Analysis of the current issue of well bore and well bottom cleaning

Abstract

The paper considers the problem of insufficient cleaning of oil and gas wells from drill cuttings. The formation of slurry dunes is the main cause of complications and accidents in horizontal well drilling. The task related to the development of high-efficiency equipment for well bottomhole cleaning from drill cuttings is quite relevant. The existing techniques and technologies for borehole bottom cleaning from drill cuttings caused by rotary drilling were analyzed to find a way of improving the efficiency of borehole bottom cleaning. A new technical solution for cleaning vertical, directional and horizontal wells from drill cuttings was developed. The process functional diagram of at-bit sludge chopper during turbine drilling is presented to increase the cleaning efficiency of bottomhole and wellbore of vertical, directional and horizontal wells from drill cuttings during roller boring.

Investigating formation resistance to fracture during operation of wells prone to plugging

“…The largest difference in normal stresses occurs on the borehole wall since the radial stresses are equal to the minimum values, and the tangential stresses are equal to the maximum values [1]. Therefore, depending on the formation pressure drawdown and the strength properties of the fixed zone, the following well operating conditions are possible:  The fixed near-wellbore part of the formation is in an elastic state throughout the entire volume, that is, the following condition is fulfilled:…”

“…The fixed near-wellbore part of the formation is in a plastic state throughout the entire volume, that is, the following condition is fulfilled: (2) Where is yield point. It is known from the solution of the elastic problem that the largest difference between the normal stresses in the body of a hollow sphere during fluid filtration through its wall to the center takes place on the inner surface ( ) [2]. Therefore, the conditions for the fluidity of the ball material will arise, first of all, on the inner surface of the ball, which can be written as follows:…”