Influence of well walls filtration cake on their stability
UDC: 622.276.1/.4:622.24
DOI: 10.33285/2413-5011-2023-11(383)-40-45
Authors:
SVALOV ALEXANDER M.
1
1 Oil and Gas Research Institute of Russian Academy of Sciences, Moscow, Russia
Keywords: rock destruction, filter cake, well walls stability, horizontal wells
Annotation:
The author of the article analyzes the patterns of loss of wells walls stability during drilling. It is shown that the effectiveness of drilling fluid counter-pressure on the well walls, which prevents the rock destruction in the near wellbore zones, is different when drilling permeable and impermeable rocks. It has been revealed that in permeable rocks, including productive formations, filtration processes reduce the effectiveness of such back pressure, but the formation of a low-permeable filter cake on the walls of a well, being drilled, significantly increases their resistance to destruction.
An analysis of stress concentration processes in the near-wellbore zones of horizontal wells showed that at the depths of about 2 km or more, rock destruction almost inevitably occurs in these zones, but the presence of a filter cake on the well walls prevents an increase of pore pressure in the destroyed rock and contributes to its compression, as a result of which there is no falling out of the destroyed rock into the wellbore of the well, being drilled.
It is shown that when drilling low permeable rocks, the effectiveness of the filter cake influence on the stress-strain state of the rock will decrease, which will make the problem of well walls stability of the wells being drilled, more acute.
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