Extending method of horizontal well safe density window

Abstract

The invention relates to an extending method of a horizontal well safe density window particularly. The extending method comprises the steps that 1 1.5% of bentonite powder, 1% of saw dust, 1% of blocking agent and 1% of mica powder are added into 100 squares of drilling fluid gradually in a borehole with a standard of 83 / 8''according to a mass-volume percent; 2 the displacement of a drilling pump is lowered when the drilling pump enters a leakage layer; 3 when the leakage layer opens, the rate of penetration is controlled, solid control is strengthened at the same time, and harmful solids in the drilling fluid are removed; 4 the well deviation in an oil shale section is controlled; 5, the orientation of the borehole is conducted with a roller bit. According to the extending method of the horizontal well safe density window, blocking agents of different granularity are added gradually through a mud system, the leak-proofing formula is improved, the concentration of the blocking agent when added into the well is guaranteed to be at 3%, blocking is strengthened, and the strength of a leaking well wall is improved; the displacement of the drilling pump is lowered, the expansion of a crack is prevented, and the collapse pressure of the balance oil shale section is lowered, so that the safe density window is extended.

Description

technical field [0001] The invention belongs to the technical field of petroleum drilling, and in particular relates to a method for extending a safe density window of an oil horizontal well. Background technique [0002] Well Huang 36 area is located in Hongjingzi Township, Yanchi County, Ningxia Autonomous Region - Fengdikeng Township, Dingbian County, Shaanxi Province. It is one of the main blocks for large-scale production of oil horizontal wells in the third oil production plant of Changqing Oilfield in 2013. The development target layer is Chang 8. During the drilling of horizontal wells in the Chang 8 target layer, the Chang 7 oil shale section is long and the well deviation is large and easy to collapse; the Chang 4+5 formation has low pressure bearing capacity, and the drilling fluid density cannot reach the minimum density required to balance the oil shale ;The PDC drill bit is difficult to slide, and the ROP in the deflection section is low. The core of the block...

AI Technical Summary

Problems solved by technology

[0006] 3. The content of lost circulation agent in the drilling fluid is high, the friction caused by fiber particles is large, the sliding viscosity of the PDC drill bit is serious, the under pressure is serious, and the construction efficiency is low

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