Method and system for analyzing friction resistance in multi-stage fracturing of horizontal wells

Abstract

The present invention discloses a method for analyzing friction resistance of multi-stage fracturing construction of horizontal wells, including: collecting and counting fracturing construction data, based on which, recording the data of changes in wellhead construction pressure with different horizontal fracturing stages under the action of injection pre-fluid displacement and / or sand-carrying liquid-sand ratio, and drawing corresponding curves; determining the total throttling pressure drop corresponding to the front-stage sliding sleeve through which the fracturing fluid reaches the target well section sliding sleeve opening position according to the manifold structure data, and correcting the current change curve according to the total throttling pressure drop; performing regression analysis on the wellhead pressure correction curve, and using the analysis results, obtaining the friction resistance pressure drop gradient along the horizontal well fracturing construction under corresponding conditions from the sand-carrying liquid-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed. The present invention can simply, quickly and accurately calculate the fracturing construction friction resistance pressure drop of horizontal wells under different formation conditions at different sand ratios and different displacements, and can be applied on the fracturing site.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method and a system for analyzing friction resistance in multi-stage fracturing construction of horizontal wells. Background Art

[0002] During the fracturing construction process, due to the high-speed flow of the fracturing fluid in the fracturing manifold, the collision between the viscoelastic liquid particles, the collision of the proppant solid particles in the sand-carrying fluid, the sedimentation of the proppant particle monomers due to gravity, and the friction between the liquid and the inner wall of the pipe string all consume a certain amount of energy, resulting in pipeline pressure loss, increasing the energy consumption of the power equipment, and affecting the stability of the overall fracturing system construction, which is reflected in the construction data as the frictional pressure drop along the way. There are many factors that affect the frictional pressure drop along the way, including the thermodynamic instability and complex rheological properties of the fracturing fluid itself, which makes its flow properties in the wellbore different from those of conventional pseudoplastic fluids, the relative velocity of the liquid, the characteristic parameters of the fluid, the flow state, the mixing sand ratio, the local temperature and the special structural characteristics of the manifold, etc. These factors themselves are a dynamically changing process and cannot be described and predicted by a single parameter.

[0003] The friction pressure drop analysis of staged fracturing in horizontal wells is an important input parameter for optimizing the process parameters of horizontal well fracturing. It is also an important indicator for evaluating the performance of fracturing fluids, optimizing fracturing equipment and tubing, and has a significant impact on the calculation of the breakdown pressure and operation pressure of fracturing construction.

[0004] In the prior art, although the research on construction friction calculation has received more and more attention, the calculation method for the construction friction of horizontal well multi-stage fracturing still has the following defects: (1) The calculation process only considers a single influencing factor, which makes the calculation result deviate greatly from the actual situation, and it is difficult to calculate the horizontal segment fracturing friction pressure drop that is consistent with the actual production on site; (2) The calculation method is too complicated and it is difficult to fully reflect the factors affecting the friction pressure drop during the construction of horizontal well multi-stage fracturing, and its application in the actual fracturing construction site is restricted; (3) It is limited to the calculation of horizontal well drilling friction, and does not involve the friction pressure drop during the construction of multi-stage fracturing. Therefore, there is no mature, reliable, and simple calculation method that can meet the needs of on-site application in the existing calculation and analysis methods of the friction pressure drop along the fracturing fluid in fracturing construction. Summary of the invention

[0005] One of the technical problems to be solved by the present invention is the need to provide a simple and reliable friction pressure drop calculation method that can reflect the actual situation of on-site fracturing construction in response to the needs of on-site development and reservoir transformation, so as to provide guiding suggestions for the formulation of on-site fracturing construction plans in oil fields and the adjustment of process plans.

[0006] In order to solve the above technical problems, the present invention provides a method for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells, comprising: step 1, collecting and counting fracturing construction data, based on which, recording the wellhead construction pressure data under the influence of the injection pre-fluid displacement and / or the sand-carrying liquid-sand ratio change, and drawing the corresponding curve of the wellhead construction pressure changing with the fracturing stage of different horizontal sections; step 2, according to the manifold structure data, determining the throttling total pressure drop corresponding to the front section sliding sleeve passed by the fracturing fluid when it reaches the target well section sliding sleeve opening position, and correcting the wellhead construction pressure change curve according to the throttling total pressure drop; step 3, performing regression analysis on the wellhead pressure correction curve, and using the analysis results, obtaining the friction resistance pressure drop gradient along the horizontal well fracturing construction under corresponding conditions from the sand-carrying liquid-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed.

[0007] Preferably, in step 2, the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well is determined; the inner diameter of each ball seat passed by the fracturing fluid when reaching the target well section sleeve opening position, and the corresponding sleeve throttling pressure drop when passing each ball seat are screened out from the construction data, and based on the distance, the total throttling pressure drop based on the current well section fracturing construction is calculated.

[0008] Preferably, the step 2 includes: selecting the wellhead construction pressure data corresponding to the same displacement and / or sand ratio conditions during the entire fracturing construction process from the wellhead construction pressure change curve, and based on this, drawing a construction pressure to-be-corrected curve under the current displacement and / or sand ratio combination conditions, and further obtaining multiple construction pressure to-be-corrected curves under different displacement and / or sand ratio combination conditions; according to the throttling total pressure drop, correcting each wellhead construction pressure data in the construction pressure to-be-corrected curve under each combination condition, and drawing the wellhead pressure correction curve under each combination condition based on the corrected wellhead construction pressure data.

[0009] Preferably, further, the difference operation is performed between each wellhead construction pressure data and the total throttling pressure drop under the fracturing construction of the corresponding well section to obtain the corresponding wellhead construction pressure correction data, based on which the wellhead pressure correction curve is drawn.

