Study on low damage water-based drilling fluid system for shale gas reservoirs
When using oil-based drilling fluid for shale gas reservoirs,the cost is relatively high,the treatment of rock cuttings and waste drilling fluid is complex,and there are also certain environmental pollution risks.To solve these problems,a low damage water-based drilling fluid system suitable for shale gas reservoirs has been developed through a large number of indoor experiments,and its temperature resistance,pollution resistance,inhibition,and reservoir protection performance have been comprehensively evaluated.The experimental results show that the low damage water-based drilling fluid system has good temperature resistance.When the aging temperature is 140℃,the system can still maintain good rheological properties and fluid loss reduction performance.The drilling fluid system has good resistance to sodium chloride,calcium chloride and rock cuttings contamination.The drilling fluid system has a strong inhibitory performance,with a primary and secondary rolling recovery rate of over 90%for shale cuttings,and a linear expansion rate of only 8.5%after 12 h.The drilling fluid system has good reservoir protection performance and the permeability recovery value of shale core after being contaminated by drilling fluid can reach over 80%.The low damage water-based drilling fluid can meet the requirements for drilling fluid performance in shale gas reservoir drilling.
shale gas reservoirhorizontal wellwater-based drilling fluidlow damageperformance evaluation
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