CN113356823B - Crack initiation method, device, system and controller - Google Patents
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Abstract
Description
Translated fromChinese技术领域technical field
本申请涉及水力压裂技术领域，特别涉及一种裂缝的起裂方法、装置、系统及控制器。The present application relates to the technical field of hydraulic fracturing, in particular to a crack initiation method, device, system and controller.
背景技术Background technique
对于页岩、煤岩、致密砂岩等储层，由于其自身渗透率极低，因此无法形成有效的油气流动通道。想要高效开发这些储层，必须提高储层的渗透率，其中压裂技术是提高储层渗透率最常用且最有效的方法之一。对于渗透率极低的储层，往往需要通过压裂技术形成复杂缝网，进而才能形成有效的油气流动通道。For reservoirs such as shale, coal rock, and tight sandstone, due to their extremely low permeability, effective oil and gas flow channels cannot be formed. In order to develop these reservoirs efficiently, the permeability of the reservoir must be increased, and fracturing technology is one of the most common and effective methods to improve the permeability of the reservoir. For reservoirs with extremely low permeability, it is often necessary to form complex fracture networks through fracturing technology, so as to form effective oil and gas flow channels.
然而在高水平应力差的作用下，现有水力压裂技术并不能形成复杂缝网，这样将影响油气的流动，不利于进行高效开采。However, under the action of high level stress difference, the existing hydraulic fracturing technology cannot form a complex fracture network, which will affect the flow of oil and gas, and is not conducive to efficient production.
发明内容Contents of the invention
本申请实施方式的目的是提供一种裂缝的起裂方法、装置、系统及控制器，以提高开采效率。The purpose of the embodiments of the present application is to provide a fracture initiation method, device, system and controller to improve mining efficiency.
为解决上述技术问题，本说明书实施方式提供一种裂缝的起裂方法，所述方法包括：获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；所述缝口为所述目标裂缝的起裂点，所述缝尖为所述目标裂缝延伸方向上远离所述缝口的位置；当所述目标裂缝的缝尖被封堵，且缝口被封堵在与所述目标裂缝相交的裂缝中或与所述目标裂缝相交的井筒中时，控制脉冲泵在所述目标裂缝的缝口施加脉冲压力，使得所述目标裂缝延伸方向上的至少一个点起裂，其中，所述脉冲压力的频率为所述液柱的一个阶数的固有频率。In order to solve the above technical problems, the embodiment of this specification provides a crack initiation method, the method includes: obtaining the natural frequency of one order of the liquid column filled in the target crack from the opening to the tip of the crack; The opening is the initiation point of the target fracture, and the tip is the position away from the opening in the extension direction of the target crack; when the tip of the target fracture is blocked and the opening is blocked at When in a fracture intersecting with the target fracture or in a wellbore intersecting with the target fracture, control the pulse pump to apply pulse pressure on the opening of the target fracture, so that at least one point in the extension direction of the target fracture initiates a crack , wherein the frequency of the pulse pressure is a natural frequency of an order of the liquid column.
本说明书实施例还提供了一种裂缝的起裂装置，包括：获取模块，用于获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；所述缝口为所述目标裂缝的起裂点，所述缝尖为所述目标裂缝延伸方向上远离所述缝口的位置；控制模块，用于当所述目标裂缝的缝尖被封堵，且缝口被封堵在与所述目标裂缝相交的裂缝中或与所述目标裂缝相交的井筒中时，控制脉冲泵在所述目标裂缝的缝口施加脉冲压力，使得所述目标裂缝延伸方向上的至少一个点起裂，其中，所述脉冲压力的频率为所述液柱的一个阶数的固有频率。The embodiment of this specification also provides a crack initiation device for cracks, including: an acquisition module, used to acquire a natural frequency of one order of the liquid column filled in the target crack from the opening to the tip of the crack; the opening is The initiation point of the target fracture, the slit tip is a position away from the slit opening in the extension direction of the target crack; the control module is used for when the slit tip of the target crack is blocked and the slit opening is closed When plugging in a fracture intersecting with the target fracture or in a wellbore intersecting with the target fracture, control the pulse pump to apply pulse pressure on the opening of the target fracture, so that at least one of the target fracture extension directions Crack initiation, wherein the frequency of the pulse pressure is a natural frequency of an order of the liquid column.
本说明书实施例还提供了一种裂缝的起裂系统，包括：至少两个封隔器，用于将目标裂缝的缝口封堵在与所述目标裂缝相交的裂缝中或与所述目标裂缝相交的井筒中；控制器，用于获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；所述缝口为所述目标裂缝的起裂点，所述缝尖为所述目标裂缝延伸方向上远离所述缝口的位置；并控制脉冲泵产生预定频率的脉冲压力；所述脉冲泵，用于当所述目标裂缝的缝尖被封堵，且缝口被封堵在与所述目标裂缝相交的裂缝中或与所述目标裂缝相交的井筒中时，在所述目标裂缝的缝口施加脉冲压力，使得所述目标裂缝的延伸方向上的至少一个点起裂，其中，所述脉冲压力的频率为所述液柱的一个阶数的固有频率。The embodiment of this specification also provides a fracture initiation system, including: at least two packers, used to seal the opening of the target fracture in the fracture intersecting with the target fracture or with the target fracture In the intersecting wellbore; the controller is used to obtain the natural frequency of one order of the liquid column filled in the fracture tip from the fracture opening of the target fracture; the fracture opening is the crack initiation point of the target fracture, and the fracture opening is The tip is a position away from the slit opening in the extension direction of the target fracture; and the pulse pump is controlled to generate pulse pressure at a predetermined frequency; the pulse pump is used for when the slit tip of the target fracture is blocked and the slit When being plugged in a fracture intersecting with the target fracture or in a wellbore intersecting with the target fracture, a pulse pressure is applied to the opening of the target fracture so that at least one point in the extension direction of the target fracture Crack initiation, wherein the frequency of the pulse pressure is a natural frequency of an order of the liquid column.
本说明书实施例所提供的裂缝的起裂方法，改进了现有水力压裂方法，通过脉冲泵设备即可使目标裂缝延伸方向上的至少一个点起裂，相较于现有的爆炸起裂方式，起裂点的位置可控，并且便于形成复杂度较高的缝网，从而提高开采效率。The crack initiation method provided by the embodiment of this specification improves the existing hydraulic fracturing method, and at least one point in the extension direction of the target crack can be cracked by pulse pump equipment, compared with the existing explosive crack initiation method In this way, the position of the crack initiation point is controllable, and it is convenient to form a fracture network with high complexity, thereby improving the mining efficiency.
附图说明Description of drawings
为了更清楚地说明本申请实施方式或现有技术中的技术方案，下面将对实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请中记载的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some implementations described in this application. Those skilled in the art can also obtain other drawings based on these drawings without any creative work.
