A clay-free drilling fluid for protecting low-permeability reservoirs and its preparation method and application

A low-permeability reservoir and drilling fluid technology, applied in the field of drilling fluids, can solve the problems of reduced reservoir permeability, low recovery value of reservoir core permeability, unsatisfactory reservoir protection effect, etc., and achieves good rheological performance, The effect of increasing the recovery value

Active Publication Date: 2019-05-24
CHINA UNIV OF PETROLEUM (EAST CHINA) +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the heterogeneity of the low-permeability reservoir, it is difficult to effectively match various protective materials with the low-permeability reservoir. Filtrate, clay and other solid particles often invade the reservoir, reducing the permeability of the reservoir and resulting in the recovery of the permeability of the reservoir core. Low, the reservoir protection effect is not ideal

Method used

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  • A clay-free drilling fluid for protecting low-permeability reservoirs and its preparation method and application
  • A clay-free drilling fluid for protecting low-permeability reservoirs and its preparation method and application
  • A clay-free drilling fluid for protecting low-permeability reservoirs and its preparation method and application

Examples

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Embodiment

[0042] The present invention will be described in detail through examples below, but the present invention is not limited thereby. In the following preparation examples, examples and comparative examples, unless otherwise specified, the materials used are all commercially available, and the methods used are all conventional methods in the art.

[0043] Hydrophobic associative polyacrylamide, purchased from Chengdu Chunfeng Petroleum Technology Co., Ltd.;

[0044] The structural formula of the waterproof lock agent is C 8 f 17 SO 2 NHCH 2 CH 2 CH 2 Si(OCH 2 CH 3 ) 3 , purchased from Chengdu Chunfeng Petroleum Technology Co., Ltd.;

[0045] Potassium formate, sulfonated bitumen, sulfonated lignite resin and polymer alcohol were provided by China Petroleum Group Drilling Engineering Technology Research Institute.

[0046] The nano-membrane structure reservoir protection agent is prepared according to the following preparation examples 1-4.

[0047] 2-Acrylamido-2-methy...

preparation example 1

[0054] 1. Preparation of organic montmorillonite

[0055] Put 5g of sodium montmorillonite, 3g of cetyltrimethylammonium chloride and 100ml of distilled water in a 250ml flask, stir at 120rpm in a water bath at 80°C for 4h, let stand overnight, remove the upper solution, filter, and wash with deionized water to no Cl - (with a concentration of 0.01mol / L AgNO 3 solution test), dried in a vacuum oven at 70°C, and crushed through a 300-mesh sieve to obtain organic montmorillonite (O-MMT).

[0056] 2. Preparation of nano-membrane structure plugging agent

[0057] (1) In a three-necked flask equipped with a thermometer and a mechanical stirrer, add styrene, benzyl dithiobenzoate and azobisisobutyronitrile at a molar ratio of 400:1:0.4, and add styrene 5% by weight of organic montmorillonite, after sealing the reaction device, the air in the system was removed by freezing and vacuuming, filled with nitrogen, and circulated for 3 times, fully stirred under the protection of nitrog...

preparation example 2

[0060] Prepare organic montmorillonite according to the method of preparation example 1, and the preparation method of nano-membrane structure sealing agent is as follows:

[0061] (1) In a three-necked flask equipped with a thermometer and a mechanical stirrer, add p-methylstyrene, cumyl dithiobenzoate and azobisisoheptanonitrile at a molar ratio of 200:1:0.3, And add organic montmorillonite accounting for 3% by weight of p-methylstyrene, seal the reaction device, remove the air in the system by freezing and evacuating, fill with nitrogen, cycle 3 times, fully stir under the protection of nitrogen, and heat at 130 ° C The reaction was carried out in an oil bath. After reacting for 2.5 hours, the reaction system was cooled with an ice-water bath, and the product was precipitated in methanol, filtered, and then dried in vacuum at 70° C. to obtain poly-p-methylstyrene / montmorillonite nanocomposite macromolecular chain transfer agent.

[0062] (2) In the there-necked flask equip...

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Abstract

The invention relates to the field of drilling fluid during a petroleum and natural gas exploration and development process, and discloses clay-free drilling fluid for protecting a low-permeability reservoir as well as a preparation method and application thereof. The clay-free drilling fluid is prepared from hydrophobic associative polyacrylamide, a nano membrane-structure reservoir protective agent, a water blocking preventive, potassium formate, sulfonated bitumen, sulfonated walchowite, polymeric alcohol and water, wherein the water blocking preventive is N-perfluoroalkyl sulfonyl propyl triethoxysilane; the hydrophobic associative polyacrylamide comprises a structural unit as shown in a formula (1) which is shown in the description and a structural unit as shown in a formula (2) whichis shown in the description; the nano membrane-structure reservoir protective comprises a montmorillonoid sheet layer, a structural unit as shown in a formula (3) which is shown in the description and a structural unit as shown in a formula (4) which is shown in the description. According to the clay-free drilling fluid disclosed by the invention, a reservoir protection effect of a system is obvious because of no addition of proportioning bentonite particles, and the return permeability is greater than 95 percent. The formulas are shown in the description.

Description

technical field [0001] The invention relates to the field of drilling fluids in the exploration and development of oil and natural gas, in particular to a clay-free drilling fluid for protecting low-permeability reservoirs and its preparation method and application. Background technique [0002] Drilling fluid is one of the important measures to ensure safe, efficient, high-quality and fast drilling operations. Drilling fluid must be used in oilfield operations. [0003] Effective reservoir protection is an important guarantee for improving oil and gas recovery in low-permeability reservoirs, so that the skin coefficient is negative to achieve the best. During the drilling process, if the performance of the drilling fluid is poor, the filtrate, clay and other solid particles in the drilling fluid will invade the reservoir, and have physical and chemical interactions with the clay and other minerals in the reservoir or physically block the pore throat, reducing the wellbore ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/12
CPCC09K8/12
Inventor 刘敬平孙金声吕开河黄贤斌
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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