CN110130864B - Near-wellbore crack control method based on staggered fixed-face perforation - Google Patents
Near-wellbore crack control method based on staggered fixed-face perforation Download PDFInfo
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Abstract
The invention discloses a near-wellbore crack control method based on staggered fixed-face perforation, which comprises the following steps: determining a near-wellbore fracture to be formed according to geological conditions of a reservoir, wherein the near-wellbore fracture to be formed comprises: the phase angle range of the fracture and the fracture type; setting a plurality of perforation planes according to the phase angle range of the crack, wherein two adjacent perforation planes are arranged in parallel and in a staggered manner, the phase angle range of each perforation plane is at least partially overlapped with the phase angle range of the crack, and the phase angle range covered by the plurality of perforation planes comprises the phase angle range of the crack; determining a corresponding perforating charge according to the fracture type; and carrying out perforation according to the perforating charges and the plurality of perforation fixed surfaces so as to control the formation of near-wellbore cracks. The invention solves the technical problem that the prior art is difficult to effectively control the trend and the expansion of the near-wellbore fracture.
Description
Technical Field
The invention relates to the technical field of volume fracturing production increase of conventional and unconventional oil and gas reservoirs, in particular to a near-wellbore fracture control method based on staggered fixed-face perforation.
Background
The perforation technology is taken as a core technical link of a fracturing well completion technology, the development is rapid in recent years, particularly along with the development of oil and gas fields, the development is continuously advanced towards unconventional oil and gas reservoirs with low porosity and low permeability, such as shale gas, dense gas, coal bed gas and the like, the perforation plays the roles of opening an oil casing, communicating a shaft and a stratum in the tradition, and meanwhile, the perforation technology also plays more and more roles in controlling the trend of cracks, promoting the formation of a fracture network and realizing volume fracturing, so that the perforation technology is continuously concerned by researchers.
When the long horizontal-section horizontal well is fractured in a large-scale and sectional manner, the commonly used perforation modes comprise spiral perforation, directional perforation and fixed-face perforation, the several perforation modes are mature relative to the technology, and the requirements of reducing the fracture initiation pressure and promoting the formation of a fracture network can be met to a certain extent through optimizing perforation parameters. However, at present, due to the reasons that the physical form of the cracks around the hole is complex, the communication form is various, the forming mechanism and the expansion rule are not clear and the like during perforation, how to realize effective manual control on the cracks of the near wellbore by optimizing the perforation mode and parameters and further promote the improvement of the fracturing modification effect is still an important problem in the field of perforation fracturing, and the efficient development of unconventional oil and gas reservoirs is also severely restricted, so that the exploration of the manual control method for the cracks of the near wellbore of the unconventional oil and gas reservoirs is very necessary.
Disclosure of Invention
The invention mainly aims to provide a near-wellbore fracture control method based on staggered fixed-face perforation, and aims to solve the technical problem that the prior art is difficult to effectively control the trend and the expansion of a near-wellbore fracture.
In order to achieve the above object, the present invention provides a near-wellbore fracture control method based on staggered fixed-surface perforation, which comprises:
determining a near-wellbore fracture to be formed according to geological conditions of a reservoir, wherein the near-wellbore fracture to be formed comprises: the phase angle range of the fracture and the fracture type;
setting a plurality of perforation planes according to the phase angle range of the crack, wherein two adjacent perforation planes are arranged in parallel and in a staggered manner, the phase angle range of each perforation plane is at least partially overlapped with the phase angle range of the crack, and the phase angle range covered by the plurality of perforation planes comprises the phase angle range of the crack;
determining a corresponding perforating charge according to the fracture type;
and carrying out perforation according to the perforating charges and the plurality of perforation fixed surfaces so as to control the formation of near-wellbore cracks.
Further, the setting a plurality of perforation fixed planes according to the phase angle range of the fracture comprises:
setting a fixed surface included angle of each perforation fixed surface and a staggered angle between two adjacent perforation fixed surfaces according to the phase angle range of the crack;
and arranging the plurality of perforation fixed planes according to the fixed plane included angles and the staggered angles, so that the phase angle range covered by the plurality of perforation fixed planes comprises the phase angle range of the crack.
Further, the arranging the plurality of perforation fixed planes according to the fixed plane included angles and the staggered angles includes:
the projection of the first perforation of each perforation fixed surface on the cross section vertical to the shaft axis of the shaft is arranged along the circumferential direction of the shaft in sequence.
