Designing and Validating 2D Reservoir Models
- Troy Thompson (Saudi Aramco) | Jay Vogt (Saudi Aramco) | Yan Zaretskiy (Aramco Services Company)
- Document ID
- Society of Petroleum Engineers
- SPE Kingdom of Saudi Arabia Annual Technical Symposium and Exhibition, 24-27 April, Dammam, Saudi Arabia
- Publication Date
- Document Type
- Conference Paper
- 2017. Society of Petroleum Engineers
- 2 in the last 30 days
- 66 since 2007
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2D Conformal Modeling (2DCM) is a ground-breaking technique for building and maintaining 2D structural frameworks, especially with the existence of high-angle horizontal wells. 2DCM is proposed as the standard tool for accurately and efficiently interpreting horizontal wells and constructing frameworks. The 2DCM workflow has been developed and refined over the past 10 years using thousands of horizontal wells in active development areas across a wide region. In addition to accurately representing the geological observations along the entire horizontal well, it is a very efficient method that enables interpreters to update their models while drilling and to accurately incorporate intra-formational observations. This enables truly “living” models that serve as the front end to reservoir and fluid modeling, forming the basis of a Live Earth Model.
The industry practice of iso-gridding and flexing to create structural grids using data from vertical wells has been around for many generations, and results have been excellent. Many fields, however, are no longer in the age of vertical wells but rather in the age of high-angle deviated wells. Can we assume iso-gridding and flexing techniques for high-angle deviated wells will also lead to excellent results? How do we determine what are excellent results? Perhaps it is better to look at this from the Reservoir Engineering perspective where fluid flow is paramount and reservoir grid shapes must honor the borehole. If 2D models are the foundation for 3D structural frameworks, it is imperative that the structural grids reflect the correct position relative to the borehole. Simulation and history matching will be greatly improved if the reservoir geometries are correct relative to the borehole. A horizontal borehole with a 100% net/gross reservoir contact, yet lying partially outside the 2D modeled reservoir zone, will obviously yield poorer results in fluid flow simulation.
The Age of Vertical Wells covers most of the history of O&G exploration and development and rapidly transitioned to the Age of Horizontals around the turn of the century with the strategic shift toward high-angle lateral wells for field development and the advent of interpretation-quality downhole logs provided by LWD. Prior to this shift, 2D structural framework models and 3D numeric geological models were easily and accurately constructed using vertical wells. The industry standard techniques (e.g. isochore stacking, grid flexing) for constructing these models, however, usually fail when attempting to incorporate observations and interpretation from high-angle lateral wells. 2D Conformal Modeling (2DCM) is a new technique that allows all observations for all wells to be incorporated into the construction of high precision, accurate 2D structural framework models, which in turn form the foundation for 3D numeric geological models. 3D numerical models not incorporating this technique will inevitably lead to poorly defined structure models, relative to the high-angle wellbores. This in turn leads to improper numerical property distributions and the eventual poor history-match of fluid simulation models. It is an imperative that the stratigraphic framework (the “tank”) be defined and accurate by honoring all of the data of the wellbores before any meaningful answers can be wrought from 3D numerical stratigraphic and fluid modeling.
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