Repeated transformation method for improving crack plugging effect

A technology for repeated reconstruction and artificial fractures, applied in chemical instruments and methods, earthwork drilling, drilling compositions, etc., can solve problems such as failure to seal natural or artificial fractures, low bearing strength, and affecting oil well productivity

Active Publication Date: 2021-02-23
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the ultra-low permeability reservoirs in this basin have entered the middle water-cut stage of development. Due to the influence of natural fractures and artificial fractures, the number of fractured water-flooded wells has increased year by year, which has seriously affected the productivity of oil wells.
In order to control the water-flooded wells with fractures, a water plugging fracturing test of "plugging old fractures and pressing new fractures" was carried out. The technical idea is to use the gel system to plug the deep part of the fracture, and use the cement-type high-strength plugging agent to plug the near fracture. In the well area, re-hole fracturing is performed again. The limitation of this technology is that the gel system has a low pressure bearing strength, and the fractures generated by pore-repair fracturing are easy to communicate with the initial artificial fractures, while the plugging range of high-strength cement plugging agents is limited In the well area, it is impossible to seal the natural or artificial cracks in the direction of water flow, and because of the need to replace and inject high-strength cement plugging agent, there is a cement plug left in the casing, which needs to be drilled to open the cement plug, which is costly and has a long construction period. In order to avoid cement-based plugging agent returning to high solidification and sticking, the pipe string structure must be designed as "oblique tip + tubing", so that it is limited to the treatment of water breakthrough wells in a single oil layer

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] This embodiment provides a repeated reconstruction method for improving the crack plugging effect, which includes the following steps:

[0040] Step 1) Prepare 10m 3 Differential pressure activates sealant A, 20m 3 The differential pressure activates sealant B;

[0041] Step 2) at 0.5-2.0m 3 / min inject 10m 3 Active water, low replacement and setting;

[0042] Step 3) at 2.0m 3 / min Inject 10m into the target layer 3 Cross-linking liquid carrying 2.0m 3 40-70 mesh quartz sand;

[0043] Step 4) at 2.0m 3 / min Inject 10m into the target layer 3 Differential pressure activates sealant A;

[0044] Step 5) at 2.0m 3 / min inject 20m 3 Differential pressure activates sealant B;

[0045] Step 6) at 2.0m 3 / min Inject guar base fluid to activate the sealant replacement into the formation by the pressure difference in the wellbore, and stop the pump for 1 hour;

[0046] Step 7) at 3.0m 3 / min Displacement, 300m 3 The amount of liquid entering the ground and 30m 3 ...

Embodiment 2

[0051] In order to make up for the shortcomings of conventional water plugging fracturing, this example provides this repeated reconstruction method to improve the effect of fracture plugging, including the following steps:

[0052] Step 1) Prepare 20m 3 Differential pressure activates sealant A, 30m 3 The differential pressure activates sealant B;

[0053] Step 2) at 0.5-2.0m 3 / min inject 15m 3 Active water, low replacement and setting;

[0054] Step 3) at 3.0m 3 / min Inject 15m into the target layer 3 The cross-linking solution carries 2.5m 3 40-70 mesh quartz sand;

[0055] Step 4) at 3.0m 3 / min Inject 20m into the target layer 3 Differential pressure activates sealant A;

[0056] Step 5) at 3.0m 3 / min injection 30m 3 Differential pressure activates sealant B;

[0057] Step 6) at 3.0m 3 / min Inject guar base fluid to activate the sealant replacement into the formation by the pressure difference in the wellbore, and stop the pump for 2 hours;

[0058] Step ...

Embodiment 3

[0061] A repeated reconstruction method for improving the sealing effect of cracks, comprising the following steps:

[0062] Step 1) Prepare 8m 3 Differential pressure activated sealant A, 22m 3 The differential pressure activates sealant B;

[0063] Step 2) at 0.5-2.0m 3 / min inject 10m 3 Active water, low replacement and setting;

[0064] Step 3) at 3.0m 3 / min Inject 20m into the target layer 3 Cross-linking liquid carrying 4.0m 3 40-70 mesh quartz sand;

[0065] Step 4) at 3.0m 3 / min Inject 8m into the target layer 3 Differential pressure activates sealant A;

[0066] Step 5) at 3.0m 3 / min inject 22m 3 Differential pressure activates sealant B;

[0067] Step 6) at 3.0m 3 / min Inject guar base fluid to activate the sealant replacement into the formation by the pressure difference in the wellbore, and stop the pump for 1 hour;

[0068] Step 7) at 3.0m 3 / min Displacement, 350m 3 The amount of liquid entering the ground and 35m 3 The construction parameter...

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Abstract

The invention discloses a repeated transformation method for improving the crack plugging effect. A differential pressure chemical plugging technology and a repeated fracturing technology are combined, a differential pressure activating sealant A is injected into a target layer, the sealant filters out pores of a reservoir matrix through primary fracturing artificial cracks of the target layer, acertain throttling pressure difference can be formed, under the action of the pressure difference, the differential pressure activating sealant A is polymerized to form a high-temperature-resistant and high-pressure-resistant tough solid, and thus reservoir pores are plugged; a differential pressure activating sealant B is injected into the target layer, a certain throttling pressure difference can be formed when the sealant passes through a pore passage between the artificial cracks and a propping agent, polymerizing can be conducted under the action of the pressure difference to form a high-temperature-resistant and high-pressure-resistant tough solid, and thus the artificial cracks and a large pore passage are plugged; and repeated fracturing is conducted on the target layer, under theplugging effect of the differential pressure activating sealants, the cracks are inhibited from extending along the primary artificial cracks, the net pressure is increased, new cracks are forced to be opened, the original artificial cracks with water are avoided, and remaining oil is used.

Description

technical field [0001] The invention belongs to the technical field of downhole operations in oil field exploration and development, and in particular relates to a repeated transformation method for improving the plugging effect of fractures. Background technique [0002] The ultra-low permeability reservoirs in the Ordos Basin have relatively well-developed natural fractures and low reservoir energy. Water flooding is used for development, and water flooding has obvious directionality. The injected water advances rapidly along the direction of natural fracture development, thereby flooding the oil well. Most of the ultra-low permeability reservoirs in this basin have entered the middle water-cut stage of development. Due to the influence of natural fractures and artificial fractures, the number of fractured water-flooded wells has increased year by year, which has seriously affected the productivity of oil wells. In order to control the water-flooded wells with fractures, a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/26E21B43/267C09K8/50
CPCE21B43/26E21B43/261E21B43/267C09K8/50Y02E10/10
Inventor 王飞姚建国李向平吕宝强达引朋卜军汪澜杨军侠
Owner PETROCHINA CO LTD
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