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Vol. 3 (2000 year), No. 1
Madatov A.G., Sereda A.-V.I.
The forward and inverse fluid dynamic problems of pore pressure prediction in sedimentary basins. 1. The theoretical aspect
In the paper the numerical solutions of the forward and inverse fluid dynamic problems for geological time scale have been considered in connection to excess pore pressure (EPP) prediction. The set of the most sensitive to the EPP evolution model parameters has been introduced. The forward problem of the fluid dynamics describes the compaction, HC-saturation and overpressure evolution vs. time and depth. The corresponding real well data set is used as an input for the inversion routine. The 1.5D reduction of the 3D inverse problem is developed. Such approach allows to achieve a more unique and stable inverse problem solution in reasonable computing time. The particular forward modelings for a homogeneous and layered medium are discussed. Applications of the approach to the EPP prediction are demonstrated on the practical examples.
(in Russian, стр.26, fig. 17, tables. 1, ref 29, MS Word 95, MS Word 95 2410 Kb)
Vol. 3 (2000 year), No. 2
Madatov A.G., Sereda A.-V.I.
The forward and inverse fluid dynamic problems of pore pressure prediction in sedimentary basins. 2. The practical aspect
The new method of the pore pressure prediction based on calibration of the basin model has been introduced. The theory of relevant forward and inverse problems solution was given in part one of the work published before in this issue. The review of the present day practice used for pore pressure prediction includes classical approaches (drill engineering) as well as modern approaches (basin modelling). The intrinsic non-uniqueness and noise stability of these methods have been analysed. The proper position of the new method among the existing one is determining. The concept has been illustrated by the practice example from the different sedimentary basins in the world (the Timano-Petchora oil and gas province, the North Sea, the Gulf of Mexico deep water). A description of the functionality of the relevant computer technology PANDAВ® has been given. The new technology capacities have been illustrated by the example of the quantitative pore pressure prediction before and during drilling (North Sea).
(in Russian, стр.16, fig. 15, tables. 1, ref 33, MS Word 95, MS Word 95 464 Kb)
Vol. 4 (2001 year), No. 1
Madatov A.G., Sereda V.-A.I.
The decomposition of 3-d overpressure evolution model in basin scale and its application to the fault seal analysis
A new 3-D fluid dynamics model of multilayered media has been developed, with complex burial history and capable for calibration. This new method extends the 1.5-D approach to the solution of forward and inverse problems for excess formation pressure evolution at the basin scale, earlier proposed by the authors. The concept of a laterally conductive reservoir carrier among massive permeable rocks has been introduced. The system of sealing faults has been considered as pressure barriers in the relevant lateral drainage system. The vertical and lateral directions of pore fluid migration have been accounted recursively in two relevant mass conservation models. It allows building of an effective numerical scheme capable of modelling formation pressure compartmentalization and calibrating the sealing properties of surrounding faults. We introduce as a goal of calibration the set of independent fault attributes sensitive to the seal properties and sufficient to describe the lateral barrier. A software program package based on this approach has been developed, and some results of its practical application for fault analysis in the North Sea basin have been discussed.
(in English, стр.18, fig. 13, tables. 2, ref 33, MS Word 95, MS Word 95 232 Kb)
Vol. 6 (2003 year), No. 1
Madatov A.G. and Sereda V.-A.I.
Upscaling of a basin model required for pore pressure prediction before and during drilling
A new approach to the basin model upscaling for drilling applications has been described. The approach is based on the composite 3D model of the fluid dynamics in basin time scale. The system analysis and inversion theory have been involved. The work flow of consequent data and model processing has been considering phase by phase. The consequence starts at the 3D seismic data cube where the potential basin model could have M*106 cells to be specified and finishes at the upscaled Earth model given on N*102 cells of optimised non-regular grid. The routine is designated to keep prediction quality at given level at any stage of upscaling. The final Earth model is fully prepared for real time calibration of relevant Earth model and pore pressure prediction / updating of prediction while drilling. The details of the model description and non-local sensitivity analysis have been given in two appendices.
(in Russian, стр.26, fig. 7, tables. 1, ref 35, MS Word 95, MS Word 95 940 Kb)
Vol. 8 (2005 year), No. 1
Madatov A.G., Sereda A.-V.I.
The effective basin model concept and fast 3-D overpressure modelling in basin time scale
The approaches and background Earth model applicable for overpressure phenomenon investigation have been reviewed and systemised in the context of their applicability for pre-drill and while-drill prediction. An Effective Basin Model (EBM) concept has been introduced basing on the successive assumption simplifying full-scale basin modelling solutions. The EBM concept allows to incorporate 1-D and 2-D approaches to overpressure modelling in basin time scale. The relevant combine 3-D overpressure modelling operator has been designed. The operator has been capable to account for the main overpressuring mechanisms including 3-D pressure communication phenomena (centroid effect, dipping aquifer beds, pressure drop across the sealing faults, etc.). A stable implicit scheme has been developed for numerical pressure solutions. The scheme reveals absolute numerical stability within the practically important range of model parameters and combined grid properties. The benefits of the developed combined 3-D HD approach versus full scale 3-D regular grid solution in computing speed is estimated to be about NЧ(105-106) times for the Earth model cube based on about 109 cells. The applicability of the new fast 3-D modelling scheme has been tested on real geology settings and has been checked against real data. The Gulf of Mexico basin has been used for prototyping of the centroid effect on salt induced positive Cainozoic structures. The North Sea tectonics has been used for simulating overpressured fault sealed compartments.