[0010] Preferably, in the step three, based on the position in the wellhead pressure correction curve and the corrected wellhead construction pressure data, the least squares method is used to perform linear fitting analysis on the wellhead pressure correction curve to obtain a corresponding linear regression result; the sand ratio data to be analyzed or the pre-fluid displacement to be analyzed that meets the current fracturing construction requirements is determined, and based on this, according to the linear regression result, the corresponding regression coefficient is determined to represent the friction pressure drop gradient along the horizontal well fracturing construction that meets the conditions to be analyzed.

[0011] On the other hand, the present invention also proposes a system for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells, including: a construction pressure curve drawing module, which collects and counts the fracturing construction data, based on which, records the wellhead construction pressure data under the influence of the injection pre-fluid displacement and / or the change of the sand-carrying liquid-sand ratio, and draws the corresponding curve of the wellhead construction pressure changing with the fracturing stage of different horizontal sections; a construction pressure curve correction module, which determines the throttling total pressure drop corresponding to the front section sliding sleeve passed by the fracturing fluid when it reaches the target well section sliding sleeve opening position according to the manifold structure data, and corrects the wellhead construction pressure change curve according to the throttling total pressure drop; a friction resistance pressure drop determination module along the way, which performs regression analysis on the wellhead pressure correction curve, and uses the analysis results to obtain the friction resistance pressure drop gradient along the horizontal well fracturing construction under corresponding conditions from the sand-carrying liquid-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed.

[0012] Preferably, the construction pressure curve correction module includes: a construction distance determination unit, which determines the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well; a total throttling pressure drop generation unit, which filters out from the construction data the inner diameter of each ball seat passed by the fracturing fluid when reaching the target well section sliding sleeve opening position, and the corresponding sliding sleeve throttling pressure drop when passing each ball seat, and calculates the total throttling pressure drop based on the current well section fracturing construction according to the distance.

[0013] Preferably, the construction pressure curve correction module also includes: a curve generation unit to be corrected, which selects the wellhead construction pressure data corresponding to the same displacement and / or sand ratio conditions during the entire fracturing construction process from the wellhead construction pressure change curve, and based on this, draws the construction pressure curve to be corrected under the current displacement and / or sand ratio combination conditions, and further obtains multiple construction pressure curves to be corrected under different displacement and / or sand ratio combination conditions; a correction result generation unit, which corrects each wellhead construction pressure data in the construction pressure curve to be corrected under each combination condition according to the throttling total pressure drop, and draws the wellhead pressure correction curve for each combination condition according to the corrected wellhead construction pressure data.

[0014] Preferably, the correction result generating unit further performs a difference operation on each wellhead construction pressure data and the total throttling pressure drop under the fracturing construction of the corresponding well section to obtain corresponding wellhead construction pressure correction data, based on which, the wellhead pressure correction curve is drawn.

[0015] Preferably, the along-the-line friction pressure drop determination module comprises: an analysis result generation unit, which, based on the position in the wellhead pressure correction curve and the corrected wellhead construction pressure data, uses the least squares method to perform linear fitting analysis on the wellhead pressure correction curve to obtain a corresponding linear regression result; an along-the-line friction pressure drop gradient generation unit, which determines the sand ratio data to be analyzed or the pre-fluid displacement to be analyzed that meets the current fracturing construction requirements, and based on this, determines the corresponding regression coefficient according to the linear regression result to represent the along-the-line friction pressure drop gradient of the horizontal well fracturing construction that meets the conditions to be analyzed.

[0016] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0017] The present invention proposes a method and system for analyzing friction resistance in multi-stage fracturing of horizontal wells. The method includes: collecting and statistically analyzing on-site construction data, drawing construction pressure change curves, correcting construction curves, and regression analysis of friction resistance and pressure drop data. The present invention can simply, quickly and accurately calculate the friction resistance and pressure drop of fracturing construction of horizontal wells under different formation conditions at different sand ratios and different displacements, and can be promoted and applied at the fracturing site to provide guiding suggestions for the calculation of on-site fracturing construction pressure and fracture pressure, as well as the designation of fracturing construction plans and the optimization and adjustment of process plans.

[0018] Other advantages, objectives, and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the following description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 This is a step diagram of a method for analyzing friction resistance in multi-stage fracturing construction of horizontal wells according to an embodiment of the present application.

[0021] Figure 2 It is a schematic diagram of the friction curve along the way before the throttling pressure drop correction in the method for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells in an embodiment of the present application.

[0022] Figure 3 It is a schematic diagram of the friction curve along the way after the throttling pressure drop correction in the method for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells in an embodiment of the present application.

[0023] Figure 4 This is a first example schematic diagram of the friction pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application.

[0024] Figure 5 This is a second example schematic diagram of the friction pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application.

[0025] Figure 6 This is a third example schematic diagram of the friction resistance and pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application.

[0026] Figure 7 This is a module block diagram of a system for analyzing friction resistance in multi-stage fracturing construction of horizontal wells according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0028] In order to solve the problems in the above-mentioned background technology, the present invention proposes a method and system for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells. For horizontal well fracturing construction, due to the particularity of horizontal wells and the particularity of multi-stage fracturing construction, theoretically, the fracturing friction resistance of different sections should also show certain characteristics, and these characteristics provide valuable data for the calculation and analysis of fracturing fluid friction resistance. The construction data of horizontal well multi-stage fracturing has three characteristics: ① The fracturing fluid system in different fracturing stages is relatively stable, and the vertical well section and horizontal section tubing remain unchanged during the construction process, so the internal friction coefficient of the tubing is the same; ② The physical properties of the reservoir are small, which is manifested in the closure stress, fracture initiation pressure, pump stop pressure, etc. are relatively close, so the water horsepower required to open the reservoir is relatively close, making the assumptions more reasonable; ③ The fracturing pumping procedures of each section are similar, and the relevant data of the same sand-carrying fluid concentration in different levels of fracturing construction can be selected. Based on this, according to the characteristics of horizontal well fracturing construction, the present invention simplifies the influencing factors of friction analysis, so that the friction change along the horizontal well section at different fracturing fluid injection stages is mainly affected by the sand ratio in the fracturing fluid (especially the sand ratio of the sand-carrying fluid), the construction displacement (especially the pre-fluid displacement), the ball seat throttling and the horizontal section length. Based on the friction pressure gradient method, the present invention analyzes and calculates the friction pressure drop of multi-stage fracturing construction in horizontal wells in combination with the actual production on site.

