GTILT PLUS provides all the features of GTILT, along with extra features for advanced users. The additional features include:
SPIRAL CORRECTIONS
GTILT PLUS includes a copy of the GSPIRAL utility, which handles data from an incremental spiral tool in the same way as GTILT handles inclinometer data. GSPIRAL calculates casing twist versus depth, and can write spiral data files suitable for importing into GTILT PLUS.
GTILT PLUS can incorporate spiral data into the .GTL file in which it stores the normal inclinometer data. However, the two types of data are kept separate within the file. GTILT PLUS also contains an editor for the spiral information, which is expressed in the form of degrees of cumulative twist at each reading depth. This not only allows easy checking of data, it also means that twist information can also be entered directly into GTILT PLUS, without the use of GSPIRAL. This is important if the information comes from a source other than an incremental spiral sensor.
GTILT PLUS has a toggle which allows spiral corrections to be turned on and off. If the spiral correction is on, and spiral data is available, the correction will be applied and the plots annotated accordingly.
ACCELEROMETER ROTATION AND ZERO SHIFT
GTILT PLUS allows corrections to be applied to compensate for accelerometer rotation about a vertical axis and also for zero shift between readings in different directions. Each set of readings and each direction (A and B) can have different corrections for each parameter.
STATISTICAL DATA SUMMARY
GTILT PLUS can make a statistical summary of inclinometer data, helping specialized users to spot instrument errors. This is over and above the checksum histogram feature which exists in GTILT.
COMPENSATING FOR SETTLEMENT
Where significant settlement is expected, inclinometer casings are often installed with telescoping joints to prevent the casing from being crushed longitudinally. This not only extends the life of the casing, but also may allow settlements to be monitored at various depths. GTILT PLUS can use recorded settlement profiles to correct for reading depth errors caused by settlement, without requiring complex and error-prone field protocols involving manual adjustments to actual reading depths. Another advantage of this approach is that corrections can be applied even in cases where there were originally no plans to allow for the effects of settlement.
This type of correction can also be used to compensate for the effects of using different cables in deep holes. It can also be used to correct a depth offset in the dataset, as happens if readings are taken at odd-numbered feet where even-numbered readings are required. (It is of course better to take the readings at the correct depth in the first place.)
CONVERTING TO METRIC
If you have an installation which has been read using a probe with a 2 ft wheelbase for many years, the simplest and most accurate course of action is to continue using a 2 ft probe. However, sometimes there is a good reason why a switch to a 0.5 m probe is desirable. GTILT PLUS now includes a "Metric Conversion" function which estimates what the readings of a metric probe would have been, had it been used rather than the 2 ft probe. If you have datasets taken on the same occasion with both probes, the accuracy of the conversion can be further enhanced by using the "Force Match" feature.