Further, the arranging the plurality of perforation fixed planes according to the fixed plane included angles and the staggered angles includes:
the projections of the first perforation of the part of the plurality of perforation fixed planes on the cross section vertical to the shaft axis are sequentially arranged along the clockwise direction of the shaft, and the projections of the first perforation of the other part of the plurality of perforation fixed planes on the cross section vertical to the shaft axis are sequentially arranged along the anticlockwise direction of the shaft.
Further, the fracture types include: transversely cutting the cracks and the seam net; the determining the corresponding perforating charge according to the fracture type comprises: when the fracture type is a crosscut fracture, selecting a deep penetration perforating bullet; and when the fracture type is a fracture network, selecting a large-aperture perforating charge.
Further, the near-wellbore fracture to be formed comprises: the crack is high; the determining the corresponding perforating charge according to the fracture type comprises: and determining the perforating charge according to the fracture type and the fracture height.
Furthermore, the fixed surface included angles of the fixed surfaces of the perforation are equal.
Furthermore, the staggered angle between any two adjacent perforation fixed planes is equal.
Further, the distance between any two adjacent perforation fixed surfaces is equal.
Further, the distance between any two adjacent perforation fixed planes ranges from 150 mm to 300 mm.
The invention has the beneficial effects that: the invention introduces the perforation parameter of the fixed surface staggered angle on the basis of the conventional fixed surface perforation, so that the fixed surface staggered angle has the double advantages that the connection of the perforation in the same fixed surface is tight and the formation of a communicating crack is easy, and the connection of the perforation between the adjacent fixed surfaces is tight and the formation of the communicating crack is easy.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts. In the drawings:
FIG. 1 is a flow chart of a near-wellbore fracture control method based on staggered fixed-face perforations in accordance with an embodiment of the present invention;
FIG. 2 is a flow chart of a method of setting a perforation profile according to an embodiment of the present invention;
FIG. 3 is one of the schematic illustrations of staggered fixed-plane perforations in accordance with an embodiment of the present invention;
FIG. 4 is a second schematic diagram of alternate fixed-surface perforations in accordance with an embodiment of the present invention;
FIG. 5 is a schematic illustration of a geological condition and a desired near-wellbore fracture according to an embodiment of the present invention;
FIG. 6 is a second schematic illustration of geological conditions and desired near-wellbore fractures according to an embodiment of the present invention;
FIG. 7 is a third schematic illustration of geological conditions and desired near-wellbore fractures according to an embodiment of the present invention;
FIG. 8 is a schematic view of a planar spiral unidirectional layout according to an embodiment of the present invention;
FIG. 9 is one of the schematic views of a 360-degree cross-cut fracture near the wellbore of an embodiment of the invention;
FIG. 10 is a second schematic view of a 360-degree cross-cut fracture near the wellbore in accordance with an embodiment of the present invention;
FIG. 11 is a schematic view of a W-shaped bi-directional layout of a fixed plane according to an embodiment of the present invention;
FIG. 12 is one of the near-wellbore constant angle transverse fractures of an embodiment of the present invention;
FIG. 13 is a second schematic view of a near-wellbore constant-angle transverse fracture in accordance with an embodiment of the present invention;
FIG. 14 is a schematic view of a mixed arrangement of the embodiment of the present invention;
fig. 15 is a schematic phase angle diagram of an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of the present invention and the above-described drawings, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
The invention provides a perforation mode of staggered fixed-face perforation for realizing near-wellbore crack control. In the invention, the concept of staggered fixed-plane perforation is provided based on the idea that the manual control of the near-wellbore fracture behavior is realized, the connection among all pore canals is strengthened to promote the formation of the communicated fracture around the pore canal and the connection among the communicated fractures around the pore canal to promote the formation of the transverse main seam or an effective means is provided.
Fig. 3 and 4 are schematic views of staggered fixed-plane perforations according to embodiments of the present invention, in which fig. 3 and 4: 1 is the fixed face of the first fixed face perforation, 2 is the fixed face of the second fixed face perforation, 3 is the perforation, 4 is the cross section perpendicular to the axis of the wellbore, 4 is the intersection region of the first fixed face 1 and the second fixed face 2, 6 is the fixed face intersection angle of the first fixed face 1 and the second fixed face 2, and 7 is the fixed face included angle of the first fixed face 1. The fixed surface perforation is a mature perforation mode in the prior art, the fixed surface of the fixed surface perforation is a sector, each fixed surface is provided with 3 perforations, the included angle between every two adjacent perforations in one fixed surface is equal and is called as a fixed surface included angle, and the fixed surface is generally arranged to be parallel to a cross section 4 perpendicular to the shaft axis.
