This paper presents a methodology which allows performing a real time characterization of the conductive natural fractures permeability intercepted by the bit while drilling. Such fractures are detected by monitoring continuously flowing from the wellbore into surrounding formations and the mud losses at the rig-site using flow-meters measuring both the ingoing and the outgoing mud flow. Moreover, when drilling naturally fractured reservoirs, mud loss data provide one of the most effective means to assess the existence of conductive fractures intercepting the wellbore and therefore to identify potentially producing intervals. The patterns in the variations of these volumes are analyzed to identify open fractures. The advanced Flowmeter has increased the resolution of the mud flow measurements. It has enabled the authors to assess the flow quantitatively and relate mud flow anomalies with the presence of open fractures down hole in the trial exploratory well. The mud flow anomalies were validated with surface drilling parameters and gas indications. It was observed that the open fractures were associated with increase in torque and gas indication. The mud flow anomalies also provide crucial information for early kick or losses detection in high pressure gas wells because a better accuracy and a quicker response in detecting kicks and losses can be achieved by monitoring the changes of the mud flow rate by using flow meters measuring the inflow and the outflow mud rate, respectively. Method and Theory The most commonly used techniques to detect the mud losses consist in monitoring the level of the mud pits with acoustic, floating sensors and/or using paddles set inside the flow line that measure the return mud flow rate with a small degree of accuracy. The traditional Flowmeter provides a simple qualitative fluctuation in mud flow. In contrast this advanced Flowmeter works on the principle of converting mudflow out in to an analog signal which represents the volume of mud.

This paper will present an innovative new methodology for realtime monitoring of bit condition – and hence drilling efficiency - using surface measurement of alkene gases artificially created at-bit by the bit as its condition deteriorates. A drop in ROP can be an effect of a variety of causes, often disparate in nature. Can performance be improved by a change in drilling parameters and, if so, for how much further will these parameters remain effective? Is there some form of drilling dysfunction that is resulting in inefficient transfer of energy into drilling action? Is there a change in lithology and, if so, is the bit still appropriate and viable in this new formation? Or is the bit simply approaching the end of its useful life through wear earlier than anticipated, in which case at what point does it become less economic to continue drilling at low ROP and POOH instead? The decision to POOH to change a bit that is perceived to be under-performing can be costly if the bit is found to be in workable condition and the trip is therefore premature. Unnecessary trips are a major source of non-productive time (NPT) so any trusted source of indicative information on bit condition adds valuable context and confidence to operational decision-making. Realtime monitoring of contaminant alkenes provides timely indications to drillers of the degree of bit wear, mitigating invisible lost time (ILT) through excessive prolongation of an ineffectual dulled bit run, and reducing the risk of its potentially catastrophic failure. Field-based case histories are presented supporting the complementary relationship of alkene generation to other indicators of inefficient drilling, how alkene presence can assist in drilling dysfunction diagnosis, and a prototype of a software application based on alkene levels that informs decision-makers of the ‘tipping point’ at which objective commercial factors support pulling a dull bit.

Development, delineation and appraisal wells drilled in high pressured, naturally fractured Jurassic reservoirs of West Kuwait are exposed to the risk of "well kicks" and "mud-losses". The risk becomes greater due to differential reservoir pressures, presence of naturally open fractures, and narrow pressure window between formation-and fracture-pressures. In many instances, "alternate loss & gain scenario" ensues and the well control options become limited, occasionally, further drilling becomes impossible leading to temporary suspension or even termination of the wells. This causes safety issues and large loss of rig time and money.

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Realtime Wellbore cleaning and stability Monitoring Service has been deployed in the field, where several side-track wells had been drilled due to stuck pipe and consequent lost in hole equipment. Traditional drilling practices were to drill highly deviated wells with inconsistent ROP without having sufficient information about the borehole condition and with the narrow pore pressure margin, which regularly resulted in sustained losses, even leading to differential sticking. In addition to these challenges, the well geometry made it necessary to constantly maintain sufficient ECD sensitive to borehole condition. The service consists of Advance cutting flowmeter measuring cumulative bulk solids recovery while drilling, along with sophisticated software application compensating for drilling fluid coating the cutting. The real-time delta between actual and expected cutting volumes in surface is therefore a direct indicator of borehole cleaning efficiency and thus compared with various drilling and hydraulics parameters to provide timely operational recommendation, optimizing drilling performance and pre-empt potential causes of NPT/ILT. The service is successfully determining the maximum allowable ROP in relation to cutting recovery, optimizing the number of drilling fluid pills, and supporting torque and drag analysis including cutting effects to give early indication of potential stuck pipe. This has reduced the on-bottom circulation cycles, reaming time and tripping intervals; thus allowing to drill longer deviated or horizontal sections avoiding tripping to clean the borehole. As a result, operator was able to drill the wells optimally; saving 3.5 days of rig time, and about 50% of the pill volume for each well. The total cost saving for 5 wells, with the service deployed mostly in 6" production section was USD – 1.075 Million. The solution has then deployed across multiple rigs, drilling similar challenging wells.