Presenter
Michael Rabinovich from Bp
Co-authors
M. Rabinovich, R. Ansari, J. Bergeron, E. Soza, bp
Abstract
The Ultra-Deep Azimuthal Resistivity (UDAR) technology has fully proven itself in 1D pan-cake slow changing geology where it is now a reliable and highly valuable service. Fast and accurate workflows for pre-drill studies, real-time interpretation and post-drill analysis based on local 1D modeling & inversion algorithms are established by the service provider and verified by operators in real well applications and in numerical studies using synthetic models. Several academic institutions and geosteering software companies also provide access to UDAR 1D modeling and inversion algorithms.
Infill wells in mature fields are often drilled in 3D environment. For example, operators regularly are looking for cheaper solutions with less environmental footprint by accessing multiple fault blocks with one horizontal well. A local 1D inversion (sometimes called as 1.5D) which is a standard real-time processing for all service providers is inadequate in intervals with 2D/3D effects such as faults with significant throws. It will create major artifacts and blind zones in 1D inversion images in intervals around the faults which, unless properly modeled and understood at the pre-drill study stage, could lead to wrong geosteering decisions. Ideally, applications of the more advanced 2D / 3D inversion algorithms could mitigate these problems, but currently available multi-dimensional inversions are limited in accuracy, resolution, speed and must also be properly examined at the pre-drill study stage.
Based on our experience and growing scope of work in industry, we strongly believe that to facilitate these 1D and 2D/3D pre-drill studies in 3D environments, standardized 2D/3D forward modeling and inversion workflows must be developed, and they should include:
- For pre-drill studies:
o Streamlined and convenient workflows to populate and extract detailed geoelectrical models and trajectories from subsurface software such as Petrel.
o User-friendly interfaces to build simplified 2D/3D catalog models.
o Efficient, parallel, and accurate 3D modeling algorithms for simulating UDAR pseudo-raw data.
o Detailed validation of vendor’s forward modelling software to understand limitations and accuracy or limit usage to pre-validated softwares.
o Access to vendors’ standard 1D inversions to study and understand 1D inversion artifacts in 3D models.
o Advanced 2D/3D inversion results in synthetic 3D models.
- For real time geosteering:
o Catalog of 1D inversion results in a predefined set of simplified 2D/3D models.
o 1D inversion should constantly output a. uncertainties b. misfits c. 3D indicators.
o Geosteering engineers should be trained to recognize 3D artifacts in 1D images.
o 2D/3D inversion algorithms that have been verified on synthetic data and could be run in real time.
We recognize that developing accurate, fast, reliable and user-friendly 3D modeling workflows is a technically and financially challenging enterprise for each individual company, so we strongly believe that collaboration between operators, service providers and academia in the form of consortia and SIGs (such as UT 3DEM and SDAR) is necessary for facilitating these efforts and for creating benchmarks, sharing public domain UDAR information, developing and verifying 3D modeling codes.
In the paper we are going to show an example of UDAR application in 3D environment, as well as some inversion images in synthetic 2D/3D catalog models.
Biography
Michael B. Rabinovich received his MSc degree from the Moscow Institute of Oil and Gas industry and his PhD degree from the Russian Academy of Science, both in Geophysics. From 1994 to 2011 he worked as a research and senior scientist and a Deputy Director for the Drilling & Evaluation Research in Baker Hughes in Houston. He participated in the development of the processing and interpretation software for all modern wireline and LWD resistivity tools. Since February 2012 he has been working at BP as Senior Subject Matter Expert in resistivity and electromagnetic log measurements providing consultancy support to BP’s assets around the world in tool technology selection, interpretation and geo-steering applications He is an author/coauthor of more than 100 publications and 44 patents.