CN112211611A - Oil and gas reservoir acid fracturing method - Google Patents
Oil and gas reservoir acid fracturing method Download PDFInfo
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- CN112211611A CN112211611A CN202011196455.7A CN202011196455A CN112211611A CN 112211611 A CN112211611 A CN 112211611A CN 202011196455 A CN202011196455 A CN 202011196455A CN 112211611 A CN112211611 A CN 112211611A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/516—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls characterised by their form or by the form of their components, e.g. encapsulated material
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/261—Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation
Abstract
The disclosure provides an acid fracturing method for an oil and gas reservoir, and belongs to the technical field of oil and gas reservoir development. After the acid fracturing fracture is formed, injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to ensure that the acid fracturing fracture cannot extend in the original transverse extending direction of the acid fracturing fracture; injecting into and thoughtlessly sealing the third fracturing fluid of particle, sealing and separating the particle and floating the top that plays the second fracturing fluid, avoid the acid fracturing crack to original horizontal extending direction and to fore-and-aft top extension. And finally, injecting a fourth fracturing fluid to mainly impact the lower surface of the acid fracturing fracture, continuously expanding the height of the acid fracturing fracture vertically downwards, and finally ensuring the transverse extension length of the acid fracturing fracture, effectively expanding the height of the acid fracturing fracture vertically, increasing the overall volume of the acid fracturing fracture, realizing good communication between the acid fracturing fracture and the reservoir both horizontally and vertically, and increasing the output of finally produced oil gas.
Description
Technical Field
The disclosure relates to the technical field of oil and gas reservoir development, in particular to an acid fracturing method for an oil and gas reservoir.
Background
Acid fracturing is the mainstream technology for yield increase modification of carbonate oil and gas reservoirs. During acid fracturing construction, a high-pressure pump injects fracturing fluid, and the fracturing fluid breaks natural fractures or breaks a reservoir stratum to form artificial fractures.
When acid fracturing is actually carried out, fracturing fluid usually extends forwards from the end part of the fracture along the direction of the fracture continuously, the height of the fracture is usually unchanged or smaller, the overall volume of the fracture is smaller, communication with a reservoir is limited, and finally produced oil gas output is not ideal.
Disclosure of Invention
The embodiment of the disclosure provides an acid fracturing method for an oil and gas reservoir, which can improve the volume of a fracture obtained by acid fracturing so as to increase the communication degree with the reservoir and improve the output of finally produced oil and gas. The technical scheme is as follows:
the embodiment of the disclosure provides an acid fracturing method for an oil and gas reservoir, which comprises the following steps:
injecting a first fracturing fluid into a formation of a hydrocarbon reservoir to form an acid fracture in the formation;
injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extending direction, wherein the transverse extending direction is parallel to the horizontal plane;
injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the density of the packing particles is less than that of the second fracturing fluid;
and injecting a fourth fracturing fluid into the acid fracturing fracture to longitudinally expand the acid fracturing fracture, wherein the longitudinal direction is the gravity direction.
Optionally, the total mass of the packing particles in the third fracturing fluid accounts for 0.8-1.2% of the total mass of the third fracturing fluid.
Optionally, the particle size of the packing particles is 2.75um to 3.67 um.
Optionally, the packing particles comprise at least one of hollow glass beads, phenol formaldehyde resin particles, quartz sand.
Optionally, the hydrocarbon reservoir acid fracturing method further comprises:
before injecting a fourth fracturing fluid into the acid fracturing fracture, 3m is added to the acid fracturing fracture3/min～4m3And injecting non-crosslinked fracturing fluid at the discharge capacity of/min.
Optionally, the temporary plugging agent is a mixture of a particle temporary plugging agent and a powder temporary plugging agent, the particle temporary plugging agent comprises at least one of soluble resin particles, water-soluble temporary plugging particles and oil-soluble temporary plugging particles, and the powder temporary plugging agent comprises at least one of soluble powdered resin, water-soluble powdered temporary plugging agent and oil-soluble powdered temporary plugging agent.
Optionally, the total mass of the temporary plugging agent in the second fracturing fluid accounts for 0.5-0.8% of the total mass of the second fracturing fluid.
