Nanocomposite plugging agent for drilling shale horizontal wells and preparation method thereof

Abstract

The invention discloses a nano-composite blocking agent for shale horizontal well drilling, and belongs to the technical field of petroleum drilling. The nano-composite blocking agent is prepared fromthe following raw materials in parts by weight: 20 to 30 parts of nano-emulsion, 3 to 8 parts of nanosilicon dioxide, 10 to 20 parts of polyethylene glycol, and 20 to 30 parts of polymeric alcohol, wherein the nano-emulsion is prepared by mixing solid paraffin, white oil, an emulgator and water according to a weight ratio being 2:2:1:5, and stirring for 1h under the conditions of the temperaturebeing 80 DEG C and the stirring speed being 120rpm; a hydrophilic-lipophilic balance value of the emulgator is 10.3. The nano-composite blocking agent has the particle size being smaller than 500nm, is not aggregated or agglomerated, has a certain cloud point and good blocking performance and inhibitive ability, can effectively stabilize a well wall, ensures safe drilling of a shale horizontal well when a water-based drilling fluid is used, has good temperature resistance and stable product performance, and can be applicable to the drilling demand of a long horizontal section of the shale horizontal well.

Description

technical field [0001] The invention belongs to the technical field of petroleum drilling, and in particular relates to a nanocomposite plugging agent for drilling shale horizontal wells and a preparation method thereof. Background technique [0002] Due to the well-developed fractures and strong water sensitivity in shale formations, problems such as collapse and diameter shrinkage are prone to occur when drilling in long horizontal sections, and problems such as friction, rock carryover, and formation pollution are also caused due to the long horizontal section , thus increasing the probability of downhole complex situations. Therefore, in the drilling of shale gas horizontal wells, solving problems such as wellbore stability, drag reduction and friction reduction, and cuttings bed removal have become the key to the selection and design of drilling fluids, and the prerequisite for safe drilling is to maintain wellbore stability. [0003] At present, oil-based drilling flu...

AI Technical Summary

Problems solved by technology

However, these technologies generally have the following deficiencies: the materials and properties of the developed plugging agent are single, the filter cake formed in the drilling fluid is not dense enough, the fluid loss is large, and the plugging ability of micro-nano pores and fractures in shale is not strong. When drilling in long mud shale formations, liquid phase invades mud shale formations, which cannot effectively reduce the risk of mud shale well wall collapse

Chinese patent CN 105985758 A discloses a plugging agent prepared by using emulsified paraffin and soluble mixed salts. The emulsified paraffin is obtained by emulsifying OP series with surfactants such as polyethylene glycol and polyvinyl alcohol, but its active ingredient The particle size of the emulsified paraffin wax is less than or equal to 100 μm, and the formed paraffin wax emulsion has poor dispersion and is easy to aggregate and unite, resulting in fewer nano-sized particles in the final plugging agent, which are basically at the micron level, and the plugging performance is weak , the plugging effect on micro-nano pores and fractures in shale formations is limited

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