[0029] Specifically, the present invention is different from various theoretical calculation methods for calculating friction along the way. The method provided by the present invention is mainly formed by analyzing the pressure curve of the wellhead fracturing construction of the horizontal well to form the understanding and method. Due to the flow of downhole fracturing fluid in the tubing, the friction factor generated along the way will be reflected in the wellhead construction pressure data. Therefore, the present invention first analyzes the wellhead construction pressure data at each moment in the fracturing process of each well section, so as to draw a curve of the wellhead construction pressure data changing with the fracturing construction stage of each well section in the entire fracturing construction; then, in the stage of injecting different types of fracturing fluids during the fracturing process of each well section, the total throttling pressure drop in the tubing corresponding to each fracturing fluid when reaching the target well section position is calculated to correct the comprehensive wellhead construction pressure curve, so as to obtain the wellhead construction pressure correction curve for different pre-fluid displacements and / or different sand-carrying fluid combinations; finally, a plurality of corrected pressure curves are subjected to linear regression processing, and the sand-carrying fluid-sand ratio data to be analyzed and / or the fracturing fluid displacement to be analyzed of the current horizontal well fracturing construction are determined according to the actual requirements of field development and reservoir transformation, so as to obtain the corresponding horizontal well fracturing construction friction pressure drop gradient data along the way according to the regression results. In this way, the above technical solution provides a method for calculating the friction resistance of horizontal well fracturing that is both in line with the actual oil field production and simple and feasible. It calculates and analyzes the friction resistance of multi-stage fracturing construction in horizontal wells, providing a basis for efficient on-site fracturing construction.

[0030] Embodiment 1

[0031] Figure 1 This is a step diagram of a method for analyzing friction resistance of multi-stage fracturing in horizontal wells according to an embodiment of the present application. Figure 1 The friction analysis method in the embodiment of the present invention is described. Step S110 collects and counts the fracturing construction data, based on which, the data of the wellhead construction pressure changes with the fracturing stages of different horizontal sections under the effect of the displacement of the injected pre-fluid and / or the change of the sand-carrying liquid-sand ratio are recorded and the corresponding curves are drawn, wherein the displacement of the injected pre-fluid and / or the change range of the sand-carrying liquid-sand ratio meet the current fracturing construction requirements; Step S120 determines the corresponding front-segment sliding sleeve that the fracturing fluid passes through when it reaches the opening position of the sliding sleeve of the target well section (in the current well section fracturing stage) according to the manifold structure data in the construction data. The throttling total pressure drop is obtained, and the wellhead construction pressure change curve is corrected according to the throttling total pressure drop to obtain a plurality of wellhead pressure correction curves for different pre-fluid displacements and / or different combinations of sand-carrying liquid-to-sand ratios; step S130 performs regression analysis on the plurality of wellhead pressure correction curves obtained in step S120, and uses the current analysis result to obtain the friction pressure drop gradient along the horizontal well fracturing construction under corresponding conditions from the sand-carrying liquid-to-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed that meet the current fracturing construction requirements.

[0032] The above steps S110 to S130 are described in detail below.

[0033] Generally, the fracturing construction process includes well section fracturing construction for each horizontal well section respectively, and each well section fracturing construction includes the stages of sequentially injecting different types of fracturing fluids, including the stages of sequentially injecting pre-fluid, sand-carrying fluid and displacement fluid. The pre-fluid is mainly used to press open the formation to achieve fracture formation, and the sand-carrying fluid is a liquid that brings the proppant (generally ceramsite or quartz sand) into the fracture. The pre-fluid and the sand-carrying fluid have different chemical components, and the performance parameters of the liquids have differences in viscosity and temperature resistance and shear resistance, and the friction resistance during the construction process is different. Since the sand-carrying fluid contains proppant, the density of the sand-carrying fluid is different when the sand-carrying fluid is injected, which will affect the real-time display change of the wellhead pressure. In addition, when the pre-fluid is input, the display of the wellhead construction pressure will also be affected due to the different injection displacement. In other words, the factors affecting the friction resistance pressure drop of the fracturing fluid along the multi-stage segmented fracturing construction include the displacement change during the injection of the pre-fluid and the change of the sand concentration during the injection of the sand-carrying fluid.

[0034] In step S110, the construction requirements of the current fracturing construction or the overall fracturing construction process need to be determined first, wherein the construction requirements at least include the total injection displacement of the pre-fluid required for each well section fracturing construction stage, and the different concentrations of the sand-carrying fluid required for pumping in each fracturing construction stage. After the entire fracturing construction is completed, the field construction data of the entire fracturing construction is collected and counted. Table 1 is an example of the statistical results of the field construction data of the staged fracturing of a horizontal well.