Alternatively,
the step of injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extension direction comprises the following steps:
detecting the transverse extension length of the acid fracturing fracture;
and if the transverse extension length of the acid fracturing fracture reaches the target length, injecting a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extension direction.
Optionally, the injecting into the acid fracturing fracture a fourth fracturing fluid that longitudinally extends the acid fracturing fracture comprises:
and alternately injecting the fourth fracturing fluid and acid liquor into the acid fracturing fracture.
Optionally, the acid solution has a density of 1.3g/cm3～1.35g/cm3。
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure at least comprise:
after injecting first fracturing fluid into a stratum of an oil and gas reservoir and forming an acid fracturing fracture, injecting second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture, wherein the temporary plugging agent is carried by the second fracturing fluid to completely plug the end part of the acid fracturing fracture in the transverse extending direction, so that the acid fracturing fracture cannot continue to extend in the transverse direction; further injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the packing particles with the density smaller than that of the second fracturing fluid float to directly contact the uppermost part of the second fracturing fluid with the upper surface of the acid fracturing fracture under the action of buoyancy after entering the acid fracturing fracture, and separate the upper surface of the acid fracturing fracture from the fracturing fluid, so that the second fracturing fluid is prevented from impacting the upper surface of the acid fracturing fracture, the acid fracturing fracture is prevented from extending upwards in the transverse and longitudinal directions, finally, a fourth fracturing fluid for longitudinally expanding the acid fracturing fracture is injected into the acid fracturing fracture, the fourth fracturing fluid mainly impacts the lower surface of the acid fracturing fracture under the action of a temporary plugging agent and the packing particles, the height of the acid fracturing fracture is continuously expanded downwards in the longitudinal direction under the action of gravity, so that the height of the acid fracturing fracture is continuously increased in the longitudinal direction, and finally, the transverse extension length of the acid fracturing fracture is ensured, the height of the acid fracturing fracture in the longitudinal direction is effectively expanded, the overall volume of the acid fracturing fracture is increased, the acid fracturing fracture can be well communicated with a reservoir in the transverse direction and the longitudinal direction, and the output of finally produced oil gas can be increased.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a flow chart of a method for acid fracturing of a hydrocarbon reservoir provided by an embodiment of the present disclosure;
FIG. 2 is a flow chart of another method for acid fracturing of a hydrocarbon reservoir provided by an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of an acid fracturing process provided by embodiments of the present disclosure;
fig. 4 is a schematic diagram of another acid fracturing process provided by embodiments of the present disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," "third," and similar terms in the description and claims of the present disclosure are not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", "top", "bottom", and the like are used merely to indicate relative positional relationships, which may also change accordingly when the absolute position of the object being described changes.
Fig. 1 is a flow chart of an acid fracturing method for an oil and gas reservoir provided by an embodiment of the disclosure. As shown in fig. 1, the acid fracturing method for oil and gas reservoirs comprises the following steps:
s101: a first fracturing fluid is injected into a formation of a hydrocarbon reservoir to form an acid fracture in the formation.
S102: and injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extending direction.
Wherein the transverse extension direction is a transverse extension direction parallel to the horizontal plane.
S103: and injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the density of the packing particles is less than that of the second fracturing fluid.
S104: and injecting a fourth fracturing fluid into the acid fracturing fracture to longitudinally expand the acid fracturing fracture.
Wherein the longitudinal direction is the direction of gravity.
