Logging Evaluation Study Of Tight Gas Sandstones Reservoir

As one of the unconventional hydrocarbon reservoirs, the tight gas sandstone reservoirhas low permeability and low porosity, which make it more difficult to the logging evaluationand logging interpretation. The reservoir evaluation and description is not only the keytechnology issue but the core technology issue. In terms of physical Characteristics andLithology of the low permeability and porosity and medium high permeability and porositytight gas sandstone reservoir there are many differences. Due to low permeability andporosity of the tight gas sandstone reservoir, the reservoir fluid makes few effects on thelogging response and it is mainly limited by the borehole and some other external factors,which makes parts of the logging information responding to the formation distorted, so thelogging fluid identification and evaluation of the low permeability and porosity reservoirsbecomes more difficult.In the paper, we start with the research of the geological features of the tight gassandstone reservoir, which is based on the core and Petrophysics experiment, and propose aninterpretation method in which combined conventional logging data and nuclear magneticresonance logging data according to the different characteristics of the low permeability andlow porosity reservoir, in addition, we established a interpretation model whose parametersare permeability, porosity and water saturation and so on. By comparison and in-depth study,we concluded the advantages and disadvantages of the quantitative analysis method andqualitative analysis method then chose a better evaluation method of low permeability andlow porosity tight gas sandstone reservoir. After all these done, we calculated the porositymodel for the Ordos and Junggar Basin tight gas sandstone reservoir using the densityunited with MRI method, and calculated the permeability model using the BGMR methodand also water saturation based on capillary pressure, then we compared these methods withthe conventional interpretation methods and analyzed how these methods affected theparameter calculation accuracy of the tight gas sandstone reservoir and its applicationresults.In the course of the study of logging evaluation of the tight gas sandstone reservoir, by fully using the conventional logging data, NMR logging data and coring data in the Ordosand Junggar Basin area, we have conducted those methods and made comparative analysis.We get some research findings and get better results in the interpretation model andevaluation method which is tested on the Ordos and Junggar Basin reservoir and is appliedto the actual logging data. This shows that the methods above are applicable for the practicalapplication.