As shown in figures 3 and 4, the invention introduces the perforation parameter of the fixed surface staggered angle on the basis of the conventional fixed surface perforation in the staggered fixed surface perforation, leads the sector formed by the 3 launching holes of the adjacent fixed surfaces to form the staggering, and can keep the advantages of tight connection of the launching holes in the same fixed surface and easy formation of hole periphery communication cracks in the conventional fixed surface perforation on one hand and strengthen the connection between the adjacent fixed surface perforations on the other hand by adjusting the size combination of the fixed surface included angle and the fixed surface staggered angle, thereby promoting the expansion and convergence of a plurality of hole periphery communication cracks to form the manually controllable transverse cutting main cracks as required. In fig. 3 and 4, the included angle 7 of the fixed surface represents the angle between two adjacent launching holes in the same fixed surface, similar to the phase angle in the spiral perforation, and the staggered angle of the fixed surface represents the angle between the first launching holes of the adjacent fixed surfaces.
In the invention, in order to find out the expansion rule of the near-well casing crack in the staggered fixed-plane perforation, a perforating and target hitting experiment is carried out on the simulated shale target by adopting a deep penetration DP44RDX38-1 perforating bullet and a large-aperture GH46RDX43-1 perforating bullet, and the real perforation process of the staggered fixed-plane perforation is simulated. The experimental results show that (1) for the deep penetration DP44RDX38-1 perforating charge, a rhombus-shaped transverse fracture perpendicular to the axial direction of the wellbore can be formed when the combination of the included angle of the fixed surface and the staggered angle is 60 degrees +30 degrees. (2) For a large-aperture GH46RDX43-1 perforating bullet, when the combination of the fixed face included angle + the staggered angle is 60 degrees +30 degrees and 60 degrees, a hole periphery crack network is formed, namely rocks around a near-well cylinder are broken when the perforating bullet explodes. An important conclusion can be obtained by researching the forming mechanism and the propagation rule of the cracks around the staggered fixed-face perforation hole: for perforating bullets of different models, when the combination of the fixed face included angle and the staggered angle is changed, the crack forms around the hole are different, and the important influence on the subsequent fracturing transformation is inevitably generated. This gives the invention an important inspiration: for unconventional oil reservoirs with different characteristics, the manual control of the near-wellbore fracture can be realized by adopting a staggered fixed-face perforation mode and preferably selecting the types of perforating charges, the fixed-face included angles and the staggered angles, so that the desired near-wellbore fracture form is obtained, and the oil and gas reservoir can be better reformed according to the will of people.
Fig. 1 is a flowchart of a near-wellbore fracture control method based on staggered fixed-plane perforation according to an embodiment of the present invention, and as shown in fig. 1, the near-wellbore fracture control method based on staggered fixed-plane perforation according to an embodiment of the present invention includes steps S101 to S104.
Step S101, determining a near wellbore fracture to be formed according to geological conditions of a reservoir, wherein the near wellbore fracture to be formed comprises: the phase angle range of the crack and the type of crack.
In embodiments of the invention, the near-wellbore fracture to be formed is a desired near-wellbore fracture morphology, which is typically determined based on the geological conditions of the reservoir and engineering requirements. Fig. 5, 6 and 7 are schematic diagrams of geological conditions and desired near-wellbore fractures according to an embodiment of the invention, and as shown in fig. 5, for unconventional hydrocarbon reservoirs with good geological conditions, small inclination angle variation and large thickness, the wellbore axis is generally close to or coincident with the reservoir centerline, and it is generally desirable to form a transverse main seam perpendicular to the axial direction of the wellbore, so as to slow down the near-wellbore effect and control near-wellbore expansion. As shown in fig. 6, for unconventional oil and gas reservoirs with special geological conditions, large inclination angle changes or special engineering requirements, the shaft axis sometimes passes through the upper part or the lower part of the reservoir, and the fracture is expected to develop more towards one side of the reservoir, so that the hydraulic energy is utilized to the maximum extent, and the productivity is improved. As shown in fig. 7, for unconventional oil and gas reservoirs with complex geological conditions and severe inclination angle changes, the axis of a wellbore is difficult to accurately penetrate through the reservoir and is usually deviated to one side of the reservoir or penetrates out of the reservoir, the expansion direction of a main seam is generally expected to be close to or coincident with the center line of the reservoir, a transverse main seam vertical to the axial direction of the wellbore is expected to be formed in a well section with the axis of the wellbore close to or coincident with the center line of the reservoir, and fractures are expected to develop more deviated to one side of the reservoir in a well section with the axis of the wellbore. In addition, for unconventional oil and gas reservoirs such as thin difference layers, bottom water-containing oil and gas reservoirs, water flooded layers and the like which are difficult to perform large-scale hydraulic fracturing, a larger oil drainage area is generally expected to be directly obtained on a well wall through perforation, the reservoir fracture pressure is reduced, and a near-wellbore seam network is formed.