[0035] Table 1 Statistics of staged fracturing construction data of a horizontal well

[0036]

[0037] Among them, the different concentrations of different sand-carrying fluids in Table 1 include: the (average) wellhead construction pressure corresponding to the sand-carrying fluid (6%), the (average) wellhead construction pressure corresponding to the sand-carrying fluid (12%), etc., and the percentages represent different sand ratio information. Due to the complex wellbore trajectory of the extended displacement well, the different construction conditions, and the influence of the rheological properties of the fracturing fluid, the traditional pressure gradient method cannot accurately predict the surface construction pressure of the extended displacement horizontal well. Therefore, the embodiment of the present invention adopts a method for analyzing the changes in the pre-fluid construction pressure data (indicating the corresponding wellhead pressure data when the pre-fluid is injected, and the corresponding wellhead pressure data also changes due to the change in the injection displacement) and the sand-carrying fluid construction pressure data (indicating the corresponding wellhead pressure data when the sand-carrying fluid with different sand ratio contents is injected, and the corresponding wellhead pressure data also changes due to the change in the sand ratio content).

[0038] Specifically, in the actual fracturing fluid pumping process, since the displacement of the pre-fluid injection process in the general hydraulic fracturing construction process is gradually increased from small to reach the total displacement of the pre-fluid injection required for the current well section fracturing to meet the construction requirements of the well section, according to the construction process of the current fracturing well section in different fracturing stages, the change of the wellhead construction pressure (data) corresponding to different pre-fluid displacements is reflected. In addition, in the actual fracturing fluid pumping process, the sand ratio content of the sand-carrying fluid in the sand-adding process is also increased from low to high. This process traverses all the sand ratio concentrations required for the fracturing process of the current well section to meet the construction requirements of the well section. According to the construction process of the current fracturing well section in different fracturing stages, the change of the wellhead construction pressure (data) corresponding to different sand ratio contents in the sand-adding process of pumping the sand-carrying fluid under the same pre-fluid displacement conditions is reflected. Therefore, the wellhead construction pressure data reflects the changes in the combination of different pre-fluid displacements (when the displacement data changes) and / or sand-carrying fluids with different sand ratio contents (when the sand ratio content data changes) during the fracturing construction process of each well section downhole, and the oil pressure value corresponding to each fracturing moment (or each fracturing construction position, the fracturing construction position is the real-time position where the fracturing fluid arrives downhole) detected by the fluid pumping device (not shown) at the wellhead.

[0039] Furthermore, the curve of the wellhead construction pressure changing with the fracturing stages of different horizontal sections described in the present invention, that is, the wellhead construction pressure change curve, is the oil pressure value corresponding to each fracturing moment in the entire fracturing process detected by the wellhead fluid pumping device, and represents the curve of the real-time wellhead construction pressure changing with the fracturing moment in each well section fracturing construction stage.

[0040] Then, the wellhead construction pressure data corresponding to each well section fracturing construction stage are connected into a wellhead construction pressure change curve according to different well section positions (or fracturing time). Among them, the wellhead construction pressure change curve is along the horizontal wellbore direction, which mainly refers to the pressure change curve of the wellhead construction pressure of each level of fracturing according to the position of the horizontal wellbore. The specific position is the position where the sliding sleeve is opened, which is also the position where the crack starts, and it can also be the downhole position where the fracturing fluid reaches corresponding to the fracturing construction time. Since it is necessary to inject different displacements of pre-fluid and different concentrations of sand-carrying fluid (the concentration here refers to different sand ratio contents) of sand-carrying fluid in each well section fracturing construction stage, the corresponding fluid generates corresponding friction resistance along the way in the tubing string, and due to the differences in pre-fluid displacement, sand-carrying fluid concentration, fracturing fluid flow distance, and the number of ball seat throttling components passed by the fracturing fluid, the value of the wellhead construction pressure data at different fracturing moments in each well section fracturing is constantly changing. This change accurately represents the different degrees of influence of each well section fracturing stage on the friction resistance along the way of the fracturing fluid. Therefore, the embodiment of the present invention obtains a wellhead construction pressure change curve that represents the overall fracturing construction process, so that this curve can be used as the basis for analyzing the friction resistance of multi-stage segmented fracturing construction in horizontal wells.

[0041] Next, the process proceeds to step S120. In each stage of staged fracturing, the surface pressure data of the pre-fluid injection stage is counted, and the wellhead construction pressure change curve obtained in step S110 is corrected to obtain a wellhead pressure correction curve for different pre-fluid displacements and / or different combinations of sand-carrying liquid-to-sand content. During the injection of pre-fluid and the injection of sand-carrying fluid in the fracturing process of each well section, various types of fracturing fluids flow into the tubing and pass through various types of sleeves when reaching the well section position of the current well section fracturing stage. These sleeve components have a throttling effect, which causes a corresponding non-negligible pressure drop effect on the wellhead construction pressure. This pressure drop caused by the throttling effect is irrelevant to the friction resistance along the way caused by the fracturing fluid flowing into the tubing. Therefore, in order to improve the accuracy of the final friction resistance analysis result along the way, it is necessary to obtain the total throttling pressure drop corresponding to the front end sleeve passed by the fracturing fluid when it reaches the opening position of the sleeve of the target well section during fracturing construction in step S120. This factor is irrelevant to the result of the friction resistance analysis along the way, and this total pressure drop value is used to correct the above-mentioned wellhead construction pressure change curve.

[0042] Specifically, first, it is necessary to determine the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well, and then, screen out the inner diameter of each ball seat passed by the fracturing fluid when reaching the target well section sleeve opening position, and the corresponding sleeve throttling pressure drop when passing each ball seat from the construction data, and calculate the total throttling pressure drop based on the above distance (the distance from the current construction well section position to the starting position of the horizontal well).

