A slim azimuth 20 independent-arm caliper logging tool;

Optimal design of eccentering device for caliper and microelectrode system;

Realization of continuous inclinometer/caliper/minilog combination logging;

The influences of the hole diameter and the formation acoustic parameters on the mode waves are investigated.

Focusing on the statement that permeability can bring about little effects to CBM output,the paper has set forth two major factors affecting CBM output,i) factor created by man,which is well diameter,a very important reference,ii) the natural factor,including gas content of CBM and pressure/absorbing features of CBM,another very important reference.

The conception of optimum well diameter has been proposed in this paper.

According to the test of the relationship between well diameter and water discharge of a specific well, a suitable well diameter has been determined as 200～400mm and a key problem to utilize shallow water in the area is solved.

During coalfield well logging,the changing of borehole diameter will interfere other well logging parameters.

A quite ideal borehole diameter correction formula which has definite physical meanings has been developed by adopting geometrical factor method to make math- ematical fitting of Schlumberger Corporations borehole diameter correction chart for density logging data.

This paper,setting the parameters except the borehole diameter as known quantities,and the borehole diameter as an independent variable,work out the value of the dependent variable,the CBM producti.

Analysing the process of gaining the date in caliper logging,select the method "Sweep Representation" to build the equations of well bore model.