Gas Drilling While Drilling The Reservoir Evaluation

The reservoir application of Gas Drilling is a new technology developed in the late 20th century. Because Gas Drilling can get a high ROP with small cost, can eliminate bad lost circulation, can reduce the formation damage effectively and achieve the maximum deliverability, it has been playing an important role in oil and gas exploitation.It has crucial importance in oil and gas exploration to find hydrocarbon zone and to take knowledge of the reservoir physical property in time in drilling process. In routine overbalanced drilling, the bottom hole pressure towers above the formation pressure so that the mud fluid will leak into the formation. Because the formation fluid can not seep in well bore, people find out reservoir usually by cuttings logging, gasometry logging, core analysis, fluorescence etc. But it needs Drilling Stem Test to get reservoir off-take potential and formation parameters.For Gas Drilling, the bottom hole pressure is far smaller than the formation pressure, so that the gas in the reservoir come out to the hole continuously and get out of the well. This flowdrilling carries abundant information of the reservoir encountered. By researching the collecting, processing and interpreting the information, the reservoir can be evaluated dynamically during drilling. So Test While Gas Drilling (TWGD) can either play an important role in oil and gas exploration.This thesis mainly aims at Test While Gas Drilling. The main contents and the corresponding results are as follows:· The important base of TWGD interpretation is to predict the physical field parameters of the complex flow in the wellbore. To get the properties of the gas in the annular space and the pressure of the bottom hole, a group of models were constructed in this thesis.· A correct model is crucial important to the TWGD. The seepage model is the bridge between properties of reservoir and the gas in annulus. So only a correct model can reflect properties of reservoir accurately. After taking enough account to the character of flowing near the well bore, a unitive seepage model of Darcy flow and non-Darcy flow...