A fracturing method for realizing three-dimensional reconstruction of compact longitudinal multi-lithologic reservoirs

Abstract

The application discloses a fracturing method for realizing three-dimensional reconstruction of compact longitudinal multi-lithologic reservoirs, and specifically comprises the following steps: step 1, perforating near the sand-mud and sand-shale interface position; step 2, starting volume fracturing construction at the perforation in step 1, injecting preflush into the perforation, making the formation crack and forming an artificial formation fracture; step 3, adopting a sand-carrying fluid to carry different particle size proppant and pulse type circulation alternately injecting into the formation fracture in step 2; and step 4, injecting displacement fluid into the formation fracture, closing the well, releasing and producing. The method adopts large-displacement high-low viscosity liquid circulation fracturing and multi-particle size proppant pulse type alternate sanding method, and realizes three-dimensional full reconstruction of the multi-lithologic reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil production engineering, and relates to a fracturing method for realizing three-dimensional reconstruction of a tight vertical multi-lithology reservoir. BACKGROUND

[0002] The tight reservoir has the characteristics of poor physical property and vertically interbedded sand-shale and shale, and a large-scale volume fracturing is used to increase the reservoir reconstruction volume. The existing reconstruction technology mainly adopts volume fracturing characterized by multi-cluster perforation, large displacement and large liquid volume, and is matched with low-viscosity fracturing fluid and combined particle size proppant (mainly combined with 20 / 40 mesh and 40 / 70 mesh), and has the following main problems: the hydraulic fracture size difference is large, the natural fractures opened by the volume fracturing and the shear fractures formed are narrow, the large particle size proppant is difficult to enter the support, the proppant is difficult to be completely filled, and the three-dimensional reconstruction is difficult (the actually measured three-dimensional reconstruction degree is only about 35%). SUMMARY

[0003] The present application aims to provide a fracturing method for realizing three-dimensional reconstruction of a tight vertical multi-lithology reservoir, which realizes full three-dimensional reconstruction of the multi-lithology reservoir by adopting large-displacement high-low-viscosity liquid circulation fracturing and multi-particle size proppant pulse type alternate sand adding method.

[0004] The technical scheme adopted by the present application is a fracturing method for realizing three-dimensional reconstruction of a tight vertical multi-lithology reservoir, which specifically comprises the following steps:

[0005] Step 1: perforating near the sand-shale and sand-shale interface position;

[0006] Step 2: starting volume fracturing construction at the perforation in step 1, injecting preflush into the perforation to make the formation crack and form an artificial formation fracture;

[0007] Step 3: adopting sand-carrying fluid to carry different particle size proppants and pulse type circulation alternately injecting into the formation fracture in step 2;

[0008] Step 4: injecting displacement fluid into the formation fracture, closing the well, blowing and producing.

[0009] The present application has the following characteristics:

[0010] In step 1, the perforation adopts a multi-section equal-cluster perforation mode.

[0011] In step 1, the length of each section of the perforation is 1-2 meters, and the cluster number of the perforation is greater than 5 clusters.

[0012] In step 2, the preflush is injected at a low displacement, and the low displacement range is 1.5-3.0 m 3 / min.

[0013] In step 3, the sand-carrying fluid is high-displacement injection, and the high-displacement range is 5.0-8.0 m 3 / min.

[0014] In step 2, the preflush is a high-viscosity fracturing fluid.

[0015] In step 3, the sand-carrying fluid is a low-viscosity slick water fracturing fluid and a high-viscosity fracturing fluid.

[0016] The displacement fluid is a low-viscosity slick water fracturing fluid.

[0017] The low-viscosity slick water fracturing fluid comprises a drag-reducing agent and shale / mudstone inhibitors; and the high-viscosity fracturing fluid comprises a drag-reducing agent and a thickening agent.

[0018] The method provided by the application can solve the problem of low stereoscopic reconstruction degree of the existing volume fracturing. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a high-low viscosity fluid circulation fracturing and multi-particle size proppant pulse type alternate sand fracturing schematic diagram provided in embodiment 1 of the fracturing method for realizing stereoscopic reconstruction of the dense longitudinal multi-lithology reservoir.