In embodiments of the invention, the near-wellbore fracture to be formed has two fracture parameters, at least a phase angle range of the fracture and a fracture type. The phase angle range of the fracture is used to determine the desired location of the near-wellbore fracture. Fig. 15 is a schematic phase angle diagram of an embodiment of the present invention, where the phase angle is shown in fig. 15 as an angle around the axial direction of the wellbore, for example, the highest point of the wellbore may be set to a phase angle of 0 degrees, and the lowest point of the wellbore may be set to a phase angle of 180 degrees. The present invention specifies the desired near-wellbore fracture location by setting a range of phase angles for the desired near-wellbore fracture. In an embodiment of the invention, the fracture type is the desired morphology of the near-wellbore fracture, and in an embodiment of the invention, the fracture type may include: cross cuts, webs of seams, etc.
In an alternative embodiment of the invention, the geological conditions of the reservoir may include: the dip angle change of the reservoir, the thickness of the reservoir, the position relation between the shaft line of the shaft and the central line of the reservoir and the like.
In an alternative embodiment of the invention, the near-wellbore fracture to be formed may comprise: a near wellbore 360-degree transverse fracture, a near wellbore fixed-angle transverse fracture, a near wellbore seam net and the like. For a 360 ° transected fracture near the wellbore, the fracture type is a transected fracture, and the phase angle of the fracture ranges from 0 ° to 360 °. For near-wellbore constant angle transverse fractures, the fracture type is a transverse fracture, and the fracture phase angle range is a certain range selected between 0 ° and 360 °. For near wellbore fracture network, the fracture type is fracture network, and the phase angle range of the fracture can be 0-360 degrees or a certain phase angle range selected between 0-360 degrees.
Step S102, a plurality of perforation fixed surfaces are arranged according to the phase angle range of the crack, wherein two adjacent perforation fixed surfaces are arranged in parallel and in a staggered mode, the phase angle range of each perforation fixed surface is at least partially overlapped with the phase angle range of the crack, and the phase angle ranges covered by the plurality of perforation fixed surfaces comprise the phase angle range of the crack.
The invention provides a perforating mode of staggered fixed-face perforation for realizing near-wellbore fracture control, namely, perforating by adopting a plurality of staggered fixed faces. In the embodiment of the present invention, each fixed surface is a sector with a certain angle, and the angle of the sector is directly determined by the included angle of the fixed surface, for example, when the included angle of the fixed surface is 60 °, the angle of the sector is 120 °. In an embodiment of the present invention, the position of each of the fixed surfaces may be determined using a range of phase angles from the phase angle of the first one of the fixed surfaces to the phase angle of the third one of the fixed surfaces.
In an embodiment of the invention, two adjacent perforation planes in the plurality of perforation planes are arranged parallel to each other and each perforation plane is parallel to a cross-section perpendicular to the wellbore axis. Adjacent ones of the plurality of perforation lands are staggered with a stagger angle therebetween, and in embodiments of the invention the stagger angle between any two adjacent perforation lands may be the same or different. In embodiments of the invention, the range of phase angles of each perforation plan at least partially coincides with the range of fracture phase angles of the desired near-wellbore fracture, and the plurality of perforation plans collectively are arranged to cover a range of phase angles greater than or equal to the range of phase angles of the fracture. In another embodiment of the invention, the plurality of perforation plans are arranged to collectively cover a phase angle range that is approximately the same as the fracture phase angle range of the desired near-wellbore fracture, i.e., the plurality of perforation plans collectively cover a phase angle range that is within 15 percent of the fracture phase angle range.
