Micron-nano plugging anti-sloughing drilling fluid, and preparation method and application thereof

Abstract

The invention relates to the field of drilling fluid and discloses a micron-nano plugging anti-sloughing drilling fluid, and a preparation method and an application thereof. The drilling fluid contains water, bentonite, a fluid loss agent, an anti-sloughing agent, a nano-plugging agent, and a weighting agent, wherein the anti-sloughing agent is selected from one or more of modified asphalt, CaCO3powder and nano paraffin emulsion, the CaCO3 powder being 400-mesh and 1250-mesh. The D50 (particle size mid-value) of the nano paraffin emulsion is 6.5 [mu]m; the nano-plugging agent is surface-modified nano-carbon powder, average particle size being 30-85 nm. The drilling fluid, when being applied to carbonatite fractured formation well drilling of fracture zones in deep and super-deep wells, can effectively improve the collapse pressure of the fractured formation and is high-effective in plugging and anti-sloughing effect.

Description

technical field [0001] The invention relates to the field of drilling fluids, in particular to a micro-nano plugging and anti-collapse drilling fluid and a preparation method and application thereof. Background technique [0002] In the process of drilling fractured carbonate formations in deep and ultra-deep well fault zones, the non-equilibrium in-situ stress of formations is broken, often resulting in stress-releasing fractures. Drilling fluid filtrate intrusion into formation pores and fractures will destroy the effective cementation between formation rock clay minerals, resulting in further expansion and connection of micro-nano pores and fractures, resulting in a decrease in borehole wall collapse pressure. During the process of drilling or lifting and lowering, the rotating drilling tool will inevitably have a mechanical impact on the well wall, causing the well wall to collapse and fall off. Drilling costs. [0003] Although the use of oil-mixed drilling fluid or o...

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Problems solved by technology

[0007] The purpose of the present invention is to overcome the defects of high cost and non-environmental protection of using oil-based drilling fluid. The plugging and anti-collapse effect of conventional water-based drilling fluid is not ideal when drilling in fractured carbonate formations in deep wells and ultra-deep wells. As well as the disadvantages of poor dispersion stability of conventional nano-blocking agents in high-temperature and high-pressure environments, and the defects of easy agglomeration in drilling fluids, a micro-nano plugging and anti-slumping drilling fluid and its preparation method and application, the drilling fluid can effectively block and prevent collapse when drilling in fractured carbonate formations in deep and ultra-deep well fault zones

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