A comparison between 1-D, 2-D and 3-D basin simulations of compaction, water flow and temperature evolution

Abstract

Is 3-D basin modelling really necessary? The answer depends on the type of problem under consideration. The Institute for Energy Technology (IFE) 3-D Basin Simulator offers the possibility to investigate certain aspects of this issue. It is a prototype l-D, 2-D or 3-D basin simulator for reconstruction of the time-dependent pressure and temperature evolution of compacting sedimentary basins. Comparison of results, from l-D, 2-D and 3-D simulations confirms that there may be significant differences due to water flow and pressure hehaviour. The advantage of 2-D simulations as compared to 1-D is seen in overpressured configurations where 2-D allows more realistic calculations, while 1-D is less predictable. When going from 2-D to 3-D advantages are evident in configurations with pronounced 3-D basin geometries in combination with rapid processes and overpressure. The differences in water flow velocities and consequently the pressure calculations, may be quite significant. The rates in 3-D may be several orders of magnitude higher than in 2-D due to lateral focusing effects, while the overpressure still remains high. One consequence is, for example, reduced compaction in 3-D as compared to 2-D, with notable effects on basin geometry and temperature evolution of individual layers. Temperature anomalies due to increased convection in 3-D seem to be of less importance, unless processes of lateral focusing of water flow reach extreme levels.

The pore pressure regime of the northern Gulf of Mexico: Geostatistical estimation and regional controls

“…Mathematical models of fluid and sediment responses to burial began in one vertical dimension (Sharp, 1976) and extended to two dimensions for analysis of groundwater movement, petroleum migration, and ore genesis (Bethke, 1985). This foundation was further extended to 2.5-D or pseudo threedimensional (3-D) modeling, then to full simultaneous treatment of flow and the factors causing it in three spatial dimensions (Throndsen and Wangen, 1998). Finally, 3-D process analysis, when inputs change in time steps, produces four-dimensional estimates of the evolution of fluid flow and pressure in a rock volume over geologic time.…”

2D modeling of overpressure in a salt withdrawal basin, Gulf of Mexico, USA

“…Basin modeling can be used to forward model pore pressure and provides information on the timing of overpressure development (Giles et al, 1999;Throndsen and Wangen, 1998;Yardley and Swarbrick, 2000;Yardley et al, 2004). Models are typically calibrated to pressure measurements in sandstones and increasingly other well information such as log data, mud weights, seismic velocities and velocity based pore pressure calculations.…”

“…The modeling is aimed at assessing the relative importance of basin geometry, lithology, model resolution, and the sealing effectiveness of salt welds on pore pressure prediction. Three-dimensional basin models have been shown to be more robust than 1D and 2D models for pore pressure prediction since they can more accurately portray the 3D nature of fluid flow (Giles et al, 1999;Throndsen and Wangen, 1998;Yardley et al, 2004). This study used two intersecting 2D basin models due to the lack of knowledge about past salt movements and the time necessary to properly constrain a palinspastic 3D reconstruction of a basin that includes significant salt movement.…”