图1示出了示出了井筒的示意图；Figure 1 shows a schematic diagram showing a wellbore;
图2示出了井筒周围通过现有水力压裂技术形成的主缝的示意图；Figure 2 shows a schematic diagram of the main fracture formed by the existing hydraulic fracturing technology around the wellbore;
图3示出了通过本说明书实施例所提供的裂缝的起裂方法使主缝的一个裂缝翼起裂的方法示意图；Fig. 3 shows a schematic diagram of a method for cracking a crack wing of a main crack through the crack cracking method provided by the embodiment of this specification;
图4示出了根据本说明书实施例的裂缝的起裂方法的流程图；Fig. 4 shows a flow chart of a method for crack initiation according to an embodiment of the present specification;
图5示出了确定缝口所施加的脉冲循环压力的频率的方法流程图；Fig. 5 shows a flow chart of a method for determining the frequency of pulse cycle pressure applied by a slot;
图6A示出了缝口施加一阶固有频率的脉冲压力时，传导至裂缝延伸方向上岩石所受到的脉冲压力的幅值；Fig. 6A shows the amplitude of the pulse pressure transmitted to the rock in the direction of the fracture extension when the pulse pressure of the first order natural frequency is applied to the fracture opening;
图6B示出了缝口施加二阶固有频率的脉冲压力时，传导至裂缝延伸方向上岩石所受到的脉冲压力的幅值；Fig. 6B shows the amplitude of the pulse pressure transmitted to the rock in the direction of the fracture extension when the pulse pressure of the second-order natural frequency is applied to the fracture opening;
图6C示出了缝口施加三阶固有频率的脉冲压力时，传导至裂缝延伸方向上岩石所受到的脉冲压力的幅值；Figure 6C shows the amplitude of the pulse pressure transmitted to the rock in the direction of the fracture extension when the pulse pressure of the third-order natural frequency is applied to the fracture opening;
图7示出了获取裂缝的缝口至缝尖所填充的液柱的固有频率的方法流程图；Fig. 7 shows the flow chart of the method for obtaining the natural frequency of the liquid column filled from the opening of the fracture to the tip of the fracture;
图8A示出了根据本说明书实施例的一种裂缝的起裂装置的原理框图；Fig. 8A shows a functional block diagram of a crack initiation device according to an embodiment of the present specification;
图8B示出了根据本说明书实施例的另一种裂缝的起裂装置的原理框图；Fig. 8B shows a schematic block diagram of another crack initiation device according to an embodiment of the present specification;
图9示出了根据本说明书实施例的一种控制器的原理框图。Fig. 9 shows a functional block diagram of a controller according to an embodiment of the present specification.
具体实施方式Detailed ways
为了使本技术领域的人员更好地理解本申请中的技术方案，下面将结合本申请实施方式中的附图，对本申请实施方式中的技术方案进行清楚、完整地描述，显然，所描述的实施方式仅仅是本申请一部分实施方式，而不是全部的实施方式。基于本申请中的实施方式，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施方式，都应当属于本申请保护的范围。In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described The implementations are only some of the implementations of the present application, not all of them. Based on the implementation manners in this application, all other implementation manners obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.
如图1所示，水力压裂技术是指在石油、天然气等资源开采的过程中，从地面朝向地层深处打井之后，利用地面高压泵组，以超过地层吸收能力的排量将高粘液体(即压裂液)泵入井内，从而在井底憋起高压，当该压力克服井壁附近地应力达到岩石抗拉强度后，就在井底产生长直裂缝。As shown in Figure 1, hydraulic fracturing technology refers to the process of drilling oil, natural gas and other resources, after drilling wells from the ground to the depth of the formation, using the ground high-pressure pump group to pump high-viscosity fluid with a displacement exceeding the absorption capacity of the formation. The fluid (that is, fracturing fluid) is pumped into the well, so that high pressure is suppressed at the bottom of the well. When the pressure overcomes the stress near the well wall and reaches the tensile strength of the rock, long straight fractures will be generated at the bottom of the well.
水力压裂技术利用液体传递压力在地层岩石中形成人工裂缝时，裂缝总是沿着最有利的方向扩展和传播，一般的情况下裂缝沿垂直于最小水平地应力的方向扩展，形成关于井筒两个对称的裂缝翼。由于最小水平地应力一般都是水平方向，因此裂缝一般是垂直缝，图2示出了图1中A框中所示部分井筒周围的裂缝细节。上述长直裂缝即为本说明书中所述的主缝。When hydraulic fracturing technology uses liquid to transmit pressure to form artificial fractures in formation rocks, the fractures always expand and propagate along the most favorable direction. Generally, the fractures expand along the direction perpendicular to the minimum horizontal ground stress, forming the two sides of the wellbore. A symmetrical slit wing. Since the minimum horizontal in-situ stress is generally horizontal, the fractures are generally vertical. Fig. 2 shows the details of the fractures around the part of the wellbore shown in box A in Fig. 1. The above-mentioned long straight cracks are the main cracks described in this manual.
图1所示的井筒在竖直筒(即沿竖直方向延伸的井筒)的基础上叠加水平筒(即沿水平方向延伸的井筒)。实际上，井筒也可以仅为竖直筒。当图2中两个方向上的水平地应力相等时，主缝的方向就很难确定。In the shaft shown in Fig. 1, a horizontal shaft (ie, a shaft extending in a horizontal direction) is superimposed on the basis of a vertical shaft (ie, a shaft extending in a vertical direction). In fact, the shaft can also be just a vertical shaft. When the horizontal stresses in the two directions in Fig. 2 are equal, it is difficult to determine the direction of the main seam.
在上述现有水力压裂技术的基础上，发明人通过瞬变流模型和特征线法，模拟了在主缝缝口施加脉冲循环压力时，主缝延伸方向上的压力分布规律。On the basis of the above-mentioned existing hydraulic fracturing technology, the inventor simulated the pressure distribution law in the extension direction of the main fracture when the pulse cycle pressure is applied to the opening of the main fracture through the transient flow model and the characteristic line method.
结果显示，主缝中延伸方向上各位置点的岩石所受到的压力仍是脉冲压力，各位置点压力频率与缝口所施加的脉冲循环压力的频率一致；当所施加的脉冲循环压力的频率确定时，传导至主缝延伸方向上的各位置点的岩石所受到的脉冲压力幅值是非均质分布的，传导至岩石上一个位置点脉冲压力的幅值由该位置点到缝口或缝尖的距离决定；在缝口施加不同频率的脉冲循环压力时，传导至岩石上各位置点的脉冲压力幅值分布也不同。The results show that the pressure on the rock at each point in the extension direction of the main fracture is still pulse pressure, and the frequency of the pressure at each point is consistent with the frequency of the pulse cycle pressure applied to the fracture opening; when the frequency of the applied pulse cycle pressure is determined When , the amplitude of the pulse pressure transmitted to the rock at each point in the extension direction of the main fracture is heterogeneously distributed, and the amplitude of the pulse pressure transmitted to a point on the rock is from the point to the opening or tip of the fracture. The distance is determined by the distance; when the pulse cycle pressure of different frequencies is applied to the fracture, the amplitude distribution of the pulse pressure transmitted to each point on the rock is also different.
具体地，如图6A、图6B和图6C所示，不同频率下传导至岩石上各位置点的脉冲压力幅值分布有以下规律：沿主缝延伸方向存在脉冲压力幅值的极大值点，这些极大值点的个数与所施加脉冲循环压力的频率有关，当缝口所施加的脉冲循环压力的频率在液柱的一阶固有频率附近时，沿主缝延伸方向存在一个脉冲压力幅值的极大值点，当缝口所施加的脉冲循环压力的频率在液柱的二阶固有频率附近时，沿主缝延伸方向存在两个脉冲压力幅值的极大值点。本说明书中的极大值点是指目标裂缝延伸方向上的位置，且在该位置点处岩石所受到的脉冲压力幅值为极大值。Specifically, as shown in Fig. 6A, Fig. 6B and Fig. 6C, the distribution of pulse pressure amplitude transmitted to various points on the rock at different frequencies has the following rules: there is a maximum point of pulse pressure amplitude along the extension direction of the main fracture , the number of these maximum points is related to the frequency of the applied pulse cycle pressure. When the frequency of the pulse cycle pressure applied to the seam is near the first-order natural frequency of the liquid column, there is a pulse pressure along the direction of the main seam extension The maximum point of the amplitude, when the frequency of the pulse cycle pressure applied by the gap is near the second-order natural frequency of the liquid column, there are two maximum points of the amplitude of the pulse pressure along the extension direction of the main fracture. The maximum value point in this specification refers to the position in the extension direction of the target fracture, and the amplitude of the pulse pressure on the rock at this point is the maximum value.