After injecting first fracturing fluid into a stratum of an oil and gas reservoir and forming an acid fracturing fracture, injecting second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture, wherein the temporary plugging agent is carried by the second fracturing fluid to completely plug the end part of the acid fracturing fracture in the transverse extending direction, so that the acid fracturing fracture cannot extend to the original transverse extending direction of the acid fracturing fracture; and further injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the packing particles with the density smaller than that of the second fracturing fluid can float to the uppermost part of the second fracturing fluid and directly contact the upper surface of the acid fracturing fracture due to the buoyancy effect after entering the acid fracturing fracture, and the upper surface of the acid fracturing fracture is separated from the fracturing fluid, so that the second fracturing fluid is prevented from impacting the upper surface of the acid fracturing fracture. Therefore, the acid fracturing fracture is prevented from extending towards the original transverse extending direction and the longitudinal upper side, finally, fourth fracturing fluid of the longitudinal extension acid fracturing fracture is injected into the acid fracturing fracture, the acting force of the fourth fracturing fluid on the temporary plugging agent and the packing particles can mainly impact the lower surface of the acid fracturing fracture, the height of the acid fracturing fracture can be continuously extended downwards in the longitudinal direction under the action of the combined gravity, the height of the acid fracturing fracture in the longitudinal direction is continuously increased, the transverse extending length of the acid fracturing fracture is finally ensured, the height of the acid fracturing fracture in the longitudinal direction is effectively increased, the integral volume of the acid fracturing fracture is increased, the acid fracturing fracture can be well communicated with a reservoir in the transverse direction and the longitudinal direction, and the output of finally-produced oil gas can be increased.
It should be noted that most reservoirs in a hydrocarbon reservoir are distributed transversely, so when the formation is subjected to acid fracturing, the ends of the acid fracturing fractures formed in the formation in the transverse direction are also generally transverse, and the fractures can be well communicated with the reservoirs distributed transversely, but can be lack of communication with a part of the reservoirs distributed longitudinally. According to the method, the height of the acid fracturing fracture in the longitudinal direction is enlarged, communication with the reservoirs in the transverse direction can be met, communication with part of the reservoirs in the longitudinal direction can be met, and the finally obtained oil gas output is increased.
In implementations provided by the present disclosure, the lateral direction is a horizontal direction, the longitudinal direction is a gravitational direction, and the lateral direction and the longitudinal direction are perpendicular to each other.
Fig. 2 is a flow chart of another acid fracturing method for a hydrocarbon reservoir provided by an embodiment of the present disclosure, as shown in fig. 2, the acid fracturing method for a hydrocarbon reservoir includes:
s201: a first fracturing fluid is injected into a formation of a hydrocarbon reservoir to form an acid fracture in the formation.
Alternatively, the first fracturing fluid may be a fracturing fluid incorporating a crosslinking agent.
The fracturing fluid doped with the cross-linking agent has higher viscosity, can more easily break the fracture, simultaneously keeps the fracture to have certain supporting capacity, and reduces the possibility of closing the acid fracturing fracture to a certain extent.
In one implementation provided by the present disclosure, the displacement of the first fracturing fluid may be 6m3/min～10m3/min。
The discharge capacity of the first fracturing fluid is in the range, the stratum can be stably flushed, and the volume of the finally obtained acid fracturing fracture is guaranteed.
For example, the first fracturing fluid may be introduced for 30 to 60 minutes. It is ensured that the resulting acid fracturing fracture can have a sufficient lateral extension.
Alternatively, the volume of the first fracturing fluid in step S201 may be 30% to 40% of the volume of all fluids required in the acid fracturing method of the hydrocarbon reservoir.
At the moment, the scale of the acid fracturing fracture formed firstly can be ensured, and the subsequent expansion of the acid fracturing fracture is ensured to be based on the acid fracturing fracture, while the possibility of directly forming a new acid fracturing fracture on the basis of the initial acid fracturing fracture is smaller.
S202: and injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extending direction.
In step S202, the temporary plugging agent may be a mixture of a granular temporary plugging agent and a powdered temporary plugging agent.
The temporary plugging agent is a mixture of the particle temporary plugging agent and the powder temporary plugging agent, can effectively plug the end part of the transverse extending direction of the acid fracturing fracture, is easier to degrade in the subsequent digestion process, avoids influencing the output of oil gas, and can ensure the subsequent stable output of the oil gas of the acid fracturing fracture.
Optionally, the mass ratio of the particle temporary plugging agent to the powder temporary plugging agent can be 3: 7-8: 2. The temporary plugging effect on the acid fracturing fracture can be ensured.
