New Logging Interpretation Methods And Techniques For Petroleum Exploration In Kuche Foreland Basin In Tarim

The geological conditions are extremely complicated in Kuche foreland basin in Tarim, where the geological structure is dominated by all kinds of thrust-fold styles, the formation dip angle changes from 0 degree to 90 degree, the tectonic terrestrial-stress is intensely compressive and the reservoir bed is primarily in low porosity and low permeability which micro-fissures often occur. These complexities have brought about great difficulties in seismic prospecting, logging acquisition, reservoir description and hydrocarbon evaluation, therefore resulted in a high risk of petroleum exploration in the area.Aimed at these difficulties, new logging interpretation methods and techniques have been investigated to meet the demands for oil and gas exploration in the area. These method and techniques are included as followings:1) Tracing interpretation and prediction for geological structures along well during drilling.Based on appropriate data-processing and geological interpretation of Dip Log or Borehole Imaging Log in the course of drilling, the geological structure is determined and the local structural position at which the drilling well is reaching can be predicted by integrating the superiority of logging data and seismic data. Thus advices to optimize the parameters for seismic data processing or advices to adjust the drilling well position can be put forward, therefore the risk of exploration is decreased to a minimum. It has been proved that this method and technique is practical and effective in Kuqa foreland basin petroleum exploration.2) Logging qualitative and quantitative evaluation of Terrestrial-stress and its geological applications in the foreland basin.The terrestrial stress has a great influence on reservoir quality of the piedmount tectonic belts of foreland basins The characteristics of shale, in particular shale resistance can easily reflect the state of terrestrial stress. This characteristic can be used to evaluate the terrestrial stress qualitatively and quantitatively. The preciseness of the method was proved by comparison the calculated stress with the result obtained from Acoustic Emission experiment. Based on the terrestrial stress analysis on a single well, the relationship between terrestrial stress distribution and reservoir distribution was determined. The effect of terrestrial stress on reservoir quality and the relation of local terrestrial stress with structure styles were investigated. The research results show that the high-quality reservoir always coincides with the relatively low terrestrial stress zones.3) Identification method of natural gas reservoir.Both conventional logging and new method logging responses to natural gas reservoir are analyzed. In particular, the effectiveness and sensitivity of logging responses to low-porosity and low-permeability reservoir is discussed, therefore some appropriate identification method of natural gas reservoir are brought forward.