Anti-collapse drilling fluid for coal bed methane horizontal well and method for preparing anti-collapse drilling fluid

Abstract

The invention provides anti-collapse drilling fluid for coal bed methane horizontal well. The drilling fluid is used for preventing the collapse of the wall of the well in the well drilling process. The drilling fluid is characterized by comprising the following components in percentage by weight: 0.1 to 0.3 percent of potassium polyacrylate, 0.1 to 0.5 percent of sodium lignosulfonates, 0.1 to 0.3 percent of GHA-5 type coal water slurry additive, 0.5 to 3 percent of potassium chloride, 0.4 to 0.6 percent of potassium humate, 0.3 to 0.5 percent of sulfonated lignite, 1 to 3 percent of graphite powder and the balance of water. The sum of weight percent of the components is 100 percent. The drilling fluid has the advantages of effectively preventing the expansion of the coal matrix, inhibiting the collapse of the wall of the well due to the immersion of the coal bed in clean water, dissolving macromolecules adsorbed in the coal bed, lowering the surface tension of the coal matrix on the premises of keeping the normal physical characteristics unchanged, facilitating the flowback of the drilling fluid and lowering the pollution of the coal bed; the drilling fluid is prevented from being absorbed on the surface of coal, so that a gas channel cannot be blocked; and by adjusting the proportion of additives, the well-drilling construction is guaranteed.

Description

technical field [0001] The invention relates to the technical field of coalbed methane horizontal well drilling, in particular to a drilling fluid used for suppressing borehole wall collapse during the drilling process of coalbed methane horizontal wells. Background technique [0002] In order to prevent the well wall from collapsing during the drilling of coalbed methane horizontal wells, it is generally used to add proppant to the drilling fluid to enhance the stability of the well wall. The commonly used proppants include various polymers and other patented products. This method can effectively enhance the stability of the borehole wall, avoid accidents such as drill sticking and buried drill during the drilling process, and ensure the smooth progress of drilling construction. During the actual application, it was found that although the proppant can stabilize the well wall, due to the unique adsorption and low permeability of the coal seam, the drilling fluid is adsorbed...

AI Technical Summary

Problems solved by technology

After the formula ingredients in this patent enter the coal seam, it fills its cleat system and is difficult to degrade, and it is easy to block the water and gas production channels of the coal seam. It is not suitable for the drilling of coalbed methane horizontal wells