- Home
- Conferences
- Conference Proceedings
- Conferences
ECMOR VI - 6th European Conference on the Mathematics of Oil Recovery
- Conference date: 08 Sep 1998 - 11 Sep 1998
- Location: Peebles, UK
- ISBN: 978-94-6282-121-7
- Published: 08 September 1998
41 - 60 of 63 results
-
-
Capturing Effective Behaviour of Capillary Influenced Flow
Authors L. Allesio, P. R. King and A. D. W. JonesThis paper presents a study of porous media flow in which capillary forces have a significant impact. The principal objectives of the work are to improve understanding of the influence of viscous and capillary forces on displacement processes and to develop an upscaling method to account for the effect of small-scale (cm) contrasts in capillary pressure.
-
-
-
The Results of Testing Six Different Gradient Optimisers on Two History Matching Problems
Authors T. Deschamps, T. Grussaute, D. Mayers and R. BissellHistory matching may be viewed as an optimisation problem in which an objective function is to be minimised by selecting a set of its parameters and then varying their values. These parameters are items of data in the simulation model or the input to some pre-processor such as a geostatistical model of the reservoir.
-
-
-
Mathematic Comparison of Different History Match Runs
By C. MonicoDifferent history match runs are usually compared in reservoir simulation by observing the results on a plot. Sometimes the comparison is doubtful like when a run gives a good match for some wells whilst another run gives a worse result for the same wells but leads to a better simulation for other wells. Doubts can be present also when the simulation of a well fits a parameter in a run or a different parameter in another run.
-
-
-
Use of Sentinels for Interpreting Well Test Data
Authors M. Mezghani, F. Roggero and J. -P. RaymondThe process of determining unknown petrophysical properties in a reservoir model in order to obtain the best fit between observed well flow history and simulation results is commonly called "history matching", An important source of uncertainties in the history matching process is measurement errors, which have a significant effect on reservoir characterization.
-
-
-
Quantification of Uncertainty Reduction by Conditioning to Dynamic Production Data
Authors F. J. T. Floris and C. F. M. BosMaking decisions in reservoir management requires a method for quantifying uncertainty. In reservoir volumetrics, expectation curves for quantifying reservoir properties such as gross rock volume, average porosity, are weIl accepted. Using Monte Carlo simulation, the uncertainty in average reservoir properties are propagated to uncertainty in hydrocarbons initially in place, and eventually to uncertainty in ultimate recovery.
-
-
-
Optimal Choice of Inversion Parameters for History-Matching with the Pilot Method
Authors M. Cuypers, O. Dubrule, P. Lamy and R. BissellThere is currently significant interest in the industry towards computer-aided history-matching methods. These methods must lead to a good match of production data, but also satisfy a priori geological constraints. The "pilot-point method" appears to provide a promising solution to the problem, by combining geostatistical techniques with gradient-based optimisation algorithms. In this paper, the optimal choice of location and number of pilot-points is addressed. A new approach is presented, which combines two criteria. The first criterion is sensitivity: pilotpoint locations must be such that a change in pilot-point parameters significantly influences the objective function. The other criterion is uncertainty: if pilot-point values are to be changed in the history-matching process, they must be subject to a high degree of uncertainty. Combining the kriging variance and the results of an eigenvalue/eigenvector analysis of the Gauss-Newton matrix - which is calculated for a regular subset of gridcells - allows a rational choice to be made about the best number and positions for the pilot-points. The performance of the suggested method is evaluated by applying it to a synthetic case study consisting of 5 layers, 3000 gridcells and 6 wells. Matched production data include Well Pressures, Water Cuts and Gas-Oil Ratios. The multiple solutions obtained are used to quantify the uncertainty on production forecasts.
-
-
-
Solution to Boundary Value Problem Relevant in Upscaling
More LessThree boundary value problems for Laplace's equation related to 2D Darcy flow through a gap in barrier are considered. Solutions to two of the problems are obtained, and an exact formula for the effective permeability represented by a gap in an infinitely thin barrier is found. Deriving the effective penneability represented by a gap in a barrier with positive thickness is more difficult, and the problem is here reduced to the task of determining the period matrix of a hyperelliptic Riemann surface of genus three from the knowledge of the periods of a certain analytic differential on the surface.