(in English, стр.39, fig. 17, tables. 1, ref 113, Adobe PDF, Adobe PDF 2500 Kb)
Vol. 8 (2005 year), No. 1
Madatov A.G., Sereda A.-V.I.
A multi-well data inversion purpose-built for calibration of an effective basin model at overpressure prediction
The calibration of a basin scale hydro-dynamic model based on a multi-well data set has been introduced as an ill-posed inversion problem. Global and local optimisation strategies have been reviewed in this connection. In terms of the conditionally unique definition according to Tikhonov this problem is getting a range of locally unique e-equivalent solutions. All of them are a potentially resolve calibration problem. It is shown that for the multi-well case the relevant inverse problem solution can be arranged with additional criteria, which provide globalisation and lead to the area unique solution of the calibration problem. The approach, strategy and computation algorithm have been developed. The approach implies inverting of porosity - pore pressure data sets attached to the calibration well positions within the range of established and upscaled in the advance effective basin model. The numerical implementation has been checked on theoretical and real data examples. It reveals acceptable converging speed at practically justified data quality stop criterion. The application of the developed algorithm and numerical scheme for the 12-wells real data example (the North Sea) has been discussed in details.
(in English, стр.40, fig. 21, tables. 3, ref 88, Adobe PDF, Adobe PDF 1400 Kb)
Vol. 8 (2005 year), No. 1
The seismic velocity analysis in reflection wave method has been traditionally applied for the pre-drill prediction of overpressured subsurface formations since the early 1960s. The location of the first successful implementations was the Gulf of Mexico, where thick Pleistocene-Miocene sediments are represented by clastic rock, which are poorly consolidated at the upper part of the section and are often overpressured from the very top. Despite of long implementation history this application of the seismic method remains to be questionable in other sedimentary basins especially those where exploration targets are associated with Mesozoic and older interval of the sections. Here velocity based prediction of over-hydrostatic pressured formations becomes hazardous and uncertain operation. The main reasons of these facts are: low sensitivity of the velocity derived overpressure response inherent for consolidated clastic and carbonate rocks; essentially 1-D mechanical compaction non-adequate model of multi-mechanism overpressure phenomenon; natural limitation in seismic wave spatial resolution; non-purposely oriented seismic data processing, where compressional/shear wave velocity is not treatable as a rock property. The majority of published about this topic reviews were focused on last two problems trying to find the best solution on the way of purpose-built processing strategy and perfecting seismic data inversion approaches. This paper reviews theoretical velocity models applicable for description of a target phenomenon in connection with results of ultra-sonic lab measurements and empirical relationships established for seismic frequency band. The error free (direct) overpressure response potentially detectable from velocity data is analysed on this ground for different depth intervals of the section. The sand, shale and carbonate lithologies are distinguished. The relevant normalised anomaly is estimating for speculative and real case examples. The combining of basin scale models of deposystem evolution with full waveform inversion approach is suggested as a proper way for developing the relevant multi-disciplinary strategy of overpressure prediction.
(in English, стр.36, fig. 19, tables. 1, ref 155, Adobe PDF, Adobe PDF 1600 Kb)
Vol. 9 (2006 year), No. 3
Madatov A.G., Sereda A.-V.I.
The pre-drill and real time while drilling overpressure prediction based on Effective Basin Model concept
The problem of the pre-drill predictability of an overpressure phenomenon has been considered within the range of the Effective Basin Model concept. The inherent and numerical origins of the relevant prediction scenarios have been analysed. The solutions of numerical problems are attached in the form of the appendixes. The approach to the stabilisation of an inherent prediction error has been proposed. The real time correction of a pre-drill prediction in during drilling ("Look Ahead") mode has been considered in the context of the re-calibration or/and adjustment of a prediction model and a framework earth model respectively. The re-calibration problem has been introduced as an extension of the single-well data inversion problem. The corresponding ill-posed task has been formulated and the approach to getting its locally unique solution has been discussed. The relevant computer algorithm has been described in details. The applicability of the new approach and solution to the real time drilling conditions have been tested based on the speculative (North Sea area) and real data (Gulf of Mexico) examples. These tests confirm high converging speed of the updating routine and flexibility of the algorithm. The achieved results correspond to higher accuracy in comparison with available standard methods.
(in English, стр.28, fig. 8, tables. 3, ref 52, Adobe PDF, Adobe PDF 1610 Kb)
Vol. 13 (2010 year), No. 3
The paper analyzes the problems and constraints for the development of civil society in contemporary Russia, forms of interaction between institutions of the modern Russian state and the emerging civil society institutions, and perspectives of solving these problems.
(in English, стр.38, fig. 25, tables. 2, ref 112, Adobe PDF, Adobe PDF 0 Kb)
Vol. 13 (2010 year), No. 3
An effective reservoir model concept has been introduced to ensure a practical solution to the history matching problem for a multi-well data set. A deterministic process-based approach to its architecture and specification has been implemented. The common hydraulic element concept is combined with generalized empirically grounded permeability functions for mixed clastic lithology to get a 3D grid containing a reservoir transport property. The clay content constant is used as a universally sensitive control model parameter for specification of absolute and relative permeability distribution for both laterally continuous and discontinuous cases. The power trend functions are used for approximation of inherent lateral distribution of clay content in field scale. Being in close relation with relevant depositional environment they are considered as 'soft' model constraints. The relative sensitivity of model vector components is analyzed based on plausible multi-well model examples.
(in English, стр.8, fig. 19, tables. 3, ref 108, Adobe PDF, Adobe PDF 0 Kb)