Sourceless Well Placement with Real-Time Acoustic Measurements

摘要

Sourceless well logging(logging without using traditional chemical sources)has become more attractive in certain locations because of evolving government regulatory and HSE requirements.LWD sonic tools provide opportunities to operators for both well placement and formation evaluation. For the first time in the UAE,an LWD acoustic tool was added to a bottomhole assembly(BHA)to acquire sourceless porosity measurements to help stay in the porous sub-layers in the target reservoir.In comparison to more traditional nuclear measurements,LWD sonic has a superior depth of investigation that is less affected by standoff and a driller-friendly BHA free from stabilizers. Based on the evaluation of offset data,which indicated excellent correlation of sonic vs.density/ neutron measurements,we decided to provide shear porosity in real time owing to the sequence stratigraphy and corresponding energy partition.A post-job comparison with density/neutron data ac- quired in a wipe run was also conducted to verify the sensitivity of real-time acoustic porosity measure- ments for both well-placement and formation-evaluation purposes.Sonic-derived porosities were found to be instrumental in the real-time decision making needed to keep the well the in higher porous sub-layers. Current developments,including real-time azimuthal sonic together with considerations of integrating acoustic and NMR measurements in both petrophysical modeling and field applications,show promise in providing reliable sourceless porosity estimation in these formations. This case history delivered a BHA free from radioactive chemical sources.Safe drilling objectives as well as maximized productivity per unit lateral length were achieved despite the potential risks associated with the faults that were observed in the pilot hole.