In one implementation provided by the present disclosure, the mass ratio of the particulate temporary plugging agent to the powder temporary plugging agent may also be 6: 4. The end part of the acid fracturing fracture in the transverse extending direction can be stably plugged, and the finally obtained acid fracturing fracture can be well communicated with a reservoir stratum.
Alternatively, the particle size of the particulate temporary plugging agent may be 0.14mm to 1.3 mm. At the moment, the acid fracturing fracture can be stably plugged.
In one implementation provided by the present disclosure, the particle size of the particulate temporary plugging agent may also be 1 mm. Can effectively block acid fracturing cracks.
Alternatively, the density of the particulate temporary plugging agent and the powder temporary plugging agent may be 65% to 80% of the density of the second fracturing fluid. Most of the temporary plugging agent can be pushed to the end part of the acid fracturing fracture by the second fracturing fluid, and the temporary plugging agent is basically not deposited on the lower surface of the acid fracturing fracture to influence the expansion of the fracture height of the acid fracturing fracture.
Illustratively, the particulate temporary plugging agent may include at least one of soluble resin particles, water-soluble temporary plugging particles and oil-soluble temporary plugging particles, and the powder temporary plugging agent may include at least one of soluble powdered resin, water-soluble powdered temporary plugging agent and oil-soluble powdered temporary plugging agent.
The particle temporary plugging agent and the powder temporary plugging agent are made of the above materials, so that the plugging effect can be ensured, the subsequent degradation is facilitated, and the formation efficiency of the acid fracturing crack is improved.
Optionally, the total mass of the temporary plugging agent in the second fracturing fluid can be 0.5-0.8% of the total mass of the second fracturing fluid.
Can keep the volume of acid fracturing crack simultaneously, will temporarily stifled agent stable promotion to the tip of acid fracturing crack, guarantee that the tip of the horizontal extending direction of acid fracturing crack can be stably stopped up by temporarily stifled agent.
The mass fraction of the temporary plugging agent in the second fracturing fluid is the sum of the mass fraction of the particle temporary plugging agent in the second fracturing fluid and the mass fraction of the powder temporary plugging agent in the second fracturing fluid.
Alternatively, the displacement of the second fracturing fluid may be 2m3/min～5m3/min。
The discharge capacity of the second fracturing fluid is in the range, so that the temporary plugging agent can be stably introduced into the acid fracturing fracture, and the volume of the finally obtained acid fracturing fracture is ensured.
For example, the second fracturing fluid may be introduced for a period of time ranging from 20min to 40 min.
The time for introducing the second fracturing fluid is in the range, so that the second fracturing fluid can be ensured to carry enough temporary plugging agent to enter the acid fracturing fracture, and the plugging effect on the acid fracturing fracture is ensured.
In step S202, 2m may be adopted first3Injecting a second fracturing fluid carrying a temporary plugging agent at a low discharge rate of/min, and increasing the discharge rate of the second fracturing fluid to 4m3/min～5m3And/min, so as to push the temporary plugging agents to the end part of the transverse extension of the acid fracturing fracture, and promote the end part of the transverse extension of the acid fracturing fracture to be close to a state of being filled with the temporary plugging agents. The transverse acid fracturing crack can be completely avoidedAnd the extension condition is generated, so that the acid fracturing fracture can stably extend in the longitudinal direction after the fracturing fluid is introduced subsequently.
Alternatively, the second fracturing fluid may also be a fracturing fluid incorporating a crosslinking agent.
The second fracturing fluid is also doped with a cross-linking agent, so that on one hand, the temporary plugging agent can be more conveniently injected into the acid fracturing fracture, and on the other hand, the second fracturing fluid and the temporary plugging agent can also counteract the closing pressure of the acid fracturing fracture to a certain extent, so that the possibility of closing the acid fracturing fracture is reduced.
In step S202, when the lateral extension length of the acid fracturing fracture reaches the target lateral extension length, a temporary plugging agent may be injected into the acid fracturing fracture to plug the end of the acid fracturing fracture in the lateral extension direction.
