China University of Petroleum

Qingdao University of Technology

Guizhou Engineering Research Institute of Oil & Gas Exploration and Development

Chang Lu

Huajie Liu

Yuhuan Bu

Shenglai Guo

Xinyang Guo

Qiang Wang

Rui Ma

Changyou Xiang

Shengda Shen

Dong Lin

Doudou Wang

Xun Shan

Yuanlong Wei

Qi Zhao

Heng Yang

Lingyun Zhao

Meihua Huo

Shaorui Jing

A sealing gel with delayed gelation for well cementation, its preparation method, and application are provided. The sealing gel with delayed gelation for well cementation includes 2-3 parts of anionic polyacrylamide, 3-4 parts of cationic acrylamide, 1 part of stabilizer, 1 part of cross-linking agent and 6 parts of distilled water; the stabilizer is obtained by the reaction of citric acid and ethylenediaminetetraacetic acid disodium under the action of initiator, the cross-linking agent is obtained by the reaction of chromium lactate and chromium nicotinate under the action of azo diisobutyl amidine hydrochloride and tetramethylethylenediamine. Based on the purpose of well cementation, the sealing gel has pH sensitivity, which prolongs the gelation time of the gel that is originally rapidly formed at a certain temperature, so that it can be added to the pre-liquid system.

Sealing gel with delayed gelation for well cementation, preparation method, and application

Anti-corrosion and low-heat-conduction annulus protection fluid for deep-sea oil and gas exploitation and a preparation method thereof are provided. The annulus protection fluid includes: a polymer solution: 100 parts, clear water III: 100 parts to 500 parts, a thermally-insulating material: 20 parts, a corrosion inhibitor: 1 part to 7 parts, and xanthan gum: 0.3 parts to 0.5 parts, wherein the polymer solution is a mixture of a polymer and clear water II in a mass ratio of 1:(22-28); and the polymer includes the following raw materials: clear water I: 100 parts, an acrylamide: 15 parts to 20 parts, 2-2-methylpropanesulfonic acid: 5 parts to 10 parts, a crosslinking agent: 0.1 parts to 0.3 parts, and an initiator: 0.5 parts to 1 part. The annulus protection fluid exhibits excellent thermal insulation performance and corrosion resistance, and avoids the generation of hydrates and the decomposition of hydrate layers at a wellhead.

Anti-corrosion and low-heat-conduction annulus protection fluid for deep-sea oil and gas exploitation and preparation method thereof

An intra-layer reinforcement method, and a consolidation and reconstruction simulation experiment system and an evaluation method for a gas hydrate formation are provided. In the intra-layer reinforcement method, the formation reconstruction and fracturing grouting reinforcement technologies are combined; a fracturing grouting process is adopted to create fractures in the gas hydrate formation; and a consolidation liquid enters the fractures and penetrates into the formation through a pressure difference to form a reinforcement with a ribbed slab structure and a specified strength and permeability, which supports the formation to achieve collapse prevention and sand prevention. A specific consolidation and reconstruction simulation experiment system is adopted, where the necessary conditions for the generation and decomposition of a hydrate are tested, and the fracturing, formation consolidation, and cementing experiments are simulated to study a rational exploitation method of a gas hydrate, thereby solving the problem of sand production of the hydrate layer.

Intra-layer reinforcement method, and consolidation and reconstruction simulation experiment system and evaluation method for gas hydrate formation

An oil well cement composite permeation enhancement agent suitable for a hydrate layer and a preparation method thereof are disclosed. In parts by weight, the composition of raw materials of the composite permeation enhancement agent is 4.6 parts-5.0 parts of kerosene, 0.23 parts-0.25 parts of emulsifier, 0.8 parts-1.1 parts of modified polypropylene fiber, 10.0 parts-12.0 parts of porous and permeable microspheres, 1.0 part-1.2 parts of paraffin, and 57.5 parts-62.5 parts of water. The composite permeation enhancement agent can effectively improve the permeability of the cement stone which reshapes the formation framework and increase the mining rate of hydrate. The oil well cement composite permeation enhancement agent has the advantages of long-term performance, low cost, and green environmental protection. The composite permeation enhancement agent of the present invention does not need secondary treatment to increase permeation, the operation is convenient and fast, and the working time of holding pressure is reduced.

Oil well cement composite permeation enhancement agent suitable for hydrate layer and preparation method

A scour-resistant interface enhancer, a preparation method, and an application thereof are provided. The scour-resistant interface enhancer is a compound solution prepared by using a 0.1% surfactant CAEO-15 and a 0.3% silane coupling agent as solutes and using clear water and absolute ethanol as solvents, where the mass ratio of clear water to absolute ethanol is 9:1. The scour-resistant interface enhancer of the present invention used as pre-flush for well cementing of coalbed methane wells has good wettability modification effect, shows scour-resistant effect against cement slurry, exhibits good compatibility with cement slurry system, and can significantly improve the cementing strength and air tightness of two interfaces of coal bed and effectively enhance the cementing quality of coalbed methane wells.

Scour-resistant interface enhancer used for well cementing of coalbed methane wells, preparation method, and application

A performance evaluation device and a design method of a cement for well cementing in a penetrated hydrate layer are provided. The performance evaluation device includes an equivalent wellbore, an inner circulation system, an outer circulation system, a thermal insulation cover, a bracket, a temperature sensing system, and a cement mold. The device can simulate a true downhole situation, conduct an evaluation experiment on the heat insulation performance of a cementing cement, and conduct experiments at different temperatures with automatic temperature control. The design method is to use a low-hydration, early-strength, and heat-insulating cement slurry system during the well cementing in a penetrated hydrate layer, where the low-hydration and early-strength characteristics ensure the effective sealing of a hydrate layer during a cementing process, and the heat insulation characteristic results in low heat conductivity and thus can ensure the stability of a hydrate layer during a production operation.

Method of cement for well cementing in penetrated hydrate layer

Cement performance evaluation device and cement design method for cementing in penetrated hydrate deposit

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Qingdao, China

Chang Lu