Research Of Reservoir Protection Adaptiveness In Lishu Fault

Lishu fault depression in southern Songliao basin is the main oil and gas accumulation zone, reservoiris low porosity and low permeability of tight clastic rock reservoir. Lishu in wellbore stability and reservoirprotection drilling difficulties technology great difficulty in drilling process. Mainly because of long openhole section, drilling through the formation of multiple and complex, with mud soak time prolonged, theeasy peeling, leading to wellbore instability, thereby causing downhole complicated conditions; and withthe exploration and development of deep well and deep well, gradually increased, the same well pressuresystem is not a, dense and strong heterogeneity reservoir. Therefore, reservoir protection technology ofLishu fault is of great significance.In order to enhance wellbore stability and reservoir protection effects, carried out research work of lowdamage strong inhibition drilling fluid. This paper mainly analyses the reason of borehole instability, thesidewall instability is due to the formation of expansive clay mineral content is high, drilling fluidinhibition caused by insufficient; secondly, studied the mechanism of reservoir damage, includingsensitivity evaluation, solid-liquid phase damage evaluation, the reservoir damage to solid invasion andliquid pollution. Borehole instability; according to the reason and the reservoir damage mechanism,optimize the low damage strong inhibition of non dual poly drilling fluid infiltration, and recommendorganic salt effect of reservoir protection good degradable drilling fluid and biologic completion fluid。According to the drilling fluid temperature resisting fluid loss performance, suppression, reservoirdamage evaluation of indoor experiments, the experimental results show that, impermeable optimizeddouble poly drilling fluid has the advantages of high temperature stability, low filtration, anti-sloughingability is strong, can block the formation pore effective, non-invasive after optimization double polydrilling fluid shale recovery rate was92.22%,8h linear expansion rate10.51%, dynamic permeabilityrecovery reached more than80%, improve the drilling fluid inhibition and reservoir protection effects。...