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Water-based drilling fluid for leakage protection and sealing of induced fissures

A water-based drilling fluid and inductive technology, applied in the field of drilling fluid, can solve the problems of leakage economic loss, the success rate of one-time plugging is less than 80%, and the distribution area of ​​induced fractures is wide, so as to achieve the effect of improving the success rate

Active Publication Date: 2015-12-30
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the induced fractures are often distributed in a wide area, and it is difficult to accurately grasp the size of the fractures, and the plugging effect is even less ideal.
[0003] Taking Huaqing Oilfield as an example, since 2008, the problem of well leakage has become more and more prominent. The number of wells with leakage, leakage volume, leakage time, and leakage loss have increased. Most of Huaqing Oilfield is sandstone and the permeability of Luohe Yijun formation. Leakage, the one-time plugging success rate is less than 80%, and the annual economic loss of leakage exceeds several million yuan
During the construction of block Yuan 284, there were more than ten serious well leakages, the success rate of plugging was less than 50%, and the loss was tens of millions of yuan
[0004] Since the induced fractures are often distributed in a wide area, it is difficult to accurately grasp the size of the fractures, while the plugging range of conventional bridging and plugging agents is narrow, so the plugging effect on induced fractures is even less ideal

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] This embodiment provides a water-based drilling fluid for leak prevention and plugging of induced fractures, which includes the following substances in weight percentage:

[0044] A. Polyacrylamide: 0.3% to 0.5%.

[0045] B. Sulfonated pitch: 0.5% to 0.6%.

[0046] C. Fluid loss reducer: 0.3% to 0.5%.

[0047] D. Polymer gel plugging agent: 0.2% to 0.3%,

[0048] The polymer gel plugging agent is an inorganic salt that can provide potassium ions or sodium ions, where the polymer gel plugging agent can be potassium chloride or sodium chloride or potassium nitrate.

[0049] E. Bridge plugging agent: 0.3% to 0.5%,

[0050] The particle size distribution of bridge plugging agent is:

[0051] 15-20% particle size 0.05-0.1mm;

[0052] 20-25% particle size 0.1-0.2mm;

[0053] 15~20% particle size 0.2~0.3mm;

[0054] 5~15% particle size 0.3~0.4mm;

[0055] 5~10%QD-2;

[0056] 1~5% particle size 0.4~0.5mm.

[0057] F. Rubber particles: 2% to 3%,

[0058] The particle ...

Embodiment 2

[0095] Qingtongxia sodium soil 12%+NaOH0.6%+Na2CO30.4%+QD—22%+QD—36%+3mm rubber particles 3%+5mm rubber particles 4%+8mm rubber particles 3%+CDL—10.5% +2-4 mesh rice stone 6%+5-8 mesh rice stone 3%+5-20 mesh rice stone 5%.

[0096] Field application of leak plugging in Well Yuan 303-54: the leaked well is 600-770m deep, the leaked layer is multi-point leaked in the Luohe Formation, and the leaked rate is 40-60m 3 / h, the leakage volume is 450m 3 .

[0097] At 23:00 on July 12th, when drilling to 600 meters, there was a sudden serious loss of no return. Up and down movable drilling tools, equipped with bridge plug plugging slurry 40m 3 After injecting into the bottom of the well, turn on the pump for 50 seconds, 1 / 2 of the mud will return, and resume drilling after the circulation is normal. At 12:00 on July 13th, the fluid volume gradually decreased at a depth of 670-700 meters, and the leakage increased. When the drilling reached 727 meters, the mud did not return to the ...

Embodiment 3

[0100] Qingtongxia sodium soil 10%+NaOH0.5%+Na2CO30.3%+QD—23%+QD—35%+5mm rubber particles 2%+8mm rubber particles 1%+CDL—10.5%+2—4 mesh rice Stone 5% + 5-20 mesh rice stone 4%.

[0101] Field application of leak plugging in well Yuan 307-55:

[0102] The leaking well is 572-1020m deep, and the leaking layer is multi-point leaking in the Luohe Formation, and the leaking rate is 30-50m 3 / h, the leakage volume is 600m 3 . There was liquid flow back in the well, and the construction team did not pay enough attention to it, so the leakage was plugged by the method of plugging while drilling.

[0103] At 21:00 on August 5th, clear water was used for two openings, and at 11:20 on August 7th, when drilling reached 572 meters, a serious leakage occurred suddenly. Drilling out to the casing corner, equipped with bridge plug plugging slurry 20m 3 After injecting into the bottom of the well, inject 10m at the wellhead for 12 minutes 3 Drilling fluid was not poured to the wellhead; ...

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Abstract

The invention relates to water-based drilling fluid for leakage protection and sealing of induced fissures. The water-based drilling fluid is prepared from polyacrylamide, sulfonated bitumen, a filtrate reducer, a polymer gel lost circulation agent, a bridge plug lost circulation agent, rubber particles, a one-way pressure blocking agent, saw dust, mica, vermiculite, an alkalinity control agent and water. By means of the water-based drilling fluid for leakage protection and sealing of the induced fissures aims, according to the practical problems that the induced fissures change and a conventional bridging lost circulation agent is small in blocking range, an elastic lost circulation material, a complex micelle polymer and a packing material leakage protection and sealing agent are studied and selected and can generate an effective blocking effect on wide-dimension fissures, the dependency on the dimension of a leakage channel by a traditional bridging lost circulation agent is overcome to a certain degree, the success rate to the leakage protection and sealing of the induced fissures is increased, the loading capacity reaches 4 mPa, a leaking layer can be effectively blocked within short time, and the leakage protection and sealing effect is achieved.

Description

technical field [0001] The invention belongs to the field of drilling fluids, in particular to a water-based drilling fluid for leak prevention and plugging of induced fractures. Background technique [0002] Lost circulation is one of the most serious hazards that affect the safety of drilling operations. The occurrence of lost circulation will not only bring losses to drilling engineering, but also bring great difficulties to the exploration and development of oil and gas resources. The lost circulation problem has always been a major engineering technical problem that plagues oil exploration and development at home and abroad, and it has not been completely resolved so far. The most widely used bridging and plugging agents at present must accurately grasp the size of formation pores or fractures. However, the induced fractures are often distributed in a wide area, and it is difficult to accurately grasp the size of the fractures, and the plugging effect is even less ideal...

Claims

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Application Information

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IPC IPC(8): C09K8/12C09K8/24C09K8/487
CPCC09K8/12C09K8/24C09K8/487C09K2208/18
Inventor 赵巍吴学升李波高云文王勇茗
Owner PETROCHINA CO LTD