LogScope has the ability to interactively using gestures drift correct any curve such as the SP. The video below shows this in detail.
The first step is to select the curve. In this case we select the Spontaneous Potential (SP) curve as shown in the screen shot below. It places a red line at 0 MV and the black dots represent the points that need to be adjusted to read 0 MV. Tapping on a point a second time will delete it.The red line can be adjusted by tapping on it and sliding it left or right.
When satisfied with the drift correction just press the process button in bottom left hand corner.