例如，主缝长度200m，当缝口施加脉冲压力P时，比如P＝10(sin(fin×2πt))+10，单位MPa，fin为所施加的脉冲循环压力的频率，裂缝粗糙度为0.001m，主缝中的液柱第5阶固有频率为16.65Hz在该输入频率下，距离缝口的20m，70m，120m，160m，200m位置点处岩石所受到的脉冲压力幅值出现极大值。由岩石疲劳力学可知，高幅值下岩石的疲劳寿命远小于低幅值时。由此，可以得知主缝中这些幅值的极大值点将会率先起裂，合适的频率下主缝中存在多个极大值点，也就意味着存在多个新裂缝起裂点。For example, the length of the main fracture is 200m, when the pulse pressure P is applied to the fracture opening, such as P=10(sin(fin ×2πt))+10, the unit is MPa,fin is the frequency of the applied pulse cycle pressure, and the fracture roughness is 0.001m, and the fifth-order natural frequency of the liquid column in the main fracture is 16.65Hz. Under this input frequency, the amplitude of the pulse pressure on the rock at the positions of 20m, 70m, 120m, 160m, and 200m from the fracture mouth appears extremely big value. According to rock fatigue mechanics, the fatigue life of rock under high amplitude is much smaller than that under low amplitude. From this, it can be known that the maximum points of these amplitudes in the main fracture will be the first to initiate cracks, and there are multiple maximum points in the main fracture at a suitable frequency, which means that there are multiple new crack initiation points .
本说明书中的极大值是指，在裂缝延伸方向上，如果一个位置点的周围各位置点处岩石所受到的脉冲压力幅值都小于该位置点处岩石所受到的脉冲压力幅值，则该位置点为极大值点。在确定极大值时，距离缝口0m位置点处岩石所受到的脉冲压力幅值被排除在极大值之外，在缝尖的远离缝口一侧的位置点处岩石所受到的脉冲压力幅值为0，如图6A至图6C所示。The maximum value in this specification means that in the direction of fracture extension, if the pulse pressure amplitudes of the rocks at all points around a point are smaller than the pulse pressure amplitudes of the rocks at this point, then This position point is the maximum value point. When determining the maximum value, the amplitude of the pulse pressure on the rock at the point 0m away from the fracture opening is excluded from the maximum value, and the pulse pressure on the rock at the point on the side of the fracture tip far away from the fracture opening The amplitude is 0, as shown in Figures 6A to 6C.
基于以上发现，发明人提出了一种裂缝的起裂方法，该方法可以用于使一条裂缝延伸方向上的多点起裂，进而形成复杂缝网。如图4所示，该方法包括如下步骤。Based on the above findings, the inventors proposed a fracture initiation method, which can be used to initiate multiple points along the extension direction of a fracture, thereby forming a complex fracture network. As shown in Figure 4, the method includes the following steps.
S10：获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；该缝口为目标裂缝的起裂点，缝尖为目标裂缝延伸方向上远离缝口的位置。S10: Obtain the natural frequency of one order of the liquid column filled in the crack opening to the tip of the target fracture; the crack opening is the crack initiation point of the target fracture, and the crack tip is a position away from the crack opening in the extension direction of the target fracture.
步骤S10中的目标裂缝即待裂缝的起裂的裂缝，目标裂缝可以是现有水力压裂所形成的长直裂缝。例如，控制高压泵组向井筒中泵入压裂液，使得井底形成高压而在井筒周围产生至少一条长直裂缝，该长直裂缝也可以称为主缝。步骤S10中的裂缝即可以为其中一条主缝，即图2或图3中所示的主缝，此时缝口即为主缝与井筒的相交处，缝尖为主缝延伸方向上远离井筒的位置。The target fracture in step S10 is the fracture to be fractured, and the target fracture may be a long straight fracture formed by existing hydraulic fracturing. For example, the high-pressure pump group is controlled to pump fracturing fluid into the wellbore, so that a high pressure is formed at the bottom of the wellbore to generate at least one long straight fracture around the wellbore, and the long straight fracture can also be called a main fracture. The fracture in step S10 can be one of the main fractures, that is, the main fracture shown in Figure 2 or Figure 3. At this time, the fracture opening is the intersection of the main fracture and the wellbore, and the fracture tip is far away from the wellbore in the extension direction of the main fracture. s position.
在一些实施例中，使得主缝延伸方向上的一个点起裂，起裂点处延伸出至少一条子裂缝，步骤S10中的目标裂缝也可以是其中一条子裂缝。In some embodiments, a point along the extension direction of the main crack is made to initiate a crack, and at least one sub-crack extends from the crack initiation point, and the target crack in step S10 may also be one of the sub-cracks.
地层中的裂缝通常是通过各种水力压裂的技术形成的，因此在裂缝的缝口至缝尖中会填充有压裂液形成一段液柱。可以将该液柱视为物体，研究缝口处所施加的脉冲循环压力在裂缝延伸方向上的传播情况，也即研究机械波的传播情况。由振动力学知识，具有一定边界条件的物体，当物体受到初始扰动后会呈现自由振动，即其位移随时间按正弦或余弦规律变化。自由振动的频率与初始条件无关，而仅与物体的固有特性(如质量、性质、材质)有关，因此也称为固有频率。一个物体的固有频率可以有多个。Fractures in the formation are usually formed by various hydraulic fracturing techniques, so the fracturing fluid will be filled from the opening to the tip of the fracture to form a liquid column. The liquid column can be regarded as an object, and the propagation of the pulse cycle pressure applied at the fracture opening in the direction of fracture extension can be studied, that is, the propagation of mechanical waves can be studied. According to the knowledge of vibration mechanics, an object with certain boundary conditions will exhibit free vibration when the object is initially disturbed, that is, its displacement changes with time according to the law of sine or cosine. The frequency of free vibration has nothing to do with the initial conditions, but only with the inherent characteristics of the object (such as mass, nature, material), so it is also called the natural frequency. An object can have multiple natural frequencies.
步骤S10可以仅获取液柱的一个阶数的固有频率，也可以获取多个阶数的固有频率，如一阶固有频率、二阶固有频率、三阶固有频率等。In step S10, the natural frequency of only one order of the liquid column may be obtained, or the natural frequency of multiple orders may be obtained, such as the first-order natural frequency, the second-order natural frequency, the third-order natural frequency, and the like.
S20：当目标裂缝的缝尖被封堵，且缝口被封堵在与目标裂缝相交的裂缝中或与目标裂缝相交的井筒中时，控制脉冲泵在目标裂缝的缝口施加脉冲压力，使得目标裂缝延伸方向上的至少一个点起裂，其中，脉冲压力的频率为液柱的一个阶数的固有频率。S20: When the tip of the target fracture is blocked and the opening is blocked in the fracture intersecting the target fracture or in the wellbore intersecting the target fracture, control the pulse pump to apply pulse pressure on the opening of the target fracture, so that At least one point along the extension direction of the target fracture initiates, wherein the frequency of the pulse pressure is a natural frequency of an order of the liquid column.
如图3所示出，B为脉冲泵，C为封隔器，图3中分别设置在脉冲泵B两侧的两个封隔器将脉冲泵B封隔在一段井筒中。D所指示的原点表示暂堵剂，通过暂堵剂将缝尖封堵，暂堵剂可以是能够在目标裂缝的延伸方向上至少一个点起裂后降解或溶解的物质。As shown in Fig. 3, B is the pulse pump, and C is the packer. In Fig. 3, two packers respectively arranged on both sides of the pulse pump B seal the pulse pump B in a section of the wellbore. The origin indicated by D represents the temporary plugging agent, and the fracture tip is blocked by the temporary plugging agent. The temporary plugging agent can be a substance that can degrade or dissolve after cracking at least one point in the extension direction of the target fracture.
