Abstract:

Resistivity logging while drilling plays an important role in logging while drilling. Resistivity logging while drilling is affected by such environmental factors as borehole(hole diameter,mud) and shoulder beds (high resistivity or low resistivity shoulder beds), its logging value is always different from actual formation resistivity. The environmental factor correction of logging curves while drilling mainly uses chart correction method. The correction chart is made based on theory calculation or experiment result , it is not suitable for successive comprehensive environmental correction on all well segment formation. Schlumberger、Haliburton and Bakerhuges shoulder bed effect correction charts on resistivity logging while drilling made by the three companies are used to study on the relationship between resistivity logging values while drilling and shoulder bed resistivity, bed thickness and sampling and reading value on charts, and adopting neural network to match optimally, to gain correction formula, developing programs to realize automatic correction on shoulder bed effect in resistivity logging while drilling, all these show that ,the result gained with this method is rational, and the correction effect is evident.

Key words: resistivity logging while drilling, correction chart, shoulder bed, thickness, neural networks