In an embodiment of the present invention, when a plurality of perforation fixed planes are provided, the fixed plane included angle of each perforation fixed plane and the staggered angle between two adjacent fixed planes can be set according to the desired fracture phase angle range of the near-wellbore fracture, so that the phase angle range covered by the whole plurality of provided perforation fixed planes includes the phase angle range of the fracture. In the embodiment of the present invention, the number of the perforation fixed planes and the distance between two adjacent fixed planes are determined by actual engineering requirements, and the arrangement of the plurality of perforation fixed planes may be various, for example, sequentially arranged in the clockwise direction or the counterclockwise direction of the wellbore, bidirectionally arranged in a mixed manner in the clockwise direction and the counterclockwise direction of the wellbore, staggered arranged in a W shape or a V shape within the phase angle range of the fracture, and the like, and the specific arrangement may be determined by actual engineering requirements.
The invention adopts the perforation mode of staggered fixed-surface perforation, namely, adopts a plurality of staggered fixed surfaces to carry out perforation, on one hand, the advantages of tight connection and easy formation of hole periphery communication cracks of the inner perforation of the same fixed surface in the conventional fixed-surface perforation can be kept, and on the other hand, the connection between the adjacent fixed-surface perforations can be enhanced, thereby promoting the plurality of hole periphery communication cracks to expand and converge to form the desired cracks as required.
And S103, determining a corresponding perforating charge according to the fracture type.
In the embodiment of the invention, different types of fractures need to be realized by using different types of perforating charges, and after the desired near-wellbore fracture is determined, the corresponding perforating charge needs to be selected according to the type of the desired near-wellbore fracture.
In embodiments of the invention, the fracture types include transected fractures, for which deep-penetrating charges are selected for perforation, and slotted screens, for which large-aperture charges are selected for perforation.
In an embodiment of the invention, the near-wellbore fracture to be formed also has a fracture height parameter, the fracture height being indicative of the distance of the fracture from the wellbore, the fracture height being determined by the penetration depth of the perforating charges. In one embodiment of the invention, the selection of the perforating charge is based not only on the fracture type but also on the fracture height parameter.
And step S104, perforating according to the perforating charges and the plurality of perforating fixed surfaces so as to control the formation of near-wellbore cracks.
In embodiments of the present invention, after setting the perforation profile and selecting the charges according to the desired near-wellbore fracture, a perforating operation is performed to effect the formation of the desired near-wellbore fracture through perforation promotion.
The invention can be seen from the above description, by introducing the perforation parameter of the fixed surface staggered angle on the basis of the conventional fixed surface perforation, the invention has the dual advantages that the connection of the perforation in the same fixed surface is tight and the connection of the perforation between adjacent fixed surfaces is tight and the connection of the perforation is easy to form, and the specific hole peripheral crack form can be promoted to be formed by adjusting the type of the perforating bullet and the combination of the fixed surface included angle and the staggered angle, thereby enhancing the control capability of manual work on the near-wellbore crack connection and expansion and laying a good foundation for the final efficient fracturing reconstruction.
Fig. 2 is a flowchart of a perforation setting method according to an embodiment of the present invention, and as shown in fig. 2, the perforation setting method of step S102 specifically includes step S201 and step S202.
Step S201, setting a fixed surface included angle of each perforation fixed surface and a staggered angle between two adjacent perforation fixed surfaces according to the phase angle range of the crack.
In the embodiment of the invention, the fixed surface included angle of each perforation fixed surface can be set to be the same value, and can also be set to be different values according to requirements. In the embodiment of the invention, the staggered angle between any two adjacent perforation fixed planes can be set to be the same value, and can also be set to be different values according to requirements. In a preferred embodiment of the invention, the set angles of each perforation set are equal, and the stagger angle between any two adjacent perforation sets is equal.
In the embodiment of the invention, when a plurality of staggered fixed surfaces are adopted for perforation, the fixed surface included angle of the perforation fixed surfaces and the staggered angle between two adjacent perforation fixed surfaces need to be set, and then the plurality of perforation fixed surfaces are arranged. In the invention, the fixed face included angle of the perforation fixed faces and the staggered angle between two adjacent perforation fixed faces are set according to the crack phase angle range of the desired near-wellbore crack. When the fracture phase angle range is large, for example, for a 360 ° transected fracture near the wellbore, the fracture phase angle range is 0 ° to 360 °, the face angle of the fixed face can be set to be slightly larger, for example, 60 ° or 90 °, and the stagger angle between two adjacent perforation fixed faces can also be set to be slightly larger, for example, between 60 ° and 120 °. When the fracture phase angle range is small, for example, the fracture is transversely cut at a fixed angle near the well casing in a phase angle range of 30-150 degrees, the fracture phase angle range is small, the included angle of the fixed planes can be set to be small, for example, 30-45 degrees, and the staggered angle between two adjacent fixed planes of the perforation needs to be set to be small, for example, 10-30 degrees.
