MULTI-DOMAIN INTERPRETATION WHILE DRILLING UNRAVELS CHALLENGING DEEPWATER LAMINATED PAY RESERVOIR

摘要

Turbidites are created by gravity flows consisting ofsuspended sediments of various grain sizes. As theflow runs out of energy and declines in velocity, thesediments are deposited with the coarser grains fallingout first, and the finer grains progressively depositingtoward the top, creating laminations of alternating,fining upward sequences of sand and shale. Thecoarser grain laminated sands provide excellent lateralreservoirs, and the fine-grained layers provide seals.Net-to-gross estimates in these laminated turbiditereservoirs are often pessimistic using standardlogging-while-drilling (LWD) propagation resistivitymeasurements, because of suppression fromanisotropy caused by complex well geometry and asthe measured currents pass along the conductive clayrichlayers rather than through the resistivehydrocarbon-bearing sand layers. The extensive salttectonics regime in the Gulf of Mexico addscomplexity by creating numerous fault blocks, makingthe lateral continuity and apparent geometry of theselaminated reservoirs challenging to evaluate.