METHOD OF CONSTRUCTION OF OIL-GAS WELL Russian patent published in 2003 - IPC

FIELD: construction of oil and gas wells, particularly, their flushing and protection of sweet underground waters from contamination with drilling mud. SUBSTANCE: method includes, prior to drilling wells of service water supply, sampling of water from present local open water reservoirs and testing for safety as regards its epidemic characteristics, and revealing the most safe water reservoir. For drilling wells of service water supply, use is made of drilling mud on base of preliminarily disinfected sweet water from local open water reservoir formed with ecologically clean underground waters identical or close in its qualitative composition to sweet water horizons drilled in upper part of geological section. Water is tested for its correspondence to hygienic standards, and in case of negative results, water is subjected to chlorination. Before preparation of drilling mud, disinfected water used for the purpose is tested for content of residual chlorine. Water from wells of service water supply is used for drilling underlying rocks after lowering and securing of surface casing string. EFFECT: higher epidemic safety of well construction due to prevented bacterial contamination of sweet underground waters in drilling wells for service water supply and oil-gas well for surface casing string.