The Technology Of Nitrogen Foam Unbalanced Drilling Horizontal Wells In Daniudi Gas Field

As gravity of the situation of the world's oil and gas industry exploration and development, underbalanced horizontal well demand more and more urgent. According to the geologic characters, aiming at the explorative difficult problem of gas reservoir's low pressure and low permeation in Daniudi Gas Field , reservoir we have developed the research of nitrogen foam under-balanced drilling technology in Daniudi Gas Field gas reservoir .This article started from the gas reservoir's character , studied the gas reservoir damage principle and protection measures of the Shehezi stratum, put forward the protection measures of the Shehezi stratum . On the base of the relative achievements of nitrogen foam under-balanced drilling carry drillings theory of abroad and home ,We used multi-phase flow theory and method , set up the theoretic annular space flow of natural foam under-balanced drilling , and solved the model by making use of mathematical method . The foam using on the working area to the existing API standard test , drill using experimental , propose vesicant and BHA which are fit to the working area .We also have researched the safe drilling technology of under-balanced drilling , put forward the equipment program on the surface and technological progress of nitrogen foam under-balanced drilling , and arranged to compile safe drilling rules of nitrogen foam under-balanced drilling . By doing such we formed preliminarily the nitrogen foam under-balanced drilling technology witch was applicable to the low pressure and low permeation reservoir in Daniudi Gas Field , which is expected to realize the nitrogen foam unbalanced drilling technology can be applied industrially in Daniudi Gas Field .