[0043] Then, the wellhead construction pressure data corresponding to the same displacement and / or sand ratio content conditions during the entire fracturing construction process are screened out from the wellhead construction pressure change curve obtained in the above step S110. Based on this, according to different well section positions (or fracturing times), a construction pressure curve to be corrected under the current displacement and / or sand ratio combination conditions is drawn, and multiple construction pressure curves to be corrected under different pre-fluid displacement and / or sand ratio content combinations are further obtained. Specifically, in the pre-fluid pumping stage during the fracturing construction process of each well section, since the sand-carrying fluid pumping process has not yet been implemented for the well section, it is necessary to obtain the wellhead construction pressure data corresponding to the same displacement conditions during the entire fracturing construction process from the above wellhead construction pressure change curve, draw a construction pressure curve to be corrected under the current displacement conditions, and further obtain a number of construction pressure curves to be corrected under different displacements. That is to say, during the fracturing construction process of each well section, according to the pre-fluid construction pressure data under different pre-fluid displacements pumped (that is, the wellhead construction pressure data corresponding to the fluid pumping device at the wellhead when pumping the pre-fluid), a curve of the pre-fluid construction pressure data under each pre-fluid displacement as the segmented fracturing position changes, that is, the construction pressure to be corrected curve.

[0044] In addition, in the stage of pumping sand-carrying fluid during the fracturing construction of each well section, since the pre-fluid has been pumped for the well section, it is necessary to read the wellhead construction pressure data corresponding to the same pre-fluid (total) displacement and sand ratio content during the entire fracturing construction process from the above-mentioned wellhead construction pressure change curve, so as to draw a construction pressure to be corrected curve under the current displacement and sand ratio conditions, and further, obtain a number of construction pressure to be corrected curves under different displacements and sand ratio conditions. That is to say, in the fracturing construction process of each well section, according to a certain pre-fluid displacement (in the actual fracturing process, usually when pumping sand-carrying fluids of different concentrations, the pumping displacement remains unchanged, so the fluid pumping displacement of the current sand-carrying fluid pumping stage is unchanged, and the variable of this stage is the sand ratio concentration) and the construction pressure data of sand-carrying fluids of different concentrations (i.e., when pumping sand-carrying fluids, the wellhead construction pressure data corresponding to the fluid pumping device at the wellhead) , A curve of the sand-carrying fluid construction pressure data under each concentration and pre-fluid displacement combination condition with the change of the staged fracturing position is constructed.

[0045] Figure 2 This is a schematic diagram of the friction curve along the way before the throttling pressure drop correction in the method for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells in the embodiment of the present application. Figure 2 As shown, Figure 2The curve of the sand-carrying fluid construction pressure data (sand-carrying fluid static pressure) under each concentration and certain pre-fluid displacement combination before throttling pressure drop correction and the change with the staged fracturing position is shown. For the same well section fracturing operation, the corresponding pre-fluid displacement that has been pumped during the sand-carrying fluid pumping process remains unchanged (constant). The horizontal axis represents the position of the sand-carrying fluid flowing through the current horizontal well, and the vertical axis represents the wellhead construction pressure value when the sand-carrying fluid is injected. Among them, the sand-carrying fluid concentrations include: 6%, 12%, 18%, and 24%.

[0046] Next, according to the factor data unrelated to the results of the friction analysis along the way, each wellhead construction pressure data (at each fracturing construction moment or each fracturing construction position) in the construction pressure to be corrected curve under each combination condition is corrected to obtain the corrected wellhead construction pressure data. Based on this, according to different well section positions (or fracturing times), a wellhead pressure correction curve for each construction pressure to be corrected curve is drawn, thereby obtaining the wellhead construction pressure correction curve for different front fluid displacements and different sand-carrying fluid combinations. Specifically, in an embodiment of the present invention, the factor data unrelated to the results of the friction analysis along the way is preferably the total throttling pressure drop corresponding to all types of sliding sleeves in the front section that the fracturing fluid passes through when reaching the opening position of the sliding sleeve in the target well section during the construction of different fracturing well sections. Since the construction pressure to be corrected curve under each combination condition is generated based on the wellhead construction pressure data to be corrected under the same combination condition in the fracturing construction of all well sections, and since the total throttling pressure drop corresponding to the fracturing construction of different well sections is different due to the different opening positions of the sliding sleeve, in the embodiment of the present invention, it is necessary to perform a difference operation on the wellhead construction pressure data at each fracturing construction moment or each fracturing construction position in the construction pressure to be corrected curve under each combination condition and the total throttling pressure drop corresponding to the fracturing construction of the corresponding well section, respectively, to obtain the wellhead pressure correction data (i.e., the corrected wellhead construction pressure data) at each fracturing construction moment or each fracturing construction position under each combination condition, and further draw a wellhead pressure correction curve for each construction pressure to be corrected curve.

[0047] Figure 3 It is a schematic diagram of the friction curve along the way after the throttling pressure drop correction in the method for analyzing the friction resistance of multi-stage fracturing construction in horizontal wells in an embodiment of the present application. Figure 3 The curve of the construction pressure data (sand-carrying fluid pressure) of each concentration of sand-carrying fluid after throttling pressure drop correction versus staged fracturing position is shown. The horizontal axis represents the position where the sand-carrying fluid flows through the current horizontal well, and the vertical axis represents the corrected wellhead construction pressure data when the sand-carrying fluid is injected.

[0048] In one embodiment, Table 2 shows the statistics and correction of the wellhead pressure when a pad fluid is injected into a horizontal well.

[0049] Table 2 shows the statistics and correction of the wellhead pressure of a horizontal well injected with pre-fluid

[0050]

[0051] In this way, after excluding the factor data irrelevant to the results of the friction analysis along the way, each wellhead pressure correction data obtained is expressed as the fluid friction pressure drop data at the current fracturing construction time or construction position. Therefore, each wellhead pressure correction curve is a curve of the fluid friction pressure drop along the way changing with the fracturing construction time or fracturing construction position under the current front fluid displacement and / or sand ratio content combination conditions. Therefore, these correction curves are used to construct a regression model for analyzing the friction along the way of horizontal well fracturing construction, so that the model can be used to directly know the corresponding friction pressure drop gradient results along the way under the conditions of the sand ratio of the sand-carrying fluid to be analyzed and / or the fracturing fluid displacement to be analyzed under the current fracturing construction requirements.

