above 15%, and each grade is graded as 1 grade, 2 grades and 3 grades in sequence.
6. The method for judging rock compressibility of different well sections of a horizontal well for developing a natural fractured reservoir according to claim 1, wherein rock brittleness is calculated by Poisson's ratio and elastic modulus obtained by interpreting a conventional well logging curve, wherein,
TBRIT＝(EBRIT+vBRIT)/2
EBRIT＝(E-Emin)/(Emax-Emin)
vBRIT＝(v-vmax)/(vmin-vmax)
wherein TBRIT is normalized rock brittleness; EBRIT is the normalized modulus of elasticity; vBRIT is normalized Poisson's ratio; emax and Emin are the maximum and minimum elastic moduli within the statistical range; vmax and vmin are the maximum and minimum poisson's ratio within the statistical range.
7. The method for judging the rock compressibility of different sections of the horizontal well for developing the natural fractured reservoir according to claim 6, wherein the rock brittleness is divided into three levels of low, medium and high according to the normalized rock brittleness, the grades of each level are 1 grade, 2 grades and 3 grades in sequence, the normalized rock brittleness value is lower than 30, medium between 30 and 60 and higher than 60.
8. The method for judging the rock compressibility of different sections of the horizontal well for developing the natural fractured reservoir according to claim 1 is characterized in that in step 3, an evaluation model is established by adopting a big data random forest algorithm, the influence of natural fractures, rock brittleness and pore development conditions on oil production is evaluated, and weight factors of three factors are obtained, wherein the weight factor of the natural fractures, namely the weight factor 1, is 0.7, the weight factor of the rock brittleness, namely the weight factor 2, is 0.22, and the weight factor of the rock pore development conditions, namely the weight factor 3, is 0.08.
9. The method for judging the compressibility of rocks at different sections of a horizontal well of a developing natural fracture reservoir according to claim 8, wherein a compressibility index of the rocks is 1 x natural fracture development degree score + weight coefficient 2 x rock brittleness score + weight coefficient 3 x rock pore score.
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