DCI Drilling Complexity Index
The Drilling Complexity Index (DCI) developed by Wintershall indicates the level of complexity of a well on a scale of 1 to 10 – the more complex the well, the higher this value.
Many factors determine how difficult the well is, for example the rock properties, the depth and the type of well. These factors are incorporated into the DCI and allow the complexity of the well to be determined. The index is already used by Wintershall for all its planned wells.
The level of complexity determined by the DCI is closely linked to the probable down times during drilling: the higher the complexity, the more downtimes are likely. This way, possible obstacles can be identified before drilling begins and accounted for in the planning process.
These categories determine the DCI
What type of drilling project is it? How long will it take?
What type of rig is being used? Onshore or offshore?
Pressure & Temperature
What are the pressure and temperature readings in the rock formation that is being drilled through? How much leeway do I have with regard to the drilling fluid weight?
How many casings will be used – in other words, must be installed telescope-style?
Drilling Fluid (HSE)
Will water-based or oil-based drilling fluid be used? Will I have to specially dispose of all fluids and the well cuttings, which would be the case with oil-based drilling fluid?
Depth & well trajectory
To what depth will the well be drilled? How strong is the deflection? Will it have a sidetrack?
Comparing two wells
DCI & NPT Drilling Complexity Index (DCI)
NPT stands for non-productive time and describes the phases during which adrilling project does not make progress. For an NPT of 10 percent, this would be 10 out of 100 days. If you know the DCI of a well, you know what NPT to expect.