[0052] After obtaining the wellhead construction pressure correction curve for different pre-fluid displacements and / or different sand-carrying fluid combinations, the process proceeds to step S130. First, based on the position in each wellhead pressure correction curve that meets the current fracturing construction requirements and the corrected wellhead construction pressure data (wellhead construction pressure correction data), the least squares method is used to perform regression fitting analysis of the horizontal well friction pressure drop data to obtain the corresponding regression analysis results, i.e., the friction analysis model for multi-stage fracturing construction of horizontal wells. Then, the sand ratio concentration data to be analyzed or the pre-fluid displacement to be analyzed in the current fracturing construction process is determined. Based on this, the corresponding regression model coefficient is determined according to the above linear regression results, thereby obtaining the friction pressure drop gradient along the horizontal well fracturing construction that meets the conditions to be analyzed.

[0053] Among them, it should be noted that the friction analysis model for multi-stage fracturing construction of horizontal wells is a model obtained by regression analysis of the above-mentioned multiple wellhead pressure correction curves for analyzing the friction pressure drop gradient along the process under the current construction demand conditions. It can directly determine the comprehensive friction pressure drop gradient of the fracturing construction of the target well under the current pre-fluid displacement conditions to be analyzed according to the pre-fluid displacement required for this analysis in the field fracturing construction requirements, or directly determine the comprehensive friction pressure drop gradient of the fracturing construction of the target well under the current sand ratio concentration conditions according to the sand-carrying fluid concentration required for this analysis in the field fracturing construction requirements. In an embodiment of the present invention, the comprehensive friction pressure drop gradient represents the construction pressure change mainly caused by the friction of the tubing per 100 meters, and can also be used to characterize the independent variable of the construction pressure change caused by the friction of the tubing during the horizontal well fracturing process according to the length of the horizontal well section (construction location or time).

[0054] Specifically, in the process of linear regression curve fitting analysis using the least square method for the corrected wellhead pressure correction curve, according to a series of data of the position variable x and the wellhead pressure variable y obtained in each wellhead pressure correction curve, (x1, y1), (x2, y2) ... (xm, ym), these data are regressed using the least square method to obtain a friction analysis model for multi-stage fracturing construction of horizontal wells based on the fitting linear formula (y = Kx + b). Then, after determining the current displacement of the pre-fluid to be analyzed, the friction coefficient K along the way under the current pre-fluid displacement condition is obtained according to the above analysis model, thereby obtaining the (comprehensive) friction pressure drop gradient along the way of horizontal well fracturing construction (the construction pressure change caused by the friction resistance of the pipe string every 100 meters) that meets the current displacement condition of the pre-fluid to be analyzed. In addition, after determining the current sand content to be analyzed, the friction coefficient K along the way under the current sand concentration conditions is obtained according to the above analysis model, thereby obtaining the (comprehensive) friction pressure drop gradient along the way of horizontal well fracturing construction (the construction pressure change caused by the friction of the tubing string every 100 meters) that meets the current sand concentration conditions to be analyzed.

[0055] Figure 4 This is a first example schematic diagram of the friction pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application. Figure 4 The graph shows the change demand curve 4c of the sand content ratio in the fracturing construction of a horizontal well, the change demand curve 4b of the fracturing fluid displacement (different fracturing fluid types correspond to different pumping stages when pumping fracturing fluid, such as the fracturing fluid displacement during the pre-fluid pumping stage represents the pre-fluid displacement that has a greater impact on the friction analysis results along the process, and the fracturing fluid displacement during the sand-carrying fluid pumping stage represents the sand-carrying fluid displacement with almost no change in the pumping displacement), and the wellhead construction pressure data (before correction) displayed in real time by the fluid pumping device at the wellhead during the entire fracturing construction process. When the pre-fluid displacement to be analyzed is 3m 3 / min, the friction pressure drop gradient along the horizontal well fracturing construction that meets the current fracturing construction requirements obtained by the analysis method of the present invention is 0.58MPa / 100m, wherein the average sand-carrying fluid concentration in the current fracturing construction process is 19%.

[0056] Figure 5 This is a second example schematic diagram of the friction pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application. Figure 5 The graph 5c shows the demand curve 5b for the change of sand content in the fracturing construction of a horizontal well, the demand curve 5b for the change of fracturing fluid displacement, and the curve 5a showing the change of wellhead construction pressure data (before correction) in real time during the whole fracturing construction process. 3 / min, the friction pressure drop gradient along the horizontal well fracturing construction that meets the current fracturing construction requirements obtained by the analysis method of the present invention is 0.68MPa / 100m, wherein the average sand-carrying fluid concentration in the current fracturing construction process is 21%.

[0057] Figure 6 This is a third example schematic diagram of the friction resistance and pressure drop gradient along the horizontal well fracturing construction in the method for analyzing the friction resistance of horizontal well multi-stage fracturing construction in an embodiment of the present application. Figure 6 The graph 6c shows the demand curve for the change of sand content in the fracturing construction of a horizontal well, the demand curve 6b for the change of fracturing fluid displacement, and the curve 6a showing the change of wellhead construction pressure data (before correction) in real time during the whole fracturing construction process. 3 / min, the friction pressure drop gradient along the horizontal well fracturing construction that meets the current fracturing construction requirements obtained by the analysis method of the present invention is 0.82MPa / 100m, wherein the average sand-carrying fluid concentration in the current fracturing construction process is 23%.

