Sourceless Well Placement and Formation Evaluation with Logging While Drilling Technologies

Abstract

Abstract Nuclear magnetic resonance (NMR) and acoustic logging while drilling (LWD) sensors have recently been used in a bottomhole assembly (BHA) to evaluate the viability of sourceless formation evaluation in comparison to density-neutron data subsequently acquired in a wipe run in the same well across a clastic sequence. Borehole deterioration and significant pore pressure variations across this sequence pose wellbore stability risks during the drilling phase, which have historically required the drilling of deviated pilot hole sections for evaluation purposes, which were then plugged back and sidetracked. Previous experiences in the same geological setting encountered extreme borehole enlargements. LWD helped to bypass this issue and to acquire high-quality data before borehole enlargement occurred. In addition, indications of the presence of possible rock anisotropy were observed and rock mechanical moduli were derived. The results were then correlated and matched to the offset well data, as well as with existing field geomechanics knowledge. LWD NMR and azimuthal acoustic tools, free of radioactive sources, were run in an LWD tool combination, with the primary objective of measuring porosity, pressure prediction, and possible anisotropy using a centralized four-axis acoustic caliper. This paper discusses planning, designing, and drilling using LWD NMR and azimuthal acoustic tools in this well. It also describes the viability, integrity, and robustness of logged data, as well as the interpreted results. The optimization of real-time drilling operations and petrophysical data acquisition requirements are also investigated to help improve future field development and overall reservoir management strategies.