-
-
-
The Impact of Flow Regime on the Upscaling of Heterogeneous Reservoirs
Authors C. Coll, A. H. Muggeridge and X. D. JingOil recovery and water breakthrough time for a waterflood are a function of the prevailing flow regime and the reservoir heterogeneity.
-
-
-
Steady-State Upscaling
Authors S. Ekrann and J. O. AasenSteady-state upscaling is based on steady-state solutions to the two-phase flow equations. We study features of steady-state solutions, and the applicability of upscaled flow functions based thereon in transient situations. Also, efficient computation of steady-state solutions is addressed: The existence of a class of problems is proved, where two-phase streamlines (in the viscous limit) are identical to streamlines in the corresponding one-phase problem.
-
-
-
Upscaling Two-Phase Flow Through Double Porosity Media
By M. PanfilovA new theoretical tooI is proposed to solve the problem of scale-up flow in highly heterogeneous media, where the permeabilities of dense blocks and high conductive matrix are contrast. The practical goal was to develop some regular procedure to pass from a fine geological grid to a coarse numerical grid in reservoir simulation.
-
-
-
Steady-State Scale-Up Models
Authors G. E. Pickup and K. D. StephenThe calculation of pseudo relative permeabilities using fine-scale simulations is time consuming. However, if we can assume that a system is close to a steady-state, this process can be speeded up considerably. Frequently, the capillary equilibrium limit is assumed at small scales (30 cm or less), when the flood rate is low. At high flow rates and larger distance scales, capillary pressure effects may be negligible, and we may use a viscous-dominated steady-state method which assumes constant fractional flow. Steady-state pseudos may also be calculated at intermediate flow rates using fine scale simulations, and allowing the flood to come into equilibrium at different fractional flow levels.
-
-
-
Handling Multiple Realizations in a Long-Term Production Forecast
More LessA hydrocarbon bearing formation represents a classic example of a system where uncertainty is incorporated into the reservoir data, Quality and quantity of data at early stages of field evaluation and development planning is not sufficient for an adequate application of statistical analysis. Uncertainty in reservoir characterization makes an overall estimation of resources and reserves more subjective and, therefore, less reliable. Attempts to handle uncertainties by conventional methods (for example, by running multiple realizations, sensitivity analysis, etc.) in a scattered environment require considerable resources.
-
-
-
Determining Relative Permeabilities by Use of Experimental Design for Very Heterogeneous Samples
Authors B. Ferreol, B. Corre and M. RedenzIt is usually assumed when measuring relative permeabilities that the reservoir sample is homogeneous. Great progress has been made in non destructive techniques to quantitatively estimate the degree of homogeneity of the core samples: CT scan, surface minipermeameter and mini-sonic, miscible displacement, ... These methods are nowadays routinely used to scan the samples prior to any measurement and to select the most appropriate one in terms of petrophysical properties and homogeneity. Unfortunately, core samples are often heterogeneous either because it was not possible to select a more homogeneous sample or because the heterogeneity is intrinsic to the facies. A lot of attention has been paid to that question in the recent years, and the possible impact of heterogeneities at the small scale on relative permeabilities is well documented in the literature¹.
-
-
-
Geostatistical Modelling of Fluid Flow on Flexible Grids
More LessPaper was made available at the Conference
-
-
-
Contrained Kriging and Simulation of a Well Layering Towards a Geophysical Thickness Map
Authors A. Haas, P. Biver and K. AltisenIn this paper, a simple (but theoretically consistent) formulation is presented to constrain kriging or simulation of individual thicknesses (observed at well locations) to a global thickness map issued from geophysical measurements. The method consists of a correction applied to the non constrained results ; this correction takes into account the uncertainties on the individual layers (kriging variances) and the uncertainty on the global layer (uncertainty on geophysical measurements). First, the theoretical background of the technique is described briefly; the relationship with the full cokriging system is depicted. Subsequently, the method is applied to a practical industrial field case. From encouraging results, some advice are derived to use this new algorithm correctly. Finally conclusions are drawn conceming the advantages and the limitations of these correction formula. Further research is suggested to treat more complex geometries.
-