In an embodiment of the invention, the fixed face angle of the perforation fixed face and the stagger angle between two adjacent perforation fixed faces are set according to the crack phase angle range of the desired near-wellbore crack, and in general, the fixed face angle of the fixed face and the stagger angle between two adjacent perforation fixed faces are set to be larger when the crack phase angle range is larger, and the fixed face angle of the fixed face and the stagger angle between two adjacent perforation fixed faces are set to be smaller when the crack phase angle range is smaller. In addition, the arrangement of the fixed face included angle of the perforation fixed face and the staggered angle between two adjacent perforation fixed faces also needs to take actual engineering requirements into consideration, because when the fixed face included angle and the staggered angle are arranged to be smaller, the number of the fixed faces required for covering a certain phase angle range is increased, and the perforation cost is increased, so that the arrangement of the fixed face included angle and the staggered angle needs to comprehensively consider the desired near-wellbore fracture and the actual engineering requirements.
In the embodiment of the invention, the included angle of the fixed surface can be 30 degrees, 45 degrees, 60 degrees or 90 degrees according to requirements. The value range of the staggered angle between two adjacent perforation fixed surfaces is a fixed surface included angle of the fixed surface which is more than 0 and less than two times.
In the embodiment of the invention, the distance between any two adjacent perforation fixed planes can be equal, and can also be set to be unequal according to requirements. The distance between the adjacent fixed surfaces is determined by actual engineering requirements, and the value range of the adjacent distance is more than or equal to 150 mm and less than or equal to 300 mm. In a preferred embodiment of the invention, the distance between any two adjacent perforation planes is set equal.
Step S202, arranging the plurality of perforation fixed planes according to the fixed plane included angles and the staggered angles, so that the phase angle range covered by the plurality of perforation fixed planes comprises the phase angle range of the fracture.
In embodiments of the present invention, after determining the face angle for each perforation face, the angle covered by the perforation face is determined. After the stagger angle between the adjacent two fixed surfaces is determined, the positional relationship between the adjacent two fixed surfaces can be roughly determined. It should be noted that the fixed-surface staggered angle represents an angle between the initial perforations of adjacent fixed surfaces, and for the same staggered angle, two different fixed-surface positional relationships may occur, that is, for the same staggered angle, the initial perforations of the second fixed surface may be on both sides of the initial perforations of the first fixed surface. For example, when the stagger angle is set to 30 ° and the phase angle of the first stationary plane ranges from 50 ° to 170 °, the phase angle of the second stationary plane may range from 20 ° to 140 ° or from 80 ° to 200 °. Therefore, after the fixed face included angles and the staggered angles are determined, the arrangement modes of the perforation fixed faces can be various, when the perforation fixed faces are arranged, the phase angle range covered by all the arranged perforation fixed faces needs to be met, the phase angle range of the crack needs to be included, and the phase angle range of each perforation fixed face at least partially coincides with the phase angle range of the crack.
In the embodiment of the present invention, the arrangement of the perforation fixed planes may be various, for example, the perforation fixed planes are sequentially arranged along the clockwise direction or the counterclockwise direction of the wellbore, are arranged along the clockwise direction and the counterclockwise direction of the wellbore in a mixed manner, are staggered in a W-shape or a V-shape within the phase angle range of the fracture, and the specific arrangement mode may be determined by actual engineering requirements.
In an alternative embodiment of the invention, all perforation fixes may be arranged as: the projections of the first perforation of each perforation fixed surface on the cross section perpendicular to the axis of the shaft are sequentially arranged along the circumferential direction of the shaft, as shown in fig. 8, all the fixed surfaces are sequentially arranged along the circumferential direction of the shaft to form a spiral one-way arrangement mode surrounding the shaft, and the arrangement mode can be well applied to 360-degree transverse fracture close to the shaft.
In an alternative embodiment of the invention, the arrangement of the perforation planes provided may be: projections of first perforations of a part of the perforation fixed planes in all the arranged perforation fixed planes on a cross section vertical to the shaft axis are sequentially arranged along the clockwise direction of the shaft, projections of first perforations of a part of the perforation fixed planes on a cross section vertical to the shaft axis are sequentially arranged along the anticlockwise direction of the shaft, and the arrangement mode is a W-shaped arrangement mode shown in figure 11. This arrangement is also various, the W-shaped arrangement of fig. 11 is only one example, and for example, V-shaped, M-shaped, N-shaped, etc. arrangements are also possible according to actual needs.
