Abstract
We are today moving into deeper seas and more challenging areas for finding oil and as the quest continues we enter more areas with uncertainties and possibilities of greater disasters. Very soon, if the technological advancements lag behind, the price of a crude barrel might not cover for the risk that the explorers take for it. Having said that, there is a very crucial balance that we need to strike in terms of long term investments for better efficiency vs. the cost effectiveness of our systems. Risk especially in regions of exploratory drilling is very high and this paper deals with a technology of downhole mud evaluation for predicting the entrainment of formation fluid into the wellbore. The innovative kick detection system proposed in the paper uses a small mud rerouting section just above the BHA after the LWD and MWD tool. The small section of the mud into the tool is passed from between two plates (of metal with v.high melting point and definite resistance curves at HPHT conditions) that are separated by a small distance and have a definite known (corrected) potential applied across them. As soon as there is entrainment of formation fluid bubbles/droplets into the flow, the medium between the two plates will undergo alteration (change in absolute mud parameters) which will result in a change in capacitance between the two plates that can be detected immediately using the currently available technology. This change in potential can be coupled through a coil in order to produce a magnetic impulse that can easily be carried to surface and registered as a ‘count’ of abnormality in fluid. Greater the count more will be entraining fluid and hence a kick can be detected. For very fast flowing fluids, we can incorporate high temperature potential measurement systems that can help us quantify the capacitance between the plates and tell for certain whether or not a kick is present. The tool can be calibrated for specific mud type used and the fluid behavior at down-hole conditions giving us a more accurate measurement. Limitations of this technology might lie in the materials used for electronics development and type of transmission system in place for the signal to reach to the top in very deep wells but there is an added benefit of quantitative and definitive measurement.