When the transverse extension length of the acid fracturing fracture reaches the target transverse extension length, the temporary plugging agent is introduced, so that the effective communication capacity between the acid fracturing fracture and a transverse reservoir is ensured, and when the acid fracturing fracture is further expanded, the longitudinal expansion of the acid fracturing fracture can be mainly focused. The transverse length and the longitudinal height of the finally obtained acid fracturing fracture are ensured to be larger, effective communication between the transverse reservoir and the longitudinal reservoir can be realized, and the finally obtained oil gas output is also higher.
Alternatively, the lateral extension length of the acid fracturing fracture may be monitored in real time using downhole microseismic monitoring techniques.
The transverse extension length of the acid fracturing fracture is monitored in real time by using an underground micro-seismic monitoring technology, the real-time length of the acid fracturing fracture can be observed at the end part, the second fracturing fluid and the temporary plugging agent are timely introduced when the transverse extension length of the acid fracturing fracture reaches the target transverse extension length, and the stable plugging of the acid fracturing fracture is guaranteed.
It should be noted that the target lateral extension length of the acid fracturing fracture can be determined and adjusted according to the distribution of the reservoir. The distribution of the reservoir may then be obtained from seismic exploration equipment.
For the convenience of understanding, fig. 3 and 4 may be provided, fig. 3 is a schematic diagram of an acid fracturing process provided by an embodiment of the present disclosure, and a view angle in fig. 3 is a cross-sectional view of an acid fracturing fracture taken parallel to a horizontal plane, as can be seen with reference to fig. 3, when the ends of the acid fracturing fracture 1 in the transverse direction are all filled with the temporary plugging agent 2, the temporary plugging agent 2 prevents the fracturing fluid from impacting the acid fracturing fracture 1 in the transverse direction of the acid fracturing fracture 1, so that the acid fracturing fracture 1 is prevented from further extending in the transverse direction, and when the fracturing fluid is subsequently introduced into the acid fracturing fracture 1, the acid fracturing fracture 1 is only extended in the longitudinal direction.
Fig. 4 is a schematic diagram of another acid fracturing process provided by the embodiment of the present disclosure, and the view angle in fig. 4 is a cross-sectional view of an acid fracturing fracture taken in a parallel vertical direction, as can be seen from fig. 4, a fracturing fluid can enter the acid fracturing fracture from a perforation 3, and the transverse direction and the upper surface of the acid fracturing fracture 1 are respectively filled with a temporary plugging agent 2 and packing particles 4, so that when the fracturing fluid is continuously introduced, the acid fracturing fracture 1 is impacted and enlarged by the fracturing fluid in the longitudinal direction. In fig. 3 and 4, the transverse direction is the x direction and the longitudinal direction is the y direction.
Fig. 3 is a cross-sectional view of only one acid fracturing fracture in fig. 4. And fig. 3 and 4 are provided by way of example for perforation acid fracturing, but in other implementations provided by the present disclosure, the manner of acid fracturing the formation may be other manners, and the present disclosure is not limited thereto.
S203: and injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the density of the packing particles is less than that of the second fracturing fluid.
Optionally, the ratio of the density of the packing particles to the density of the second fracturing fluid is 0.4-0.7.
When the ratio of the density of the packing particles to the density of the second fracturing fluid is within the range, the packing particles can float along with the second fracturing fluid for a period of time after entering the acid fracturing fracture, and the packing particles can be guaranteed to be distributed on the upper surface of the acid fracturing fracture relatively uniformly.
In step S203, the total mass of the third fracturing fluid may be 0.8 to 1.2% of the total mass of the third fracturing fluid.
The mass fraction of the packing particles in the third fracturing fluid is in the above range, so that the third fracturing fluid can be ensured to carry enough packing particles into the acid fracturing fracture, and the packing particles can effectively pack the upper surface of the acid fracturing fracture.
Illustratively, the density of the packing particles in the third fracturing fluid may be 0.5g/cm3～0.7g/cm3。
The density of the packing particles in the third fracturing fluid is within the range, so that the density of the packing particles on the upper surface of the final acid fracturing fracture can be guaranteed not to be too high, and the contact between the upper surface of the acid fracturing fracture and the fracturing fluid can be effectively blocked.
Alternatively, the particle size of the packing particles may be 2.75um to 3.67 um.