[0020] Figure 2 is a high-low viscosity fluid circulation fracturing and multi-particle size proppant pulse type alternate sand fracturing schematic diagram provided in embodiment 2 of the fracturing method for realizing stereoscopic reconstruction of the dense longitudinal multi-lithology reservoir.

[0021] Figure 3 is a high-low viscosity fluid circulation fracturing and multi-particle size proppant pulse type alternate sand fracturing schematic diagram provided in embodiment 3 of the fracturing method for realizing stereoscopic reconstruction of the dense longitudinal multi-lithology reservoir.

[0022] Figure 4 is a high-low viscosity fluid circulation fracturing and multi-particle size proppant pulse type alternate sand fracturing schematic diagram provided in embodiment 4 of the fracturing method for realizing stereoscopic reconstruction of the dense longitudinal multi-lithology reservoir. DETAILED DESCRIPTION

[0023] The application will be described in detail below with reference to the drawings and specific embodiments.

[0024] The application discloses a fracturing method for realizing three-dimensional reconstruction of a compact longitudinal multi-lithologic reservoir.

[0025] Step 1, a plurality of equal-cluster perforation segments are arranged near (within 1 m from a sand-mud interface or a sand-shale interface) the sand-mud interface or the sand-shale interface.

[0026] The perforation is in a plurality of equal-cluster perforation modes, the number of perforation clusters is generally greater than 5 clusters, the length of the perforation segment is 1-2 m, the perforation density is 16 holes / m, and the perforation phase is 60°.

[0027] Step 2, starting volume fracturing construction, using high-viscosity fracturing fluid as a preflush to inject at a low rate to make the formation crack and form a certain length of artificial fracture.

[0028] In step 2, the preflush is injected at a low rate, and the low rate is 1.5-3.0 m 3 / min.

[0029] Step 3, the sand-carrying fluid is high-rate low-viscosity slick water fracturing fluid and high-viscosity fracturing fluid, and different particle size proppants are carried into the formation fracture, in the sand-carrying fluid construction process, the low-viscosity slick water fracturing fluid carries small particle size proppants (the proppants are 70 / 140 mesh quartz sand), the high-viscosity fracturing fluid carries large particle size proppants (the proppants are 20 / 40 mesh quartz sand or 40 / 70 mesh quartz sand), and the different particle size proppants are injected in a pulse mode, so that the effective propped fracture length is improved. Figure 1 The sand-carrying fluid is injected at a high rate, and the high rate is 5.0-8.0 m 3 / min.

[0030] Step 4, using low-viscosity slick water fracturing fluid as a displacement fluid to displace the sand-carrying fluid into the formation, wherein the amount of the displacement fluid is equivalent to the volume of the construction pipe column.

[0031] The main formula of the low-viscosity slick water fracturing fluid is resistance-reducing agent+shale / mudstone inhibitor, and the main formula of the high-viscosity fracturing fluid is resistance-reducing agent+thickening agent.

[0032] The proppants are mainly and, which can better support different scale fractures.

[0033] The low-viscosity slick water fracturing fluid and the high-viscosity fracturing fluid cyclically carry different particle size proppants, and the single cycle time of the high-low viscosity fracturing is 5-10 minutes.

[0034] Step 5, shutting down for 30 minutes, releasing and producing, and shutting down for 30 minutes is to force the formation fracture to close.

[0035] Embodiment 1

[0036] A fracturing method for realizing three-dimensional reconstruction of a compact longitudinal multi-lithologic reservoir is operated according to the following construction steps.

[0037] Step 1, multiple cluster holes are drilled near the sand-mud, sand-shale interface; in step 1, the perforation is performed by using the multiple cluster perforation mode, the number of perforation clusters is 10, the perforation segment length is 1 meter, the perforation density is 16 holes per meter, and the perforation phase is 60°.