图3仅示出了缝口被封堵在与目标裂缝相交的井筒中的示意图。本说明书所提供的技术方案还适用于将缝口封堵在与目标裂缝相交的裂缝中。例如，在一些实施例中，使得主缝延伸方向上的一个点起裂，起裂点处延伸出至少一条子裂缝，当需要对子裂缝进一步起裂时，子裂缝即为目标裂缝，可以将子裂缝的缝口封堵在主缝中。Fig. 3 only shows a schematic diagram of the fracture opening being plugged in the wellbore intersecting the target fracture. The technical scheme provided by this specification is also applicable to sealing the seam in the fracture intersecting with the target fracture. For example, in some embodiments, a point in the extension direction of the main crack is cracked, and at least one sub-crack is extended from the crack initiation point. When the sub-crack needs to be further cracked, the sub-crack is the target crack. The opening of the sub-crack is blocked in the main crack.
现有的脉冲泵通常只能够朝向一个方向施加脉冲压力，因此，如图3所示，对于具有两个对称裂缝翼的裂缝，可以先控制脉冲泵在缝口朝向一个裂缝翼施加脉冲压力，使得这个裂缝翼上至少一个点起裂；然后在朝向另一个裂缝翼施加脉冲压力，使得另一个裂缝翼上至少一个点起裂。Existing pulse pumps can usually only apply pulse pressure in one direction. Therefore, as shown in Figure 3, for a fracture with two symmetrical crack wings, the pulse pump can be controlled to apply pulse pressure toward one crack wing at the crack opening, so that Crack initiation at least one point on the crack wing; and then applying pulsed pressure toward the other crack wing, causing at least one point crack initiation on the other crack wing.
在一些实施例中，脉冲泵可以朝向两个或多个方向施加脉冲压力，此时可以在缝口朝向两个裂缝翼同时施加脉冲压力，从而使这两个裂缝翼上的点起裂。In some embodiments, the pulse pump can apply pulse pressure in two or more directions. At this time, the pulse pressure can be applied simultaneously when the slit is facing two crack wings, so as to initiate cracks at points on the two crack wings.
在一些实施例中，目标裂缝的缝口延伸出多条裂缝翼，当脉冲泵可以朝向多个方向施加脉冲压力时，还可以在缝口朝向多条裂缝翼同时施加压力，从而使这些裂缝翼上的点起裂。In some embodiments, multiple crack wings are extended from the opening of the target crack. When the pulse pump can apply pulse pressure in multiple directions, it is also possible to apply pressure to the multiple crack wings at the same time, so that these crack wings The point above cracks.
在一些实施例中，除了用暂堵剂将缝尖堵住外，也可能实现地层中自然存在的致密物质将缝尖堵住。In some embodiments, in addition to plugging the fracture tip with a temporary plugging agent, it is also possible to block the fracture tip with naturally occurring tight substances in the formation.
根据发明人的发现，如图6A、图6B和图6C所示，当在缝口施加液柱的N阶固有频率时，传导至裂缝延伸方向上就会有N个脉冲压力幅值的极大值点，当所施加的脉冲压力幅值足够大使得传导至极大值点处的压力幅值达到岩石抗拉强度后便可以使N-1个(因为其中一个极大值点为缝尖位置，而缝尖位置被封堵了，从而无法根据岩石抗拉强度使缝尖处起裂)极大值点附近起裂，从而使目标裂缝上的多个点起裂。通过同样的方法使多条裂缝上的点起裂即可形成复杂缝网。According to the inventor's discovery, as shown in Fig. 6A, Fig. 6B and Fig. 6C, when the N-order natural frequency of the liquid column is applied to the fracture opening, there will be N pulse pressure amplitude maxima in the direction of fracture extension. value points, when the amplitude of the applied pulse pressure is large enough to make the pressure amplitude transmitted to the maximum point reach the tensile strength of the rock, N-1 (because one of the maximum point is the fracture tip position, and The position of the fracture tip is blocked, so it is impossible to initiate cracks near the maximum point at the fracture tip according to the tensile strength of the rock, so that multiple points on the target fracture can be cracked. A complex fracture network can be formed by initiating point fractures on multiple fractures by the same method.
例如，当所施加的脉冲压力幅值传导至目标裂缝延伸方向上各位置点后使得各位置点处岩石所受到的脉冲压力幅值如图6C所示时，假设各位置点处岩石抗张压力如图中虚线所示，则从图中可以看出，距离缝口0-62m(0m除外)、100-135m、170-200m(200m除外)的位置中的任一点均可能起裂。For example, when the applied pulse pressure amplitude is transmitted to each position point in the extension direction of the target fracture so that the pulse pressure amplitude experienced by the rock at each position point is shown in Figure 6C, it is assumed that the rock tensile pressure at each position point is as follows: As shown by the dotted line in the figure, it can be seen from the figure that any point in the position of 0-62m (except 0m), 100-135m, 170-200m (except 200m) from the crack may initiate cracks.
当压力过大时，在目标裂缝延伸方向上的一段距离内(例如0-62m)形成裂缝通常由于岩石拉伸破坏，而拉伸破坏的特点是形成一个起裂点并沿着该起裂点进一步开裂形成一条缝，从而无法在目标裂缝延伸方向上形成多个起裂点。然而，本说明书所提供的方法控制所施加的脉冲压力的幅值不至于过大，在目标裂缝延伸方向上的一段距离内(例如0-62m)使得岩石由于疲劳破坏而形成起裂点，疲劳破坏的特点是不同位置点的岩石抗张压力不同(图6C假设了不同位置点的岩石抗张压力相同)且多次脉冲压力冲击会使得一段距离内的任意一点均有起裂的可能。由此可见，当施加三阶脉冲循环压力时，在目标裂缝延伸方向上起裂的点数可能为任意自然数，这是无法确定的。When the pressure is too high, the formation of cracks within a certain distance (such as 0-62m) in the extension direction of the target crack is usually due to the tensile failure of the rock, and the characteristic of tensile failure is the formation of a crack initiation point and along the crack initiation point. Further cracking forms a seam, so that multiple crack initiation points cannot be formed in the direction of the target crack extension. However, the method provided in this specification controls the amplitude of the applied pulse pressure so that it will not be too large, so that within a certain distance (for example, 0-62m) in the extension direction of the target crack, the rock will form a crack initiation point due to fatigue damage, and fatigue The characteristic of failure is that the tensile pressure of rocks at different positions is different (Figure 6C assumes that the tensile pressures of rocks at different positions are the same), and multiple pulse pressure shocks will make any point within a certain distance have the possibility of cracking. It can be seen that when the third-order pulse cycle pressure is applied, the number of crack initiation points in the target fracture extension direction may be any natural number, which cannot be determined.
由上述可知，若使得各极大值点起裂，除了对所施加的脉冲循环压力的频率有要求之外，还需要脉冲循环压力的幅值足以使极大值点起裂又不能过大。It can be seen from the above that, if each maximum point is cracked, in addition to the frequency of the applied pulse cycle pressure, the amplitude of the pulse cycle pressure is also required to be sufficient to make the maximum point crack without being too large.
对此，本说明书实施例所提供的方法为：获取产生目标裂缝时在目录裂缝的缝口处监测到的破裂压力；将破裂压力与预定系数的乘积作为所施加的脉冲压力的幅值。In this regard, the method provided by the embodiment of this specification is: obtaining the rupture pressure monitored at the opening of the catalog fracture when the target fracture is generated; taking the product of the rupture pressure and a predetermined coefficient as the amplitude of the applied pulse pressure.