[0058] In this way, the above technical scheme simulates various influencing factors affecting the friction pressure drop along the way by calculating the difference between the wellhead construction pressure curve corresponding to the injection of fracturing fluid with different displacement and / or sand ratio content data and the total throttling pressure drop when the fracturing fluid reaches the target well section according to the manifold structure of the current wellbore, and performs linear regression analysis on the wellhead construction pressure correction curve under different pre-fluid displacement and / or different sand-carrying fluid combinations to obtain a friction analysis model for multi-stage fracturing construction of horizontal wells, so that the corresponding friction pressure drop gradient along the fracturing construction of horizontal wells can be directly obtained according to the sand ratio data of the sand-carrying fluid to be analyzed and / or the displacement of the fracturing fluid to be analyzed in the actual on-site needs.

[0059] Embodiment 2

[0060] Based on the friction analysis method for multi-stage fracturing construction of horizontal wells in embodiment 1, the present invention further proposes a friction analysis system for multi-stage fracturing construction of horizontal wells. Figure 7 Module block diagram of the system for analyzing friction resistance of multi-stage fracturing construction in horizontal wells according to an embodiment of the present application. Figure 7 As shown, the analysis system includes: a construction pressure curve drawing module 71, a construction pressure curve correction module 72 and a friction pressure drop determination module 73 along the way.

[0061] Among them, the construction pressure curve drawing module 71 is implemented according to the method described in the above step S110, and is configured to collect and count the fracturing construction data. Based on this, the wellhead construction pressure data under the effect of the injection pre-fluid displacement and / or the sand-carrying liquid-sand ratio change is recorded, and the corresponding curve of the wellhead construction pressure changing with the fracturing stage of different horizontal sections is drawn. The construction pressure curve correction module 72 is implemented according to the method described in the above step S120, and is configured to determine the throttling total pressure drop corresponding to the front section sliding sleeve passed by the fracturing fluid when it reaches the target well section sliding sleeve opening position according to the manifold structure data, and correct the wellhead construction pressure change curve according to the above throttling total pressure drop. Finally, the friction pressure drop determination module 73 along the way is implemented according to the method described in the above step S130, and is configured to perform regression analysis on the wellhead pressure correction curve obtained in step S120, and use the current analysis results, the sand-carrying liquid-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed, to obtain the friction pressure drop gradient along the horizontal well fracturing construction under the corresponding conditions.

[0062] Furthermore, the construction pressure curve correction module 72 includes: a construction distance determination unit 721, a total throttling pressure drop generation unit 722, a curve to be corrected generation unit 723 and a correction result generation unit 724. Among them, the construction distance determination unit 721 is configured to determine the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well. The total throttling pressure drop generation unit 722 is configured to filter out the inner diameter of each ball seat passed by the fracturing fluid when reaching the target well section sliding sleeve opening position from the above construction data, and the corresponding sliding sleeve throttling pressure drop when passing each ball seat, and calculate the total throttling pressure drop based on the current well section fracturing construction according to the distance (result) obtained by the construction distance determination unit 721. The curve generation unit 723 is configured to select the wellhead construction pressure data corresponding to the same displacement and / or sand ratio conditions during the entire fracturing construction process from the wellhead construction pressure change curve obtained by the construction pressure curve drawing module 71, and based on this, draw the construction pressure curve to be corrected under the current displacement and / or sand ratio combination conditions, and further obtain multiple construction pressure curves to be corrected under different displacement and / or sand ratio combination conditions. Finally, the correction result generation unit 724 is configured to correct each wellhead construction pressure data in the construction pressure to be corrected curve under each combination condition according to the throttling total pressure drop for the current well section fracturing construction obtained by the total throttling pressure drop generation unit 722, and obtain the corrected wellhead construction pressure data, based on which, draw the wellhead pressure correction curve for each combination condition.

[0063] Among them, the correction result generating unit 724 is further configured to perform a difference operation on each wellhead construction pressure data and the total throttling pressure drop under the fracturing construction of the corresponding well section to obtain the corresponding wellhead construction pressure correction data, based on which, a wellhead construction pressure correction curve is drawn.

[0064] Furthermore, the friction pressure drop determination module 73 along the process includes: an analysis result generation unit 731 and a friction pressure drop gradient generation unit 732 along the process. The analysis result generation unit 731 is configured to use the least square method to perform linear fitting analysis on the wellhead pressure correction curve based on the position in the wellhead pressure correction curve obtained by the correction result generation unit 724 that meets the current fracturing construction requirements and the corrected wellhead construction pressure data, and obtain the corresponding linear regression result. Then, the friction pressure drop gradient generation unit 732 along the process is configured to determine the sand ratio concentration data to be analyzed or the pre-fluid displacement to be analyzed that meets the current fracturing construction requirements, and based on this, according to the linear regression result obtained by the analysis result generation unit 731, the corresponding regression coefficient is determined to represent the friction pressure drop gradient along the horizontal well fracturing construction that meets the conditions to be analyzed.

[0065] The present invention relates to a method and system for analyzing friction resistance of multi-stage fracturing construction in horizontal wells. In view of the problem that the construction friction resistance cannot be accurately calculated at the existing horizontal well fracturing site, a simple and feasible method for analyzing and calculating fracturing construction friction resistance that can be widely applied to fracturing sites is provided, including the following processes: collecting and counting on-site construction data, drawing construction pressure change curves, correcting construction curves, and performing regression analysis of friction resistance and pressure drop data. The method provided by the present invention can simply, quickly, and accurately calculate the fracturing construction friction resistance and pressure drop of horizontal wells under different formation conditions at different sand ratios and different displacements, and can be promoted and applied at the fracturing site to provide guiding suggestions for the calculation of on-site fracturing construction pressure and fracture pressure, as well as the designation of fracturing construction plans and the optimization and adjustment of process plans.