[0038] Step 2, the volume fracturing construction is started, a certain amount of high-viscosity fracturing fluid is used as a preflush to be injected at a low rate to make the formation crack and form a certain length of artificial fracture, as shown in Figure 1 ; in step 2, the preflush is injected at a low rate, and the low rate is 2.5 m 3 / min.

[0039] Step 3, the sand-carrying fluid is used to circulate the high-viscosity fracturing fluid and the high-viscosity fracturing fluid to carry different particle size proppants into the formation fracture, as shown in Figure 1 ; in step 3, the sand-carrying fluid is injected at a high rate, and the high rate is 6.0 m 3 / min.

[0040] Step 4, in the sand-carrying fluid construction process, the low-viscosity slick water fracturing fluid is used to carry smaller particle size proppants, and the high-viscosity fracturing fluid is used to carry larger particle size proppants, and the different particle size proppants are injected in a pulse mode, as shown in Figure 1 ;

[0041] Step 5, the low-viscosity slick water fracturing fluid is used to displace the sand-carrying fluid into the formation, and the amount of the displacement fluid is equivalent to the volume of the construction pipe column.

[0042] Step 6, the well is closed for 30 minutes, and the blowout and production are obtained.

[0043] The high-viscosity fracturing fluid and the low-viscosity slick water fracturing fluid used in steps 2, 3, 4 and 5 are mainly composed of a friction reducer and a shale / mudstone inhibitor, and the high-viscosity fracturing fluid is mainly composed of a friction reducer and a thickening agent.

[0044] The proppants used in the fracturing in steps 3 and 4 are mainly 20 / 40 mesh quartz sand, 40 / 70 mesh quartz sand and 70 / 140 mesh quartz sand, which can better support different scale fractures. In step 3, the low-viscosity slick water fracturing fluid and the high-viscosity fracturing fluid circulate to carry different particle size proppants, and the single circulation time of the high and low viscosity fracturing is 10 minutes. In step 4, the different particle size proppants are injected in a pulse mode, which can improve the effective propped fracture length.

[0045] In step 6, the well is closed for 30 minutes to force the fracture to close.

[0046] Example 2

[0047] The embodiment provides a fracturing method for realizing three-dimensional reconstruction of a tight vertical multi-lithologic reservoir, and the fracturing method is operated according to the following construction steps:

[0048] Step 1, multiple cluster holes are drilled near the sand-mud, sand-shale interface; the multiple cluster holes are drilled in step 1, the number of clusters is 8, the length of the hole is 1.5 meters, the density of the hole is 16 holes per meter, and the phase of the hole is 60°.

[0049] Step 2, the volume fracturing operation is started, a certain amount of high-viscosity fracturing fluid is used as a preflush to inject at a low rate to make the formation crack and form a certain length of artificial fracture, as shown in Figure 2 ; the preflush is injected at a low rate in step 2, the low rate is 1.5 m 3 / min.

[0050] Step 3, the sand-carrying fluid uses high-rate low-viscosity slickwater fracturing fluid and high-viscosity fracturing fluid to carry different particle size proppants into the formation fracture, as shown in Figure 2 ; the sand-carrying fluid is injected at a high rate in step 3, the high rate is 5.0 m 3 / min.

[0051] Step 4, during the sand-carrying fluid operation, low-viscosity slickwater fracturing fluid is used to carry smaller particle size proppants, and high-viscosity fracturing fluid is used to carry larger particle size proppants, and different particle size proppants are injected in a pulse mode, as shown in Figure 2 ;

[0052] Step 5, low-viscosity slickwater fracturing fluid is used to displace the sand-carrying fluid into the formation, and the amount of the displacement fluid is equivalent to the volume of the operation string;

[0053] Step 6, shut-in for 30 minutes, blowout and production.

