Multi-component vinyl polymer emulsion film-forming plugging agent for drilling fluid and preparation method thereof

Abstract

The invention provides a preparation method of a multielement vinyl polymer emulsion film forming blocking agent for a drilling fluid. The preparation method comprises the steps as follows: raw materials are prepared according to the component ratio; a solvent accounting for 4 / 5 of the formula quantity and an emulsifier are added to a No. 1 reactor in sequence, heated to 50-70 DEG C and stirred for 20-30min; then, styrene, maleic anhydride, acrylate, an initiator and a molecular weight regulator are added in sequence, the mixture is heated to 70-80 DEG C, timing for a reaction is started, and the mixture is stopped from being heated after 1 h and cooled; the solvent accounting for 1 / 5 of the formula quantity, a stabilizer, a deoxidant, a defoamer and modified nano-calcium carbonate are added to a No. 2 reactor in sequence and are stirred at the room temperature for 30-40 min; the mixture obtained in the previous step is added to the No. 1 reactor slowly and reacts at 40-50 DEG C for 2-3 h, and the multielement vinyl polymer emulsion film forming blocking agent is obtained. In combination with micro-scale deformable and cementing film forming particles, the blocking and collapse preventing capacity of the drilling fluid is improved, the mud cake quality is improved, the filter loss is reduced, the compatibility is good, and the temperature of 130 DEG C can be resisted.

Description

technical field [0001] The invention relates to the field of oil and gas well exploitation, in particular to a multi-element vinyl polymer emulsion film-forming plugging agent for drilling fluid and a preparation method thereof. Background technique [0002] Borehole wall instability is one of the problems often encountered by field engineers around the world. This problem is particularly prominent in shale well sections. 90% of the world's well wall stability problems occur in shale formations. The problem of well wall instability greatly prolongs the drilling construction period, and also causes very huge losses to the exploration and development work. In the past, to solve the plugging problem of shale well sections, mud cake plugging technology was often used to prevent well wall collapse. However, for tight hard and brittle shale formations, the content of illite is high and the content of montmorillonite is low. In fact, pressure transmission and The strength reductio...

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Problems solved by technology

The problem of well wall instability greatly prolongs the drilling construction period, and also causes very huge losses to exploration and development work

In the past, to solve the plugging problem of shale well sections, mud cake plugging technology was often used to prevent well wall collapse. However, for tight hard and brittle shale formations, the content of illite is high and the content of montmorillonite is low. In fact, pressure transmission and The strength reduction caused by crack propagation is the main cause of damage. The actual effect of preventing collapse by increasing the salinity to increase the inhibition of hydration is not great. The reason is that the water inlet channel expands under the condition of multi-field coupling, so it must be effectively cut off. Blocking technology to prevent collapse

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