The particle size of packing the granule is in above the within range, can be convenient for carry by the third fracturing fluid get into the acid fracturing crack in, and pack and separate the granule and also can block in the partial pit of establishing in the acid fracturing crack, effectively reduce fracturing fluid and acid fracturing crack's upper surface and contact, guarantee that the lower surface of acid fracturing crack can be stably strikeed and the extension by fracturing fluid.
Illustratively, the packing particles may include at least one of hollow glass beads, phenol formaldehyde resin particles, 100-mesh 200-mesh quartz sand.
When the material of the packing particles is the material, on one hand, the material is easy to obtain, and on the other hand, the packing particles are also convenient to digest.
In one implementation provided by the present disclosure, the packing particles may be hollow glass beads.
The fracturing fluid is easy to obtain, low in cost and capable of quickly floating from the third fracturing fluid.
In step S203, the discharge amount of the third fracturing fluid may be 4m3/min～6m3/min。
The discharge capacity of the third fracturing fluid is in the range, the packing particles can be stably introduced into the acid fracturing fracture, and the volume of the finally obtained acid fracturing fracture is ensured.
Illustratively, the time period for the third fracturing fluid to be introduced can be 30-50 min.
The time for introducing the third fracturing fluid is in the range, so that the third fracturing fluid can be ensured to carry enough packing particles to enter the acid fracturing fracture, and the effect of plugging the acid fracturing fracture is ensured.
Alternatively, the third fracturing fluid may also be a fracturing fluid incorporating a crosslinking agent. Facilitating carrying the packing particles only into the acid fracturing fracture.
S204: to acid fracturing crack at 3m3/min～4m3/And (4) injecting non-crosslinked fracturing fluid at the discharge capacity of min.
In addition, no crosslinking agent is added to the non-crosslinked fracturing fluid.
After injection of the packing particles, 3m3/min～4m3/And (4) injecting non-crosslinked fracturing fluid into the acid fracturing fracture at the discharge capacity of min, wherein the non-crosslinked fracturing fluid with lower discharge capacity can not cause larger pressure to the acid fracturing fracture. And the viscosity and density of the non-crosslinked fracturing fluid are lower than those of the fracturing fluid doped with the crosslinking agent, and the packing particles can be stirred, so that the packing particles in the acid fracturing fracture are more uniformly distributed, and the condition that part of the acid fracturing fracture is contacted with the fracturing fluid due to nonuniform distribution of the packing particles is reduced.
Alternatively, the acid fracturing may be performed at 3m3/min～4m3/And injecting the non-crosslinked fracturing fluid for 10-15 min at the discharge capacity of min.
At the moment, the time of the injected non-crosslinked fracturing fluid is sufficient, and the packing particles are more uniformly distributed under the driving of the non-crosslinked fracturing fluid.
S205: and injecting a fourth fracturing fluid for longitudinally expanding the acid fracturing fracture into the acid fracturing fracture.
After the steps are completed, the fourth fracturing fluid can be directly introduced into the acid fracturing fracture and acts on the acid fracturing fracture mainly along the longitudinal downward direction, so that the height of the acid fracturing fracture can be stably enlarged.
In step S205, the fourth fracturing fluid may be a fracturing fluid doped with a crosslinking agent. The height of the crack can be more effectively extended.
Illustratively, step S205 may include: and alternately injecting a fourth fracturing fluid and acid liquor into the acid fracturing fracture.
And the fourth fracturing fluid and the acid liquor are alternately injected into the acid fracturing crack, so that the effects of the fracturing fluid and the acid liquor can be superposed, the acid fracturing crack is hydraulically fractured, and the acid liquor performs acid etching on the surface of the acid fracturing crack, so that the oil gas can smoothly flow in the acid fracturing crack, and the output of the oil gas is finally improved. When the fourth fracturing fluid is doped with the cross-linking agent, the fourth fracturing fluid can fill and level pits on the surface of the acid fracture, so that the surface of the acid fracture can be more smooth.
For example, the fourth fracturing fluid may alternate with the acid fluid twice. The acid fracturing crack with a smooth surface and good expansion can be obtained.