[0054] The high-viscosity fracturing fluid and the low-viscosity slickwater fracturing fluid used in steps 2, 3, 4 and 5, the main formula of the low-viscosity slickwater fracturing fluid is friction reducer + shale / mudstone inhibitor, and the main formula of the high-viscosity fracturing fluid is friction reducer + thickening agent. The proppants used in steps 3 and 4 for fracturing are mainly 20 / 40 mesh quartz sand and 70 / 140 mesh quartz sand, which can better support cracks of different sizes.

[0055] The low-viscosity slickwater fracturing fluid and the high-viscosity fracturing fluid in step 3 carry different particle size proppants, and the single circulation time of the high and low viscosity fracturing is 8 minutes. In step 4, different particle size proppants are injected in a pulse mode, which can improve the effective propped fracture length. In step 6, the well is shut in for 30 minutes to force the fracture to close.

[0056] Example 3

[0057] A fracturing method for realizing three-dimensional reconstruction of dense vertical multi-lithology reservoirs is operated according to the following operation steps:

[0058] Step 1, multiple cluster perforation near the sand shale and sand shale interface; the perforation in step 1 is performed by using multiple cluster perforation, the number of perforation clusters is 6, the perforation length is 2 meters, the perforation density is 16 holes per meter, and the perforation phase is 60°.

[0059] Step 2, starting volume fracturing construction, a certain amount of high viscosity fracturing fluid is used as a preflush to be injected at a low rate to make the formation crack and form a certain length of artificial fracture, as shown in Figure 3 ; in step S2, the preflush is injected at a low rate, and the low rate is 3.0 m 3 / min.

[0060] Step 3, the sand-carrying fluid is used to circulate different particle size proppants into the formation fracture by using high rate and low viscosity slick water fracturing fluid and high viscosity fracturing fluid, as shown in Figure 3 ; in step 3, the sand-carrying fluid is injected at a high rate, and the high rate is 8.0 m 3 / min.

[0061] Step 4, in the process of sand-carrying fluid construction, the low viscosity slick water fracturing fluid is used to carry smaller particle size proppants, and the high viscosity fracturing fluid is used to carry larger particle size proppants, and the different particle size proppants are injected in a pulse mode, as shown in Figure 3 ;

[0062] Step 5, the low viscosity slick water fracturing fluid is used to displace the sand-carrying fluid into the formation, and the amount of the displacement fluid is equivalent to the volume of the construction string;

[0063] Step 6, shut-in for 30 minutes, blowout and production.

[0064] The high viscosity fracturing fluid and the low viscosity slick water fracturing fluid used in steps 2, 3, 4 and 5 are mainly composed of friction reducer + shale / mudstone inhibitor, and the high viscosity fracturing fluid is mainly composed of friction reducer + thickening agent.

[0065] The proppants used in steps 3 and 4 for fracturing are mainly 20 / 40 mesh quartz sand and 40 / 70 mesh quartz sand, which can better support different scale fractures.

[0066] In step 3, the low viscosity slick water fracturing fluid and the high viscosity fracturing fluid circulate to carry different particle size proppants, and the single circulation time of the high and low viscosity fracturing is 7 minutes. In step 4, the different particle size proppants are injected in a pulse mode, which can improve the effective propped fracture length. In step 6, the shut-in for 30 minutes is to force the fracture to close.

[0067] Example 4

[0068] A fracturing method for realizing three-dimensional reconstruction of dense vertical multi-lithologic reservoirs is operated according to the following construction steps:

[0069] Step 1, multiple cluster holes are drilled near the sand-mud, sand-shale interface; in step 1, the perforation is performed by using the multiple cluster perforation method, the number of perforation clusters is 9, the perforation segment length is 1 meter, the perforation density is 16 holes per meter, and the perforation phase is 60°.

[0070] Step 2, the volume fracturing construction is started, a certain amount of high-viscosity fracturing fluid is used as a preflush to be injected at a low rate to make the formation crack and form a certain length of artificial fracture, as shown in Figure 4 ; in step 2, the preflush is injected at a low rate, and the low rate is 2.0 m 3 / min.

