Gas plug slurry for underbalanced drilling

Abstract

The invention discloses under-balanced drilling qi-stagnation slurry which is prepared by the following steps: 1) weighing the following components by volume percent: 0.5-0.7% of tackifier, 0.3-0.5% of flow pattern modifier, 0.5-1.5% of tackify filtrate reducer, 7-9% of bentonite, 0.1-0.3% of sodium carbonate and the balance of water; 2) putting water into a circulating tank, and then orderly adding the sodium carbonate, the bentonite, the tackifier, the flow pattern modifier and the tackify filtrate reducer to the circulating tank by virtue of a mixing funnel, so that the components are fully hydrated and evenly dissolved; 3) shearing for 10-30 minutes by use of a mud gun of the circulating tank under mechanical agitation, thereby preparing the under-balanced drilling qi-stagnation slurry. The qi-stagnation slurry has good heat resistance, glutinousness and thixotropy, and a gas cannot flow upwards in the well, and just can move upwards in a manner of integrally supporting a liquid post. Thus, the condition that the shaft bottom is in an under-balanced state in the drilling process is ensured.

Description

technical field [0001] The invention relates to the technical field of petroleum underbalanced drilling, in particular to a gas-slugging slurry for underbalanced drilling. Background technique [0002] The pressure coefficient of the buried hill in Huabei Oilfield is less than 1, so permeability loss, micro-fracture loss and fracture loss are prone to occur; the formation is complex, the wellbore structure is complex, and the construction is difficult. Drilling low-pressure reservoirs in buried hills with conventional drilling fluid with higher density will cause partial or complete loss of drilling fluid. Underbalanced drilling techniques are generally required to develop these reservoirs in order to avoid increased drilling costs, formation fractures, formation damage and well retirement. [0003] When underbalanced drilling technology is used to uncover buried hill oil and gas reservoirs, risks such as gas channeling and well kicks will occur during the tripping process,...

AI Technical Summary

Problems solved by technology

At present, the existing method mainly adopts the replacement of high-density drilling hydraulic wells. The disadvantage is that it consumes a large amount of drilling fluid weighting materials, and at the same time, it cannot completely prevent the gas from going up, which will cause hidden dangers to the tripping work.

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