[0066] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for analyzing friction resistance in multi-stage fracturing of horizontal wells, characterized in that: include: Step 1: Collect and compile statistics of fracturing construction data, based on which, record the wellhead construction pressure data under the influence of changes in injection pre-fluid displacement and / or sand-carrying liquid-sand ratio, and draw a curve of the corresponding wellhead construction pressure changing with the fracturing stage of different horizontal sections; Step 2: Determine the total throttling pressure drop corresponding to the front-stage sliding sleeve that the fracturing fluid passes through when reaching the sliding sleeve opening position of the target well section according to the manifold structure data, and correct the wellhead construction pressure change curve according to the total throttling pressure drop; Step 3: Perform regression analysis on the wellhead pressure correction curve. Using the analysis results, the friction pressure drop gradient along the horizontal well fracturing operation under corresponding conditions is obtained from the sand-carrying liquid-sand ratio data to be analyzed and / or the pre-fluid displacement to be analyzed, including: Based on the position in the wellhead pressure correction curve and the corrected wellhead operation pressure data, a least square method is used to perform a linear fitting analysis on the wellhead pressure correction curve to obtain a corresponding linear regression result; Determine the sand ratio data to be analyzed or the pre-fluid displacement to be analyzed that meets the current fracturing construction requirements, and based on this, determine the corresponding regression coefficient according to the linear regression result to represent the friction pressure drop gradient along the horizontal well fracturing construction that meets the conditions to be analyzed.

2. The method according to claim 1, characterized in that: In the step 2, Determine the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well; The inner diameter of each ball seat that the fracturing fluid passes through when reaching the sleeve opening position of the target well section, and the corresponding sleeve throttling pressure drop when passing through each ball seat are screened out from the construction data, and the total throttling pressure drop based on the fracturing construction of the current well section is calculated based on the distance.

3. The method according to claim 1 or 2, characterized in that: The second step comprises: The wellhead construction pressure data corresponding to the same displacement and / or sand ratio conditions during the entire fracturing construction process are screened out from the wellhead construction pressure change curve, and based on this, a construction pressure to be corrected curve under the current displacement and / or sand ratio combination conditions is drawn, and multiple construction pressure to be corrected curves under different displacement and / or sand ratio combination conditions are further obtained; According to the total throttling pressure drop, each wellhead construction pressure data in the construction pressure to be corrected curve under each combination condition is corrected, and according to the corrected wellhead construction pressure data, the wellhead pressure correction curve under each combination condition is drawn.

4. The method according to claim 3, characterized in that further, The difference calculation is performed between each wellhead construction pressure data and the total throttling pressure drop under the fracturing construction of the corresponding well section to obtain the corresponding wellhead construction pressure correction data, based on which the wellhead pressure correction curve is drawn.

5. A system for analyzing friction resistance of multi-stage fracturing in horizontal wells, characterized in that: include: A construction pressure curve drawing module collects and compiles statistics of fracturing construction data, based on which, records the wellhead construction pressure data under the influence of changes in injection pre-fluid displacement and / or sand-carrying liquid-sand ratio, and draws the corresponding curve of wellhead construction pressure changes with different horizontal sections of fracturing stages; A construction pressure curve correction module determines the total throttling pressure drop corresponding to the front-stage sliding sleeve that the fracturing fluid passes through when reaching the sliding sleeve opening position of the target well section according to the manifold structure data, and corrects the wellhead construction pressure change curve according to the total throttling pressure drop; The module for determining the friction pressure drop along the way performs regression analysis on the wellhead pressure correction curve, and uses the analysis result to obtain the friction pressure drop gradient along the way of horizontal well fracturing construction under corresponding conditions from the sand-carrying liquid-sand ratio data to be analyzed and / or the displacement of the pre-fluid to be analyzed, wherein the module for determining the friction pressure drop along the way includes: an analysis result generating unit, which performs a linear fitting analysis on the wellhead pressure correction curve using a least square method based on the position in the wellhead pressure correction curve and the corrected wellhead operation pressure data, and obtains a corresponding linear regression result; A friction resistance pressure drop gradient generating unit along the process determines the sand ratio data to be analyzed or the pre-fluid displacement to be analyzed that meets the current fracturing construction requirements, and based on this, determines the corresponding regression coefficient according to the linear regression result to represent the friction resistance pressure drop gradient along the horizontal well fracturing construction that meets the conditions to be analyzed.

6. The system according to claim 5, characterized in that The construction pressure curve correction module includes: A construction distance determination unit, which determines the distance from the well section position in the current well section fracturing construction to the starting position of the horizontal well; A total throttling pressure drop generating unit is configured to filter out from the construction data the inner diameter of each ball seat that the fracturing fluid passes through when reaching the sleeve opening position of the target well section, and the corresponding sleeve throttling pressure drop when passing through each ball seat, and calculate the total throttling pressure drop based on the fracturing construction of the current well section according to the distance.

7. The system according to claim 5 or 6, characterized in that: The construction pressure curve correction module further includes: A curve-to-be-corrected generating unit, which selects the wellhead construction pressure data corresponding to the same displacement and / or sand ratio conditions during the entire fracturing construction process from the wellhead construction pressure change curve, and based on this, draws a construction pressure curve to be corrected under the current displacement and / or sand ratio combination conditions, and further obtains multiple construction pressure curves to be corrected under different displacement and / or sand ratio combination conditions; A correction result generating unit corrects each wellhead construction pressure data in the construction pressure to be corrected curve under each combination condition according to the total throttling pressure drop, and draws the wellhead pressure correction curve under each combination condition according to the corrected wellhead construction pressure data.

8. The system according to claim 7, characterized in that The correction result generating unit further performs a difference operation on each wellhead construction pressure data and the total throttling pressure drop under the corresponding well section fracturing construction to obtain corresponding wellhead construction pressure correction data, based on which, the wellhead pressure correction curve is drawn.

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