例如，以目标裂缝为主缝，将压裂液泵入井筒使得井底产生主缝时，监测到该主缝裂口处的破裂压力为Pc，则在该主缝的缝口施加脉冲循环压力使该主缝裂缝的起裂时，所施加的脉冲压力的幅值为αPc，其中α为一个系数。发明人进一步研究发现，该系数为1.2％至1.5％中任意数值时，多点起裂的效果较好。例如α可以为1.2％、1.3％、1.4％、1.5％。For example, when the target fracture is the main fracture, when the fracturing fluid is pumped into the wellbore to generate the main fracture at the bottom of the well, the fracture pressure at the opening of the main fracture is monitored to be Pc , and the pulse cycle pressure is applied to the opening of the main fracture When the main fracture is initiated, the amplitude of the applied pulse pressure is αPc , where α is a coefficient. The inventors have further studied and found that when the coefficient is any value between 1.2% and 1.5%, the effect of multi-point crack initiation is better. For example, α may be 1.2%, 1.3%, 1.4%, or 1.5%.
需要说明的是，破裂压力是在现场采用传感器等手段所监测到的地层中岩石破裂时所承受的实际压力。当无法通过该手段获取破裂压力时，也可以采用实验的方式获得岩石抗拉强度，将岩石抗拉强度的数值作为破裂压力的取值。采用实验的方式获得岩石抗拉强度的方法，例如可以为：在钻井的过程中，取出地层中的一块岩石作为样本，在实验室条件下测量该岩石样本的抗拉强度，从而获得该岩石样本所在的地层区域中岩石的抗拉强度。It should be noted that the fracture pressure is the actual pressure that the rock in the formation is subjected to when it breaks and is monitored by sensors and other means on site. When the fracture pressure cannot be obtained by this method, the tensile strength of the rock can also be obtained experimentally, and the value of the tensile strength of the rock can be used as the value of the fracture pressure. The method of obtaining the tensile strength of rock by experiment can be, for example, as follows: during the drilling process, a piece of rock in the formation is taken as a sample, and the tensile strength of the rock sample is measured under laboratory conditions, thereby obtaining the rock sample The tensile strength of the rock in the formation zone where it is located.
相应地，当认为实验室条件下所测得的岩石抗拉强度不准确，或者测得的数据适用性不好时，也可以在现场采用传感器等手段监测得到地层中岩石破裂时所承受的实际压力，并将该实际压力的数值作为岩石抗拉强度的取值。Correspondingly, when it is considered that the rock tensile strength measured under laboratory conditions is inaccurate, or the applicability of the measured data is not good, it is also possible to use sensors and other means to monitor the actual strength of the rock in the formation when it breaks. pressure, and take the value of the actual pressure as the value of rock tensile strength.
上述裂缝的起裂方法，改进了现有水力压裂方法，通过脉冲泵设备即可使目标裂缝延伸方向上的至少一个点起裂，相较于现有的爆炸起裂方式，起裂点的位置可控，并且便于形成复杂度较高的缝网，从而提高开采效率。The crack initiation method above improves the existing hydraulic fracturing method, and at least one point in the extension direction of the target crack can be cracked by the pulse pump equipment. Compared with the existing explosive crack initiation method, the crack initiation point The position is controllable, and it is convenient to form a fracture network with high complexity, so as to improve the mining efficiency.
在一些实施例中，步骤S10可以任意选取液柱的一个阶数的固有频率，只要使得目标裂缝能够进一步起裂即可。In some embodiments, step S10 may arbitrarily select a natural frequency of an order of the liquid column, as long as the target fracture can be further initiated.
在一些实施例中，预先设定好了目标裂缝延伸方向上需要起裂的大致位置，该大致位置可以为连续的一段距离，或者可以是如图6C所示的三段距离，或者钻井现场实际情况限定了需要起裂的大致位置(例如某段距离内具有特殊物质而不应该在该段距离内起裂)，此时，如图5所示，可以通过如下方法确定所施加的脉冲循环压力的频率。In some embodiments, the approximate position where the crack needs to be initiated in the extension direction of the target fracture is preset, and the approximate position can be a continuous distance, or can be three distances as shown in Figure 6C, or the actual position of the drilling site. The situation limits the approximate location where crack initiation is required (for example, there are special substances within a certain distance and crack initiation should not occur within this distance), at this time, as shown in Figure 5, the applied pulse cycle pressure can be determined by the following method Frequency of.
S30：获取向目标裂缝的缝口施加各阶数的固有频率的脉冲压力时，在目标裂缝延伸方向上岩石所受到的脉冲压力幅值的变化趋势。S30: Obtain the variation trend of the pulse pressure amplitude received by the rock in the extension direction of the target fracture when the pulse pressure of each order of natural frequency is applied to the opening of the target fracture.
S40：根据该变化趋势，确定脉冲压力幅值中的极大值的位置和/或极大值的个数。S40: According to the variation trend, determine the position of the maximum value and/or the number of maximum values in the pulse pressure amplitude.
S50：根据极大值的位置和/或极大值的个数，选取一个阶数的固有频率。S50: Select a natural frequency of an order according to the position of the maximum value and/or the number of the maximum value.
步骤S30中获取目标裂缝在延伸方向上岩石所受到的脉冲压力幅值的变化趋势时，可以采用实际采集脉冲压力幅值的方式，或者可以采用公式计算的方式。实际采集的方式可以为：在岩石表面设置压力传感器，在施加脉冲循环压力时，从缝口位置沿目标裂缝的延伸方向逐渐移动只缝尖位置，每隔预定距离采集一次脉冲压力幅值，从而得到变化趋势。公式计算的方式可以为：以液柱作为物体，利用瞬变流模型及特征线解法，推导出脉冲压力幅值的计算公式(公式具体推导过程详见后文)，每隔预定距离计算一次脉冲压力幅值，从而得到变化趋势。In step S30, when obtaining the variation trend of the pulse pressure amplitude experienced by the rock in the extension direction of the target fracture, the method of actually collecting the pulse pressure amplitude may be used, or the method of formula calculation may be used. The actual acquisition method can be as follows: a pressure sensor is installed on the rock surface, and when the pulse cycle pressure is applied, the position of the fracture mouth is gradually moved along the extension direction of the target fracture to the position of the fracture tip, and the pulse pressure amplitude is collected every predetermined distance, so that Get the trend of change. The calculation method of the formula can be as follows: take the liquid column as the object, use the transient flow model and the solution of the characteristic line to derive the calculation formula of the pulse pressure amplitude (see the following for the specific derivation process of the formula), and calculate the pulse every predetermined distance Pressure amplitude, so as to get the trend of change.
在上述两种方法中，相隔的预定距离取值可以很小很小，不限逼近于0，从而能够较为精确地得出极大值点的位置。本说明书中的极大值是指，在裂缝延伸方向上，如果一个位置点的周围各位置点处岩石所受到的脉冲压力幅值都小于该位置点处岩石所受到的脉冲压力幅值，则该位置点为极大值点。在确定极大值时，距离缝口0m位置点处岩石所受到的脉冲压力幅值被排除在极大值之外，在缝尖的远离缝口一侧的位置点处岩石所受到脉冲压力幅值为0，如图6A至图6C所示。In the above two methods, the value of the predetermined distance apart can be very small, not limited to approaching 0, so that the position of the maximum point can be obtained more accurately. The maximum value in this specification means that in the direction of fracture extension, if the pulse pressure amplitudes of the rocks at all points around a point are smaller than the pulse pressure amplitudes of the rocks at this point, then This position point is the maximum value point. When determining the maximum value, the pulse pressure amplitude experienced by the rock at the position 0m away from the fracture opening is excluded from the maximum value, and the pulse pressure amplitude experienced by the rock at the position far from the fracture opening is The value is 0, as shown in Figure 6A to Figure 6C.
