Anti-collapse and leakproof drilling fluid and construction method thereof

Abstract

The invention relates to the technical field of petroleum drilling, and particularly relates to anti-collapse and leakproof drilling fluid and a construction method thereof, which are applicable to a Mesozoic Triassic stratum having the characteristics of low loading capacity, repeated block leakage and large leaking stoppage difficulty. The drilling fluid is composed of polyanionic cellulose, a drilling fluid salt-resistant filtrate-loss reducer, water dispersible emulsified asphalt powder, ultrafine calcium carbonate, sodium formate, sodium hydroxide, potassium chloride and water. Due to the application of a salt-poor low soil phase, the sealing capacity of a mud cake is improved and the loading capacity of the stratum is enhanced; low density is effectively controlled, and the probability of induced lost circulation is reduced; and the pump delivery is reduced, and the erosion of the drilling fluid to the wall of a well is reduced, thereby protecting the wall of the well from collapsing. According to the invention, through enhancing the loading capacity of the stratum, the low density is effectively controlled, the pump delivery is reduced, the probability of lost circulation is reduced, the drilling cycle of the block is greatly reduced, and the drilling cycle is shortened by over 50%.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling, in particular to an anti-slump and anti-leakage drilling fluid and a construction method thereof, which are suitable for Mesozoic Triassic strata with low pressure bearing capacity, repeated block leakage and great difficulty in plugging. Background technique [0002] The Sulige block is mainly distributed in the Ordos Basin of the Inner Mongolia Autonomous Region. The geological structure of this block belongs to the Yishan slope, in which the Yanchang Formation and Liujiagou Formation belong to the Mesozoic Triassic strata, and the lithology of the Yanchang Formation is mainly gray-green, dark Mudstone and gray sandstone are interbedded, and the burial depth is about 1500-2300 meters. The lithology of the Liujiagou Formation is mainly gray-purple and gray-white massive sandstone, and the burial depth is about 2500-2950 meters. The upper part of the Shihezi Formation is a set of conti...

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Problems solved by technology

[0005] 1. Lost circulation occurred in the Yanchangdi, Liujiagou and Shihezi formations in the Sulige block, especially the Liujiagou formation has low pressure bearing capacity and low solid phase content in the drilling fluid. Effective plugging of leaky layer channels, difficult plugging, long plugging well section, low plugging success rate

[0006] 2. If the density is not increased in the highly deviated well section, effective liquid column pressure cannot be used to support the well wall. After drilling in the deviated well section, due to the low displacement, it cannot effectively carry sand, and it is easy to cause drilling sticking

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