The invention also tests the proposed near-wellbore fracture control method based on staggered fixed-face perforation, and provides the following embodiments:
example one, controlled formation of a 360 ° transected fracture near the wellbore
For unconventional hydrocarbon reservoirs with good geological conditions, small inclination angle changes and large thickness, the wellbore axis is generally close to or coincident with the reservoir centerline, as shown in fig. 5. In this case, it is generally desirable to form a transverse main slit perpendicular to the axial direction of the wellbore, thereby alleviating the near wellbore effect and controlling the near-wellbore distance. At this time, a deep penetration perforation DP44RDX38-1 perforating charge is adopted, and a combination of a fixed face included angle + a staggered angle of 60 degrees +30 degrees is adopted. This can be achieved by arranging the fixed planes in a spiral unidirectional encircling wellbore as shown in fig. 8. as shown in fig. 9 and 10, adjacent fixed planes are communicated through rhombic transverse fractures during perforation detonation and encircle the wellbore for 360 degrees, so that the near wellbore 360-degree transverse fractures are easier to expand and develop into large transverse main fractures encircling the wellbore during subsequent fracturing.
Example two control formation of near wellbore constant angle transverse fractures
For unconventional hydrocarbon reservoirs with special geological conditions, large changes in dip angle, or special engineering requirements, the wellbore axis sometimes passes above or below the reservoir as shown in fig. 6. In this case, it is generally desirable that the fractures develop more toward one side of the reservoir, so as to maximize the utilization of hydraulic energy and improve productivity. At this time, a deep penetration perforation DP44RDX38-1 perforating charge is adopted, and a combination of a fixed face included angle + a staggered angle of 60 degrees +30 degrees is adopted. As shown in fig. 11, at this time, the fixed surfaces may adopt a W-shaped bidirectional arrangement method, and this goal may be achieved, as shown in fig. 12 and 13, when the perforation is detonated, the adjacent fixed surfaces may be communicated through the rhombic transverse cut crack and twisted at one side of the wellbore according to the W shape to form a near-wellbore transverse cut crack with a fixed angle, so that during subsequent fracturing, the near-wellbore transverse cut crack with a fixed angle is more easily expanded and developed into a large transverse cut main crack biased to one side of the wellbore and controlling a certain circumferential angle.
EXAMPLE III control of near wellbore seam formation
For unconventional oil and gas reservoirs such as thin difference layers, bottom water-containing oil and gas reservoirs, water flooded layers and the like which are difficult to perform large-scale hydraulic fracturing, a larger oil drainage area is generally expected to be directly obtained on a well wall through perforation, the reservoir fracture pressure is reduced, and a near-wellbore seam network is formed. At the moment, a large-aperture GH46RDX43-1 perforating bullet is adopted, a combination of a fixed surface included angle + a staggered angle of 60 degrees +30 degrees is adopted, and each fixed surface adopts a spiral one-way surrounding shaft arrangement method as shown in figure 8, so that the aim can be achieved. Under the perforation parameter, because the distance of the perforating bullet is short, energy release is concentrated, and rocks near the well casing can be cracked during perforation detonation, so that a near well casing seam network can be directly formed.
Example four control of near wellbore multidirectional transecting fractures
As shown in fig. 7, for unconventional oil and gas reservoirs with complex geological conditions and severe inclination angle changes, the axis of a wellbore is difficult to accurately penetrate through the reservoir and is usually deviated to one side of the reservoir or penetrates out of the reservoir, the expansion direction of a main seam is generally expected to be close to or coincident with the center line of the reservoir, a transverse main seam vertical to the axial direction of the wellbore is expected to be formed in a well section with the axis of the wellbore close to or coincident with the center line of the reservoir, and fractures are expected to develop more deviated to one side of the reservoir in a well section with the axis of the wellbore. It is therefore desirable to form the transverse main slit at different angles in different intervals of the reservoir. At this point, a deep penetration perforation DP44RDX38-1 charge may be used, taking the combination of set face angle + stagger angle of 60 + 30. As shown in fig. 14, at this time, according to the actual situation of the reservoir in different well sections, the formation of the cross-cut fracture at multiple well sections of the reservoir can be controlled by adopting a spiral unidirectional arrangement method and an M-shaped bidirectional arrangement method according to the position mixture of the reservoir.