例如，目标裂缝的长度为200m，裂缝内液柱的一阶固有频率为1.85Hz，二阶固有频率为5.55Hz，三阶固有频率为9.25Hz，计算求得裂缝延伸方向上各位置点处岩石所受到的脉冲压力幅值如图6A、图6B、图6C所示(图中相邻数据点的横坐标间隔仅为示意，并不代表实际情形)，其中，横轴表示裂缝延伸方向上的位置点与缝口的距离，纵轴表示传导至位置点处的岩石上的脉冲压力的幅值。从图中可以看出施加三阶固有频率的脉冲压力时，裂缝延伸方向上各位置点处岩石所受到的脉冲压力幅值的非均质性最强，除缝口位置外，有3个脉冲压力幅值的极大值点。根据图6A至图6C，当需要在距离缝口100m内的位置点处起裂时，可以选择施加二阶固有频率，当需要在裂缝延伸方向上的3段位置起裂时可以选择施加三阶固有频率。For example, the length of the target fracture is 200m, the first-order natural frequency of the liquid column in the fracture is 1.85Hz, the second-order natural frequency is 5.55Hz, and the third-order natural frequency is 9.25Hz. The received pulse pressure amplitudes are shown in Fig. 6A, Fig. 6B, and Fig. 6C (the abscissa interval between adjacent data points in the figure is only for illustration and does not represent the actual situation), where the abscissa represents the fracture extension direction The distance between the location point and the fracture opening, and the vertical axis represents the amplitude of the pulse pressure transmitted to the rock at the location point. It can be seen from the figure that when the pulse pressure of the third-order natural frequency is applied, the amplitude of the pulse pressure on the rock at each position in the direction of the fracture extension has the strongest heterogeneity. Except for the position of the fracture mouth, there are three pulse pressure The maximum point of the pressure amplitude. According to Figure 6A to Figure 6C, when it is necessary to initiate cracks at a point within 100m from the crack, you can choose to apply the second-order natural frequency, and when you need to initiate cracks at three positions in the crack extension direction, you can choose to apply the third-order Natural frequency.
上述步骤S30所施加的脉冲压力的幅值应当是较小而不足以使得目标裂缝延伸方向上任意一点起裂的。由于岩石抗张压力是未知的，因此执行步骤S30时选取脉冲压力幅值时往往从一个较小值开始尝试。由于脉冲压力幅值与岩石抗张压力相差较大时，目标裂缝延伸方向上脉冲压力幅值的变化趋势有所不同，因此，步骤S40所确定的变化趋势应当尽可能与步骤S20所施加的脉冲压力幅值形成的变化趋势相同。为此，上述确定所施加的脉冲循环压力的频率的方法还包括以下步骤：确定各极大值的取值；当极大值中取值最大者的取值小于岩石抗拉强度的预定比例时，增大所施加的脉冲压力的幅值，重新确定目标裂缝在延伸方向上岩石所受到的脉冲压力幅值的变化趋势，即重新执行步骤S30至S50。The amplitude of the pulse pressure applied in the above step S30 should be small enough to cause crack initiation at any point along the extension direction of the target fracture. Since the tensile pressure of the rock is unknown, when performing step S30 to select the pulse pressure amplitude, it is often tried from a smaller value. Since the variation trend of the pulse pressure amplitude in the target fracture extension direction is different when the difference between the pulse pressure amplitude and the rock tensile pressure is large, the variation trend determined in step S40 should be as close as possible to the pulse pressure applied in step S20. The change trend of pressure amplitude formation is the same. For this reason, the method for determining the frequency of the applied pulse cycle pressure also includes the following steps: determining the value of each maximum value; , increasing the amplitude of the applied pulse pressure, re-determining the change trend of the pulse pressure amplitude of the target fracture in the extension direction, that is, re-executing steps S30 to S50.
步骤S10获取固有频率的方法，可以通过试验的方式，也可以通过公式计算的方式。试验的方法，例如可以为：在缝口施加不同频率的脉冲循环压力，当液柱达到共振状态时，对应的脉冲循环压力的频率即为固有频率。公式计算的方法即利用瞬变流模型及特征线解法，推导出固有频率的计算公式(公式具体推导过程详见后文)。The method for obtaining the natural frequency in step S10 may be through experiments or formula calculations. The test method, for example, may be: apply pulse cycle pressures of different frequencies to the slit, and when the liquid column reaches a resonance state, the frequency of the corresponding pulse cycle pressure is the natural frequency. The formula calculation method is to use the transient flow model and the characteristic line solution method to derive the calculation formula of the natural frequency (see the following for the specific derivation process of the formula).
图7示出了通过公式计算的方式获取固有频率的方法。该方法包括如下步骤。Fig. 7 shows a method for obtaining the natural frequency through formula calculation. The method includes the following steps.
S60：获取目标裂缝的缝口至缝尖内所填充的压裂液的密度和弹性模量。S60: Obtain the density and elastic modulus of the fracturing fluid filled in the target fracture from the fracture opening to the fracture tip.
S70：获取目标裂缝的长度。S70: Obtain the length of the target crack.
S80：根据以下公式计算固有频率：
下面介绍固有频率计算公式的推导过程。The following describes the derivation process of the natural frequency calculation formula.
此处将裂缝中的液柱视为物体，利用波动方程的知识，来计算物体受到初始扰动后自由振动的频率，既固有频率。由波动方程：Here, the liquid column in the crack is regarded as an object, and the knowledge of the wave equation is used to calculate the frequency of free vibration of the object after the initial disturbance, that is, the natural frequency. From the wave equation:
其中Pt表示t时刻压力，a表示波速，t，x分别表示时间和位置，公式(1)的复数解为：where Pt represents pressure at time t, a represents wave velocity, t and x represent time and position respectively, and the complex solution of formula (1) is:
其中Pt*表示波动方程中压力的复数解，A*，B*表示复数常数，由边界条件获得，e为自然对数的底，ω脉动圆频率。where Pt* represents the complex solution of the pressure in the wave equation, A*, B* represent the complex constants obtained from the boundary conditions, e is the base of the natural logarithm, and ω pulsation circular frequency.
其中
其中
由(2)和(5)可得到两个截面的压力和速度之间应满足下式：From (2) and (5), it can be obtained that the pressure and velocity of the two sections should satisfy the following formula:
求解得：Solved:
其中n为自然数，则泵注边界为压力边界时，液柱的固有频率为：Where n is a natural number, when the pump injection boundary is the pressure boundary, the natural frequency of the liquid column is:
上式中，n为自然数，fn+1代表其1、2、3、4…阶固有频率；l代表裂缝长度；a为脉冲压力波传播速度，其表达式为：In the above formula, n is a natural number, fn+1 represents its 1st, 2nd, 3rd, 4th order natural frequency; l represents the fracture length; a is the pulse pressure wave propagation velocity, and its expression is:
上式中K代表压裂液弹性模量；ρ代表压裂液密度；E代表岩石杨氏模量；D代表裂缝等效直径，D＝4*(A/S)，A是裂缝某一截面积，S是该截面的周长；e代表裂缝的厚度，这里取无穷大。In the above formula, K represents the elastic modulus of the fracturing fluid; ρ represents the density of the fracturing fluid; E represents the Young’s modulus of the rock; D represents the equivalent diameter of the fracture, D=4*(A/S), and A is a section of the fracture area, S is the perimeter of the section; e represents the thickness of the crack, which is infinite here.
以下介绍目标裂缝延伸方向上距离缝口一定距离的位置点处岩石所受到的脉冲压力幅值的计算公式。The calculation formula of the pulse pressure amplitude suffered by the rock at a point in the extension direction of the target fracture at a certain distance from the fracture opening is introduced below.
