An Efficient Workflow for Geological Characterization in Unconventional Reservoirs From a New Through-the-Bit Logging Electrical Micro-Imaging Tool

Abstract

It has been proved that the well production in unconventional reservoir has been controlled by the reservoir quality and completion quality. The lateral heterogeneity is influenced by the structural complexity, fracture distribution, and facies changes. The fracture evaluation is one of key elements for completion design and multiple stage hydraulic fracturing operation. The high-resolution borehole image has been proved as the effect tool for fracture evaluation. We propose a solution for accurate fracture evaluation with structural delineation in unconventional reservoir after picking dip from a novel borehole resistivity image. The horizontal well is very common in unconventional reservoir; the bedding boundary is paralleling to well trajectory in most case. It is difficult to picking bedding boundary as sinusoid in such case. A true-dip plane based dip picking is innovated and applied with this new borehole resistivity image for bedding boundary picking as different shapes, such as bull’s eye, reverse bull’s eye, paralleling features etc... The lithology bound fracture can also be picked and classified with this method to have more accurate statistics in different zones. Fracture aperture computation from this new image is also verified with another well-known borehole resistivity image in same well. Although the structure in unconventional reservoir is relative flat in most case, there are still many small-scale varied structures and faults controlling the fracture distribution. The near well structure can be reconstructed from the bedding boundary and fault with an improved structural modeling method; and then the relationship between fractures and structures & faults can be analyzed for completion design. The breakout and drilling induced fracture can be confidently identified from this new image; and then stress regime can be constructed for hydraulic fracturing design. A case studie was used to demonstrate this solution from shale gas reservoir of Anadarko Basin, Oklahoma, U.S.A. The good understanding of fracture distribution and structural delineation provides valuable information for completion and hydraulic fracturing design in this well and continuous new well design.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018