The invention can be seen from the above description, by introducing the perforation parameter of the fixed surface staggered angle on the basis of the conventional fixed surface perforation, the invention has the dual advantages that the connection of the perforation in the same fixed surface is tight and the connection of the perforation between adjacent fixed surfaces is tight and the connection of the perforation is easy to form, and the specific hole peripheral crack form can be promoted to be formed by adjusting the type of the perforating bullet and the combination of the fixed surface included angle and the staggered angle, thereby enhancing the control capability of manual work on the near-wellbore crack connection and expansion and laying a good foundation for the final efficient fracturing reconstruction.
It should be noted that certain steps shown in the flowchart of the figure may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different than here.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A near-wellbore fracture control method based on staggered fixed-face perforation is characterized by comprising the following steps:
determining a near-wellbore fracture to be formed according to geological conditions of a reservoir, wherein the near-wellbore fracture to be formed comprises: the phase angle range of the fracture and the fracture type;
setting a plurality of perforation planes according to the phase angle range of the crack, wherein two adjacent perforation planes are arranged in parallel and in a staggered manner, the phase angle range of each perforation plane is at least partially overlapped with the phase angle range of the crack, and the phase angle range covered by the plurality of perforation planes comprises the phase angle range of the crack;
determining a corresponding perforating charge according to the fracture type;
perforating according to the perforating charges and the plurality of perforating fixed surfaces so as to control the formation of near-wellbore cracks;
the setting of the plurality of perforation fixed planes according to the phase angle range of the fracture comprises the following steps:
setting a fixed surface included angle of each perforation fixed surface and a staggered angle between two adjacent perforation fixed surfaces according to the phase angle range of the crack;
and arranging the plurality of perforation fixed planes according to the fixed plane included angles and the staggered angles, so that the phase angle range covered by the plurality of perforation fixed planes comprises the phase angle range of the crack.
2. The method for near-wellbore fracture control based on staggered set-top perforations of claim 1, wherein the arranging the plurality of perforation sets according to the set-top angles and the staggered angles comprises:
the projection of the first perforation of each perforation fixed surface on the cross section vertical to the shaft axis of the shaft is arranged along the circumferential direction of the shaft in sequence.
3. The method for near-wellbore fracture control based on staggered set-top perforations of claim 1, wherein the arranging the plurality of perforation sets according to the set-top angles and the staggered angles comprises:
the projections of the first perforation of the part of the plurality of perforation fixed planes on the cross section vertical to the shaft axis are sequentially arranged along the clockwise direction of the shaft, and the projections of the first perforation of the other part of the plurality of perforation fixed planes on the cross section vertical to the shaft axis are sequentially arranged along the anticlockwise direction of the shaft.
4. The near-wellbore fracture control method based on staggered fixed-face perforations of claim 1, wherein the fracture types comprise: transversely cutting the cracks and the seam net;
the determining the corresponding perforating charge according to the fracture type comprises:
when the fracture type is a crosscut fracture, selecting a deep penetration perforating bullet;
and when the fracture type is a fracture network, selecting a large-aperture perforating charge.
5. The method of claim 1, wherein the near-wellbore fracture to be formed comprises: the crack is high;
the determining the corresponding perforating charge according to the fracture type comprises:
and determining the perforating charge according to the fracture type and the fracture height.
6. The method of near-wellbore fracture control based on staggered given-face perforations of claim 1, wherein the included face angle of each of the perforation given faces is equal.
7. The near-wellbore fracture control method based on staggered face-defining perforations of claim 1, wherein the staggered angle between any two adjacent perforation faces is equal.
8. The method of near-wellbore fracture control based on staggered-face perforations of claim 1, wherein the distance between any two adjacent perforation faces is equal.
9. The method of claim 1, wherein the distance between any two adjacent perforation planes ranges from 150 mm to 300 mm.
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| CN103452535B (en) * | 2013-09-22 | 2016-01-20 | 中国石油集团川庆钻探工程有限公司 | Face perforator is determined in a kind of Oil/gas Well module bullet holder |
| CN104358549B (en) * | 2014-11-14 | 2017-02-22 | 山东北方民爆器材有限公司 | Perforated face oriented perforator for oil and gas wells |
| CN105064968A (en) * | 2015-08-14 | 2015-11-18 | 西安通源石油科技股份有限公司 | Oil and gas well fixed-face perforation fracturing device for hydrofracture |
| CN105443100A (en) * | 2015-12-21 | 2016-03-30 | 中国石油天然气股份有限公司 | Fracturing method for fixed-plane perforation joint height control |
| CN207212319U (en) * | 2017-06-07 | 2018-04-10 | 中国石油天然气股份有限公司华北油田分公司 | A kind of water-jet multistage fracturing Crack Control instrument |
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