其中，H代表截面平均水头；V代表截面平均流速；x代表位置；t代表时间；τ0指剪切应力系数；f指Darcy-Weisbach摩擦系数；Re表示雷诺数，d代表裂缝的等效直径d＝4*(A/S),m，其中A表示裂缝截面面积，S表示截面的周长；Among them, H represents the average water head of the cross-section; V represents the average flow velocity of the cross-section; x represents the position; t represents the time;τ0 represents the shear stress coefficient; f represents the Darcy-Weisbach friction coefficient; d=4*(A/S),m, where A represents the cross-sectional area of the crack, and S represents the perimeter of the cross-section;
瞬变流模型的求解特征线法将(17)和(18)两个偏微分方程组化为两个常微分方程组求解：The characteristic line method for solving the transient flow model converts the two partial differential equations (17) and (18) into two ordinary differential equations to solve:
C+:
C-:
上式表示，(17)在直线(18)上成立，(19)在直线(20)上成立。由于所需结果为压力，将上式中的H替换为P，其中P＝ρgH，为方便计算将上式中的速度V替换为流量Q，Q＝A*V。对上式进行差分得到：The above formula shows that (17) is established on the straight line (18), and (19) is established on the straight line (20). Since the desired result is pressure, replace H in the above formula with P, where P=ρgH, and replace the velocity V in the above formula with flow Q for convenience of calculation, Q=A*V. Differentiate the above formula to get:
C+:
C-:
求解过程中利用已知的当前时刻A点和B点的压力和流量值，求解得到下一时刻P点压力和流量的值，以此类推可得到目标裂缝中各位置在所有时刻的压力和流量值。In the process of solving, use the known pressure and flow values of point A and point B at the current moment to solve the value of pressure and flow at point P at the next moment, and so on to obtain the pressure and flow of each position in the target fracture at all times value.
本说明书实施例还提供了一种裂缝的起裂装置，可以用于实现上述任一裂缝的起裂方法。如图8A所示，该装置包括第一获取模块10和控制模块20。The embodiment of the present specification also provides a crack initiation device, which can be used to implement any of the crack initiation methods described above. As shown in FIG. 8A , the device includes a
第一获取模块10用于获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；缝口为目标裂缝的起裂点，缝尖为目标裂缝延伸方向上远离缝口的位置。The
控制模块20用于当目标裂缝的缝尖被封堵，且缝口被封堵在与目标裂缝相交的裂缝中或与目标裂缝相交的井筒中时，控制脉冲泵在目标裂缝的缝口施加脉冲压力，使得目标裂缝延伸方向上的至少一个点起裂，其中，脉冲压力的频率为液柱的一个阶数的固有频率。The
在一些实施例中，如图8B所示，第一获取模块10包括第一确定子模块11、第二确定子模块12和选取子模块13。In some embodiments, as shown in FIG. 8B , the
第一确定子模块11用于确定向目标裂缝的缝口施加各阶数的固有频率的脉冲压力时，在目标裂缝在延伸方向上岩石所受到的脉冲压力幅值的变化趋势。第二确定子模块12用于根据变化趋势，确定脉冲压力幅值中极大值的位置和/或极大值的个数。选取子模块13用于根据极大值的位置和/或极大值的个数，选取一个阶数的固有频率。The
在一些实施例中，如图8B所示，第一获取模块10还包括第三确定子模块14和增大子模块15。In some embodiments, as shown in FIG. 8B , the first obtaining
第三确定子模块14用于确定各极大值的取值。增大子模块15用于当极大值中取值最大者的取值小于岩石抗拉强度的预定比例时，增大所施加的脉冲压力的幅值，以重新确定在目标裂缝延伸方向上岩石所受到的脉冲压力幅值的变化趋势。The
在一些实施例中，如图8B所示，第一获取模块10包括第一获取子模块16、第一获取子模块17和计算子模块18。In some embodiments, as shown in FIG. 8B , the
第一获取子模块16用于获取目标裂缝的缝口至缝尖内所填充的压裂液的密度和弹性模量。第一获取子模块17用于获取目标裂缝的长度。计算子模块18用于根据以下公式计算固有频率：The first acquisition sub-module 16 is used to acquire the density and elastic modulus of the fracturing fluid filled in the target fracture from the opening to the tip of the fracture. The first obtaining
其中，n为自然数，f为固有频率，f的下标表示固有频率的阶数，l为裂缝的长度，a为脉冲压力波传播速度。Among them, n is a natural number, f is the natural frequency, the subscript of f indicates the order of the natural frequency, l is the length of the fracture, and a is the propagation velocity of the pulse pressure wave.
在一些实施例中，如图8B所示，裂缝的起裂装置还包括第二获取模块30和确定模块40。In some embodiments, as shown in FIG. 8B , the crack initiation device further includes a
第二获取模块30用于获取产生目标裂缝时在目标裂缝的缝口处监测到的破裂压力。确定模块40用于将破裂压力与预定系数的乘积作为所施加的脉冲压力的幅值。The
上述裂缝的起裂装置的相关描述及效果请参阅本说明书实施例中对应的方法实施例，不再赘述。For the relevant description and effects of the above-mentioned crack initiation device, please refer to the corresponding method embodiments in the embodiments of this specification, and details will not be repeated here.
本说明书实施例还提供了一种裂缝的起裂系统，可以用于实现上述任意一种裂缝的起裂方法。该系统包括至少两个封隔器、控制器和脉冲泵。The embodiment of the present specification also provides a crack initiation system, which can be used to implement any of the above-mentioned crack initiation methods. The system includes at least two packers, a controller and a pulse pump.
封隔器用于将目标裂缝的缝口封堵在与目标裂缝相交的裂缝中或与目标裂缝相交的井筒中。用于获取目标裂缝的缝口至缝尖内所填充的液柱的一个阶数的固有频率；缝口为目标裂缝的起裂点，缝尖为目标裂缝延伸方向上远离缝口的位置；并控制脉冲泵产生预定频率的脉冲压力。脉冲泵用于当目标裂缝的缝尖被封堵，且缝口被封堵在与目标裂缝相交的裂缝中或与目标裂缝相交的井筒中时，在目标裂缝的缝口施加脉冲压力，使得目标裂缝的延伸方向上的至少一个点起裂，其中，脉冲压力的频率为液柱的一个阶数的固有频率。The packer is used to seal the opening of the target fracture in the fracture intersecting the target fracture or in the wellbore intersecting the target fracture. It is used to obtain the natural frequency of one order of the liquid column filled in the crack opening to the crack tip of the target fracture; the crack opening is the crack initiation point of the target fracture, and the crack tip is the position away from the crack opening in the extension direction of the target fracture; and The pulse pump is controlled to generate pulse pressure at a predetermined frequency. The pulse pump is used to apply pulse pressure to the opening of the target fracture when the tip of the target fracture is blocked and the opening is blocked in the fracture intersecting with the target fracture or in the wellbore intersecting with the target fracture, so that the target A crack is initiated at at least one point in the extending direction of the crack, wherein the frequency of the pulse pressure is a natural frequency of an order of the liquid column.
本发明实施例还提供了一种控制器，如图9所示，该控制器可以包括处理器91和存储器92，其中处理器91和存储器92可以通过总线或者其他方式连接，图9中以通过总线连接为例。The embodiment of the present invention also provides a controller. As shown in FIG. 9, the controller may include a
处理器91可以为中央处理器(Central Processing Unit，CPU)。处理器91还可以为其他通用处理器、数字信号处理器(Digital Signal Processor，DSP)、专用集成电路(Application Specific Integrated Circuit，ASIC)、现场可编程门阵列(Field-Programmable Gate Array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等芯片，或者上述各类芯片的组合。The
存储器92作为一种非暂态计算机可读存储介质，可用于存储非暂态软件程序、非暂态计算机可执行程序以及模块，如本发明实施例中的裂缝的起裂方法对应的程序指令/模块(例如，图8A所示的第一获取模块10和控制模块20)。处理器91通过运行存储在存储器92中的非暂态软件程序、指令以及模块，从而执行处理器的各种功能应用以及数据处理，即实现上述方法实施例中的裂缝的起裂方法。The
存储器92可以包括存储程序区和存储数据区，其中，存储程序区可存储操作系统、至少一个功能所需要的应用程序；存储数据区可存储处理器91所创建的数据等。此外，存储器92可以包括高速随机存取存储器，还可以包括非暂态存储器，例如至少一个磁盘存储器件、闪存器件、或其他非暂态固态存储器件。在一些实施例中，存储器92可选包括相对于处理器91远程设置的存储器，这些远程存储器可以通过网络连接至处理器91。上述网络的实例包括但不限于互联网、企业内部网、局域网、移动通信网及其组合。The
所述一个或者多个模块存储在所述存储器92中，当被所述处理器91执行时，执行上述实施例中的裂缝的起裂方法。The one or more modules are stored in the
上述控制器具体细节可以参阅上述方法实施例中对应的相关描述和效果进行理解，此处不再赘述。The specific details of the above-mentioned controller can be understood by referring to the corresponding relevant description and effects in the above-mentioned method embodiments, and details are not repeated here.
