Underbalance Coring Tool Design Research And Field Application

Buried hill reservoir in Liaohe oil region reservoir for fractured reservoirs and failure, severe leakage of oil and gas reservoirs. Reservoir pressure and production is low, there is a big difficulty of exploration and development. Buried hill and low pressure drilling in deep low permeability reservoir fracture development low pressure low formation, because of well leakage occurred in oil and gas well production is extremely low, the need to adopt underbalanced drilling technology for reservoir protection, reduce the poor fracture development low pressure formation leakage of drilling fluid to reservoir damage. In order to obtain the underground core data, need a coring in underbalanced drilling. Using underbalanced coring technology will be more intact rock cores obtained the original porosity, permeability, saturation, etc., for the analysis of the formation physical properties to provide a more accurate geological data.Underbalanced drilling technology is the eye drops in the formation pressure is greater than the column under the pressure of a special drilling technology, to truly achieve the purpose of protecting reservoir, underbalanced drilling technology must implement the whole process of underbalanced drilling and well completion and put into production, as the supporting technology of underbalanced drilling coring technology also arises at the historic moment. Referred to in this article the underbalanced drilling coring technology refers to the drilling fluid(gas) as a circulation medium of underbalanced drilling under the condition of a special coring technology, use the coring technology for core will more fully reserves the original rock porosity, permeability, saturation, etc., for the analysis of the formation physical properties to provide a more accurate geological data.Through underbalanced coring technology not only can improve the core recovery of under the condition of underbalanced drilling and single cone penetration, is beneficial to obtain the real geological data, and alleviate the drilling damage to reservoirs. Low pressure area of Liaohe oilfield layer of low permeability fractured reservoir exploration and development has important practical value."Under-balanced drilling coring technology research" project completed the underbalanced drilling coring technology research, proposed the implementation of under-balanced drilling coring difficulties, completed the underbalance coring tools and the development of the drill bit, and tools for the stress analysis and strength check, carry out the underbalanced drilling coring technology research, compiled the underbalance coring operation procedures and contingency plans. Complete Φ 215.9mm underbalanced coring Wells eyedrops phase field test 7 Wells, the coring 8 cylinder, penetration of 25.19 m, 22.38 m long, heart average core recovery of 88.84%; Complete Φ 152.4 mm underbalanced coring Wells eyedrops phase field test 4 Wells, the coring 6 cylinder, penetration of 14.80 m, penetration of 10.20 m, the average core recovery of 68.92%. Gas drilling coring tool 1 well field test, coring barrel 3, penetration of 10.84 m, 6.25 m long, heart harvest rate is 57.66% on average.