Reservoir Characterization through Automatic History Matching of Underbalanced Drilling (UBD) Data in a Horizontal Well

Abstract

During under-balanced drilling (UBD) of a horizontal well, down-hole pressure and temperature, as well as surface rate and pressure data are acquired. Theoretically, estimation of reservoir permeability profile can be achieved by quantitative analysis of these data. However, in practice, not only is a fine-grid reservoir simulator required to simulate the drilling schedule change due to tripping, completions, workovers, increase of well length with drilling and fluid flow in reservoir, but also an effective inversion approach is needed to estimate the reservoir parameters. The problem of reservoir characterization using UBD data has been studied by several previous workers. At current state of the art, neither analytical models nor commercial reservoir simulators are completely suitable for modeling the coupled system of UBD and reservoir fluid flow.In this paper, we focus on the development of an automatic history matching technique to interpret the measured oil rate and down-hole pressure data while drilling. Our contributions are three fold. Firstly, a two-phase 3D reservoir simulator was developed in which the UBD drilling process was coupled into the reservoir simulator. Next, the reservoir simulator is applied to simulate the entire drilling process from penetrating the pay-zone until the well is complete. Secondly, a least square method is applied to match the down-hole pressure and oil rate data. The inversion for a synthetic UBD data set and realistic UBD data are demonstrated on a multi-zoned reservoir model. The results show that permeability and initial reservoir pressure can be obtained by matching down-hole pressure or oil rate in a short time of exposure to the reservoir section. Finally, we offer the details for implementing the UBD process in the simulator and discuss the practical issues of the application of UBD data in reservoir characterization through this automatic history matching technique.

Under-Balanced Drilling: A Game-Changing Technology for the Development Strategy of a Giant Carbonate Reservoir

“…It is this data that is used in the advanced analysis stage to construct the RIPI plot. Further details on the subject are noted in the references [4][5] . The application and results of this process from our field case will be provided in depth in the following section.…”

“…Several professionals investigated different methods to perform the analysis which are documented in the references [4][5][6] . The acquisition and interpretation of FWD data utilizing transient analysis techniques to estimate reservoir parameters play an integral role in enhancing the understanding of the dynamic nature of the reservoir.…”

“…This paper will explicitly describe the details of the last pilot drilled for well-X where Real-Time geosteering was actively used to account for changes in the reservoir architecture, as well as the successful application of "Real-Time Reservoir Characterization (RTRC)" process developed by Blade Energy Partners [4][5] . Description of the data analyses & results acquired will be presented, highlighting the significant value derived in terms of improving reservoir understanding and its impact on the projected field development strategy.…”

Reservoir Characterization Begins at First Contact With the Drill Bit

“…The added benefit of using a numerical simulator is the potential for incorporating behaviors of neighboring wells, in addition to handling pre-and post-UBD history. Numerical simulation for reservoir characterization during UBD was also described by Vefring et al (2002Vefring et al ( , 2006, Biswas et al (2003), and Wu and Suryanarayana (2011). They described 2D and 3D twophase reservoir-simulation approaches, with Wu and Suryanarayana (2011) offering an automated-history-matching capability.…”