本领域技术人员可以理解，实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成，所述的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，所述存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM)、随机存储记忆体(Random AccessMemory，RAM)、快闪存储器(Flash Memory)、硬盘(Hard Disk Drive，缩写：HDD)或固态硬盘(Solid-State Drive，SSD)等；所述存储介质还可以包括上述种类的存储器的组合。Those skilled in the art can understand that all or part of the processes in the methods of the above-mentioned embodiments can be completed by instructing related hardware through computer programs, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium can be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a flash memory (Flash Memory), a hard disk (Hard Disk Drive, abbreviation: HDD) or a solid-state drive (Solid-State Drive, SSD), etc.; the storage medium may also include a combination of the above-mentioned types of memory.
在20世纪90年代，对于一个技术的改进可以很明显地区分是硬件上的改进(例如，对二极管、晶体管、开关等电路结构的改进)还是软件上的改进(对于方法流程的改进)。然而，随着技术的发展，当今的很多方法流程的改进已经可以视为硬件电路结构的直接改进。设计人员几乎都通过将改进的方法流程编程到硬件电路中来得到相应的硬件电路结构。因此，不能说一个方法流程的改进就不能用硬件实体模块来实现。例如，可编程逻辑器件(Programmable Logic Device,PLD)(例如现场可编程门阵列(Field Programmable GateArray，FPGA))就是这样一种集成电路，其逻辑功能由用户对器件编程来确定。由设计人员自行编程来把一个数字系统“集成”在一片PLD上，而不需要请芯片制造厂商来设计和制作专用的集成电路芯片2。而且，如今，取代手工地制作集成电路芯片，这种编程也多半改用“逻辑编译器(logic compiler)”软件来实现，它与程序开发撰写时所用的软件编译器相类似，而要编译之前的原始代码也得用特定的编程语言来撰写，此称之为硬件描述语言(Hardware Description Language，HDL)，而HDL也并非仅有一种，而是有许多种，如ABEL(Advanced Boolean Expression Language)、AHDL(Altera Hardware DescriptionLanguage)、Confluence、CUPL(Cornell University Programming Language)、HDCal、JHDL(Java Hardware Description Language)、Lava、Lola、MyHDL、PALASM、RHDL(RubyHardware Description Language)等，目前最普遍使用的是VHDL(Very-High-SpeedIntegrated Circuit Hardware Description Language)与Verilog2。本领域技术人员也应该清楚，只需要将方法流程用上述几种硬件描述语言稍作逻辑编程并编程到集成电路中，就可以很容易得到实现该逻辑方法流程的硬件电路。In the 1990s, the improvement of a technology can be clearly distinguished as an improvement in hardware (for example, improvements in circuit structures such as diodes, transistors, and switches) or improvements in software (improvement in method flow). However, with the development of technology, the improvement of many current method flows can be regarded as the direct improvement of the hardware circuit structure. Designers almost always get the corresponding hardware circuit structure by programming the improved method flow into the hardware circuit. Therefore, it cannot be said that the improvement of a method flow cannot be realized by hardware physical modules. For example, a Programmable Logic Device (Programmable Logic Device, PLD) (such as a Field Programmable Gate Array (Field Programmable Gate Array, FPGA)) is such an integrated circuit, and its logic function is determined by programming the device by a user. It is programmed by the designer to "integrate" a digital system on a PLD, instead of asking a chip manufacturer to design and manufacture a dedicated integrated circuit chip 2 . Moreover, nowadays, instead of making integrated circuit chips by hand, this kind of programming is mostly realized by "logic compiler (logic compiler)" software, which is similar to the software compiler used when writing programs. The original code of the computer must also be written in a specific programming language, which is called a hardware description language (Hardware Description Language, HDL), and there is not only one kind of HDL, but many kinds, such as ABEL (Advanced Boolean Expression Language) , AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc., currently the most commonly used is VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog2. It should also be clear to those skilled in the art that only a little logical programming of the method flow in the above-mentioned hardware description languages and programming into an integrated circuit can easily obtain a hardware circuit for realizing the logic method flow.
本说明书中的各个实施方式均采用递进的方式描述，各个实施方式之间相同相似的部分互相参见即可，每个实施方式重点说明的都是与其他实施方式的不同之处。Each implementation in this specification is described in a progressive manner, the same and similar parts of each implementation can be referred to each other, and each implementation focuses on the differences from other implementations.
上述实施方式阐明的系统、装置、模块或单元，具体可以由计算机芯片或实体实现，或者由具有某种功能的产品来实现。The systems, devices, modules, or units described in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions.
为了描述的方便，描述以上装置时以功能分为各种单元分别描述。当然，在实施本申请时可以把各单元的功能在同一个或多个软件和/或硬件中实现。For the convenience of description, when describing the above devices, functions are divided into various units and described separately. Of course, when implementing the present application, the functions of each unit can be implemented in one or more pieces of software and/or hardware.
通过以上的实施方式的描述可知，本领域的技术人员可以清楚地了解到本申请可借助软件加必需的通用硬件平台的方式来实现。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品可以存储在存储介质中，如ROM/RAM、磁碟、光盘等，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施方式的某些部分的方法。It can be known from the above description of the implementation manners that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general-purpose hardware platform. Based on this understanding, the essence of the technical solution of this application or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in storage media, such as ROM/RAM, disk , optical disc, etc., including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute some methods of various embodiments of the present application.
本申请可用于众多通用或专用的计算机系统环境或配置中。例如：个人计算机、服务器计算机、手持设备或便携式设备、平板型设备、多处理器系统、基于微处理器的系统、置顶盒、可编程的消费电子设备、网络PC、小型计算机、大型计算机、包括以上任何系统或设备的分布式计算环境等等。The application can be used in numerous general purpose or special purpose computer system environments or configurations. Examples: personal computers, server computers, handheld or portable devices, tablet-type devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, including A distributed computing environment for any of the above systems or devices, etc.
本申请可以在由计算机执行的计算机可执行指令的一般上下文中描述，例如程序模块。一般地，程序模块包括执行特定任务或实现特定抽象数据类型的例程、程序、对象、组件、数据结构等等。也可以在分布式计算环境中实践本申请，在这些分布式计算环境中，由通过通信网络而被连接的远程处理设备来执行任务。在分布式计算环境中，程序模块可以位于包括存储设备在内的本地和远程计算机存储介质中。This application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including storage devices.
虽然通过实施方式描绘了本申请，本领域普通技术人员知道，本申请有许多变形和变化而不脱离本申请的精神，希望所附的权利要求包括这些变形和变化而不脱离本申请的精神。Although the present application has been described by means of embodiments, those of ordinary skill in the art know that there are many variations and changes in the present application without departing from the spirit of the application, and it is intended that the appended claims cover these variations and changes without departing from the spirit of the application.
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