Alternatively, the fourth fracturing fluid may have a displacement of 6m3/min～9m3/min。
The discharge capacity of the fourth fracturing fluid is in the range, so that the acid fracturing fracture can be effectively expanded, and the volume of the finally obtained acid fracturing fracture is ensured.
Illustratively, the time period for the fourth fracturing fluid to be introduced can be 40min to 60 min.
The introduction time of the fourth fracturing fluid is in the range, so that the fourth fracturing fluid can be ensured to effectively expand the acid fracturing fracture, and the finally obtained volume of the acid fracturing fracture is ensured.
Alternatively, the displacement of acid liquor may be 6m3/min～9m3/min。
The discharge capacity of the acid liquor is in the range, so that the net pressure in the acid fracturing fracture can be effectively increased, and the expansion and support of the acid fracturing fracture are guaranteed.
Illustratively, the time period for introducing the acid solution can be 30min to 50 min.
The time for introducing the acid liquor is in the range, so that the net pressure in the acid fracturing fracture can be effectively increased, and the expansion and support of the acid fracturing fracture are ensured.
Illustratively, the acid solution may have a density of 1.3g/cm3～1.35g/cm3。
The acid solution has a density of 1.1g/cm relative to conventional acid solution in the above range3The acid liquor can effectively improve the net pressure in the acid fracturing crack and ensure the volume of the finally obtained acid liquor crack.
In one implementation provided by the present disclosure, the acid solution may include hydrochloric acid, a weighting agent, a gelling agent, a corrosion inhibitor, an iron ion stabilizer, a cleanup additive, and a clay stabilizer.
The acid liquor adopting the formula can effectively improve the net pressure in the acid fracturing fracture and promote the acid fracturing fracture to be easier to open.
In another implementation provided by the present disclosure, an acid solution may include: 20.0% hydrochloric acid, 55% weighting agent, 0.05% gelling agent, 1.0% corrosion inhibitor, 2.0% iron ion stabilizer, 1.0% cleanup additive and 1.0% clay stabilizer. The weighted acid has a density of 1.3g/cm3～1.35g/cm3. The volume of the acid fracturing crack obtained finally is large.
S206: and (4) introducing slickwater into the acid fracturing fracture to replace liquid in the acid fracturing fracture.
It should be noted that after step S06 is completed, when no external liquid such as fracturing fluid is introduced into the acid fracturing fracture, the temporary plugging agent will be gradually degraded by the high temperature in the formation, so that the temporary plugging agent will not affect the production of oil and gas in the subsequent reservoir, and the packing particles will be accumulated in the formation, and will not affect the production of oil and gas in the subsequent reservoir.
For ease of understanding, one implementation of the present disclosure may be described herein with X oilfield a-well as the application of the acid fracturing method, the reservoir depth of the a-well is 6160m, which belongs to the carbonate gas reservoir vertical well, and there are two dominant reservoirs at a distance of 116m laterally from the wellbore of the a-well and 86m longitudinally from the bottom of the well. The steps can be as follows:
into the formation with a displacement of 7.5m3The injection volume is 300 m/min3The first fracturing fluid forms an acid fracturing fracture, and the first fracturing fluid is doped with a cross-linking agent;
injecting a temporary plugging agent with the mass ratio of 0.8% into the stratum, wherein the volume of the temporary plugging agent is 100m3The second fracturing fluid is doped with a cross-linking agent, the temporary plugging agent comprises a particle temporary plugging agent and a powder temporary plugging agent, the particle size of the particle temporary plugging agent is 1mm, and the mass ratio of the particle temporary plugging agent to the powder temporary plugging agent is 6: 4;
injecting hollow glass beads carrying 1.0% by mass into the stratum, wherein the volume of the hollow glass beads is 100m3The third fracturing fluid is doped with a cross-linking agent, the tendency of acid fracturing fracture to extend upwards is reduced, and particles are injectedHollow glass beads with the diameter of 2.75 um-3.67 um, and the density of the glass beads is 0.5g/cm3～0.7g/cm3And the injection displacement of the third fracturing fluid is 4m3/min；
Into the formation with a displacement of 4m3Injecting non-crosslinked fracturing fluid for 15 min/min, so that the hollow glass beads float upwards to form effective packing;
respectively and alternately injecting a fourth fracturing fluid and an acid solution twice into the stratum, wherein the fourth fracturing fluid is a fracturing fluid doped with a cross-linking agent, and the discharge capacity of the injected fourth fracturing fluid is 8m3Min, the discharge capacity of the injected acid liquid is 7m3/min；
The length of the transverse seam of the finally obtained acid fracturing fracture is half 124m, the height of the longitudinal seam is half 93m or so, and the purpose of longitudinal and transverse bidirectional deep penetration acid fracturing is achieved.
