STAVANGER OCTOBER 2007 MEETING

Quality Airport Hotel, Stavanger

Note the venue change since before the summer

Wednesday, 3^rd October, 2007, 11:00 a.m.

Lunch will be provided at 12:00

Correlation and Sedimentary Steering to maximize well placement certainty in mature reservoirs while drilling

by Dr Jeremy (Jez) Lofts, 2007 SPWLA distinguished speaker

Abstract

Electrical borehole images offer a unique view of the subsurface to geologists and petrophysicists. Images from traditional electrical imaging tools are readily interpreted in terms of key geological characteristics such as structural and stratigraphical features of the formation and today, high resolution electrical images are available while-drilling. The drilling environment surprisingly, offers an ideal platform for electrical borehole imaging. At the time of drilling, the borehole wall rugosity is often minimal and electrical images generated by sensors that rotate with the drill string provide a full coverage of the borehole (when compared to the pad coverage observed on conventional wireline borehole images). It is also an opportunity for real-time geological analysis and ultimately decision making that can reduce rig-time and vastly improve reservoir net hydrocarbon. Images sent to the surface give an early indication as to the angle of entry into a given formation and allow for a more accurate/precise geosteering and possible geomechanical information that may mitigate drilling hazards. This presentation reviews the advances in resolution and application of a while-drilling resistivity imaging technology through a variety of case examples.

• Structural and geomechanical features are documented including micro to macro faulting, composite fractures, fracture clusters and swarms, induced fracturing and breakout. Features imaged “While-drilling” are often comparable to wireline resolution and additionally, whilst often a greater understanding of the geological features is often possible because of the full circumferential coverage. Real-time structural information provides earlier drilling related decision making.
• A broad range of high resolution sedimentary features allows textural analysis and facies discrimination and feature orientation for sedimentological application not unlike traditional image interpretation. This analysis is extended to the real-time environment where the concept of Sedimentary Steering is introduced. This is the ability to use detailed high-resolution features for advanced Reservoir Navigation (geosteering) with a predictive and real-time interface. It is focused around reducing uncertainties related to, and improving geosteering within the desired “sweet-spot” of a variety of clastic and carbonate reservoirs. The concept is introduced and illustrated.

To finish. A discussion will end the chapter on the minimum useful resolution for sedimentary steering including the different features that can be determined and hence what telemetry constraints are likely for sedimentary steering and real time structural analysis.

Dr Jeremy (Jez) Lofts, CV

Dr Jeremy (Jez) Lofts received his PhD from Leicester, UK in 1993 and he is a Chartered Geologist. He has worked as an image interpretation specialist and lectures externally/internally on the subject of Borehole Image Interpretation. Jez is author of +25 papers on geological and petrophysical oilfield applications and is SPWLA 2007 Distinguished Speaker. His coauthored paper (Ritter et al 2004) on StarTrak won best paper in Petrophysics for 2005. He is currently the Director for Formation Evaluation Product Lines (LWD-Coring-Surface logging) at INTEQ (a division of Baker Hughes). He is currently also Honorary Industrial Associate and Lecturer at the University of Leicester, UK, Department of Geology.