[0071] Step 3, the sand-carrying fluid is used to circulate the different particle size proppants into the formation fracture by using the high-rate low-viscosity slick water fracturing fluid and the high-viscosity fracturing fluid, as shown in Figure 4 ; specifically, in step 3, the sand-carrying fluid is injected at a high rate, and the high rate is 6.0 m 3 / min.

[0072] Step 4, in the sand-carrying fluid construction process, the low-viscosity slick water fracturing fluid is used to carry the smaller particle size proppants, and the high-viscosity fracturing fluid is used to carry the larger particle size proppants, and the different particle size proppants are injected in a pulse mode, as shown in Figure 4 ;

[0073] Step 5, the low-viscosity slick water fracturing fluid is used to displace the sand-carrying fluid into the formation, and the amount of the displacement fluid is equivalent to the volume of the construction string;

[0074] Step 6, the well is closed for 30 minutes, the blowout is released, and the production is obtained.

[0075] Specifically, in steps 2, 3, 4, and 5, the high-viscosity fracturing fluid and the low-viscosity slick water fracturing fluid are used, and the main formula of the low-viscosity slick water fracturing fluid is friction reducer + shale / mudstone inhibitor, and the main formula of the high-viscosity fracturing fluid is friction reducer + thickening agent.

[0076] In steps 3 and 4, the proppants used for fracturing are mainly 40 / 70 mesh quartz sand and 70 / 140 mesh quartz sand, which can better support different scale fractures. In step 3, the low-viscosity slick water fracturing fluid and the high-viscosity fracturing fluid are used to circulate the different particle size proppants, and the single circulation time of the high and low viscosity fracturing is 5 minutes. In step 4, the different particle size proppants are injected in a pulse mode, which can improve the effective propped fracture length. In step 6, the well is closed for 30 minutes to force the fracture to close.

Claims

1. A method of fracturing to achieve a three-dimensional modification of a tight, vertical, multi-lithology reservoir, characterized in that: Specifically comprising the following steps: Step 1, perforating near the sand-mud interface and sand-shale interface; In the step 1, the perforating is in the form of multi-section equal-cluster perforating; In the step 1, the length of each section of the perforating is 1-2 meters, and the cluster number of the perforating is greater than 5 clusters; Step 2, starting volume fracturing construction at the perforation in step 1, injecting preflush into the perforation, making the formation crack and creating artificial formation cracks; in the step 2, the preflush is injected at a low rate, the low rate range is 1.5-3.0 m 3 / min; Step 3, injecting the main fracturing fluid into the perforation, the main fracturing fluid is injected at a high rate, the high rate range is 3.0-5.0 m 3 / min; Step 3, pulse circulation of different particle size proppant carried by the sand-carrying fluid is injected into the fractures in step 2 alternately; in the step 3, the sand-carrying fluid is injected at a high flow rate, and the high flow rate ranges from 5.0 to 8.0 m 3 / min. Step 4, pulse circulation of different particle size proppant carried by the sand-carrying fluid is injected into the fractures in step 2 alternately; in the step 4, the sand-carrying fluid is injected at a high flow rate, and the high flow rate ranges from 5.0 to 8.0 m 3 / min. Step 5, Step 4, injecting a displacement fluid into the formation fracture, closing the well, releasing and producing.

2. The method of claim 1, wherein the method is characterized by: In the step 2, the preflush is high-viscosity fracturing fluid.

3. The method of claim 2, wherein the method is characterized by: In the step 3, the sand-carrying fluid is low-viscosity slickwater fracturing fluid and high-viscosity fracturing fluid.

4. The method of claim 3, wherein the method is characterized by: The displacement fluid is low-viscosity slickwater fracturing fluid.

5. The method of claim 4, wherein the method is used to implement a fracturing method for three-dimensional modification of a tight vertical multi-lithology reservoir. The low-viscosity slickwater fracturing fluid comprises a drag-reducing agent and shale / mudstone inhibitor, and the high-viscosity fracturing fluid comprises a drag-reducing agent and a thickening agent.

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