In the embodiments provided by the present disclosure, both the fracturing fluid and the acid solution may be injected into the formation through the oil pipe, and in other implementations provided by the present disclosure, the fracturing fluid and the acid solution may also be injected into the formation through other manners, which is not limited by the present disclosure.
The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.
Claims (10)
1. An acid fracturing method for an oil and gas reservoir, which comprises the following steps:
injecting a first fracturing fluid into a formation of a hydrocarbon reservoir to form an acid fracture in the formation;
injecting a second fracturing fluid mixed with a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extending direction, wherein the transverse extending direction is parallel to the horizontal plane;
injecting a third fracturing fluid mixed with packing particles into the acid fracturing fracture, wherein the density of the packing particles is less than that of the second fracturing fluid;
and injecting a fourth fracturing fluid into the acid fracturing fracture to longitudinally expand the acid fracturing fracture, wherein the longitudinal direction is the gravity direction.
2. The acid fracturing method of an oil and gas reservoir according to claim 1, wherein the total mass of the packer particles in the third fracturing fluid accounts for 0.8-1.2% of the total mass of the third fracturing fluid.
3. The hydrocarbon reservoir acid fracturing method of claim 1, wherein the packing particles have a particle size of 2.75um to 3.67 um.
4. The acid fracturing method of oil and gas reservoirs according to any one of claims 1 to 3, wherein the packing particles comprise at least one of hollow glass beads, phenol formaldehyde resin particles and quartz sand.
5. The hydrocarbon reservoir acid fracturing method of any one of claims 1 to 3, further comprising:
before injecting a fourth fracturing fluid into the acid fracturing fracture, 3m is added to the acid fracturing fracture3/min～4m3And injecting non-crosslinked fracturing fluid at the discharge capacity of/min.
6. The acid fracturing method for oil and gas reservoirs according to any one of claims 1 to 3, wherein the temporary plugging agent comprises a particle temporary plugging agent and a powder temporary plugging agent, the particle temporary plugging agent comprises at least one of soluble resin particles, water-soluble temporary plugging particles and oil-soluble temporary plugging particles, and the powder temporary plugging agent comprises at least one of soluble powdered resin, water-soluble powdered temporary plugging agent and oil-soluble powdered temporary plugging agent.
7. The acid fracturing method for oil and gas reservoirs according to any one of claims 1 to 3, wherein the total mass of the temporary plugging agent in the second fracturing fluid accounts for 0.5 to 0.8 percent of the total mass of the second fracturing fluid.
8. The oil and gas reservoir acid fracturing method according to any one of claims 1 to 3, wherein the injecting of the second fracturing fluid mixed with the temporary plugging agent into the acid fracturing fracture to plug the end of the acid fracturing fracture in the transverse extension direction comprises:
detecting the transverse extension length of the acid fracturing fracture;
and if the transverse extension length of the acid fracturing fracture reaches the target length, injecting a temporary plugging agent into the acid fracturing fracture to plug the end part of the acid fracturing fracture in the transverse extension direction.
9. The oil and gas reservoir acid fracturing method of any one of claims 1 to 3, wherein the injecting of the fourth fracturing fluid into the acid fracturing fracture to longitudinally expand the acid fracturing fracture comprises:
and alternately injecting the fourth fracturing fluid and acid liquor into the acid fracturing fracture.
10. The hydrocarbon reservoir acid fracturing method of claim 9, wherein the acid solution has a density of 1.3g/cm3～1.35g/cm3。
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