Reservoir Architecture Model Research Articles

Reservoir architecture model and heat transfer modes in the El Tatio-La Torta geothermal system, Central Andes of northern Chile

In this work, we present an update for the conceptual model of the El Tatio-La Torta geothermal system, one of the most studied geothermal fields in the Central Andes of South America. Using the structural model reported by Veloso et al. (2019) for northern Chile, the conceptual model proposes a reservoir architecture and heat transfer modes at different scales, connecting the distal catchment area located 15 km east of El Tatio with the outflow of the system: El Tatio geothermal field. The main results of this work are (a) the location of a complex and large reservoir system below El Tatio and La Torta, composed by three main levels named A, B and C, which are connected by the intersection of NW-striking left-lateral and N-striking thrust faults, (b) an explanation for the upflow below La Torta, which is given by the tectono-geothermal environment of the geothermal system, (c) the possible location of the main catchment area at the Tocorpuri basin/caldera, located 15–20 km to the east from the El Tatio geysers, and (d) an explanation for the apparent hydraulic disconnection at El Tatio observed by pressure interference tests, which is coherent with the proposed structural setting for the geothermal field. These results give a physical representation about the fluid circulation and heat transfer modes, connecting La Torta and El Tatio as a unique large-scale geothermal system in the Central Andes.

Paleogeomorphic Influence on Facies Characteristics of Braided Delta and Reservoir Prediction—An Example from L oilfield in Bohai Bay Basin

Five wells of L oilfield in Bohai bay basin have drilled 10 - 15 meters thick oil layer in the Paleogene delta. Due to the deep-buried reservoir and the poor seismic performance, it is difficult to identify the reservoir genesis, and predict reservoir distribution. By analyzing core, well logging and seismic data, a stable mudstone section is selected as the correlation marker to establish a stratigraphic framework. The paleogeomorphology is reconstructed after decompaction correction and paleobathymetric analysis. Based on the differences of paleotopography and sedimentary facies, the study area mainly develops two delta systems: low gradient coarse-grain delta system and steep gradient delta-turbidite system. The favorable reservoir of low gradient coarse-grain delta, which is thick and has good lateral connectivity, mainly locates in the delta front. The favorable reservoir of steep gradient delta-turbidite system locates in the delta front and turbidite facies, and the delta front deposits are thin and have poor lateral connectivity. The boundary of delta front is first depicted on the basis of paleotopography. In combination with reservoir architecture and forward modeling analysis, the seismic attribute is then optimized to predict the distribution of favorable reservoir. Using this method, several sets of oil-bearing sandbodies have been drilled in L oilfield, and the prediction accuracy of reservoir distribution is proved to be high. This study demonstrates that the paleogeomorphology plays an important role in controlling the genesis and distribution of the delta reservoir and provides reference for the reservoir prediction in similar oilfields.

Reservoir architecture model of the Nieuwerkerk Formation (Early Cretaceous, West Netherlands Basin): diachronous development of sand-prone fluvial deposits

Abstract The sand-prone fluvial Delft Sandstone Member of the Nieuwerkerk Formation is the main target for geothermal exploitation in the West Netherlands Basin. Uncertainty reduction in the modelling of permeability heterogeneity and connectivity of the sandstone reservoir units is of prime importance in the low-profit geothermal energy market. Lithostratigraphic correlation of the Delft Sandstone Member dates back to the 1970s, and considers the fluvial deposits as Valanginian (140–134 Ma) in age and synchronously deposited throughout the basin. Analysis of newly-acquired palynological data, in combination with well-log correlation and seismic interpretation, enabled the construction of a sequence-stratigraphic framework for the Nieuwerkerk Formation, in which the fluvial sandstones were deposited in a much wider age range than previously believed, from Late Ryazanian to Valanginian (142–134 Ma). The depocentre of fluvial deposition shifted in time from NE to SW across the width of the basin. This diachronous development resulted in a discontinuous spatial arrangement of fluvial sandstones. The new reservoir architecture model will aid in the well placement of geothermal doublets and the assessment of interference risk of adjacent geothermal projects.

Research on meandering river reservoir deposition architecture and 3D modeling of the Gudao Oil field in the Bohai Bay Basin

The distribution of remaining oil is controlled by internal sand body heterogeneity in the middle and late stages of oil field development. Reservoir architecture analysis has been conducted in the third sand group in the Guantao Formation of the Gudao Oil field. Different scales of reservoir architecture units have been identified, including complex meandering river belt, single meandering river belt, single point bar and inner point bar. Four different single channel signatures have been found in the research area to identify the single channel belt. The single point bar has been distinguished based on point bar development characteristics. The architecture of the inner point bar has been analyzed based on subsurface well data and empirical formulas. The lateral accretion angle of the muddy layer ranges from 5° to 8°, the interspace between lateral accretion muddy layers ranges from 20 to 35 m, and the horizontal width of a single lateral accretion sand body is 55–120 m. Based on the above-mentioned reservoir architecture analysis, a reservoir architecture model has been established using the hierarchical modeling method. A three-dimensional porosity and permeability model has been developed within architecture model constraints and could provide a reliable geological template for oil field development and production.

Distribution of remaining oil based on fine 3-D geological modelling and numerical reservoir simulation: a case of the northern block in Xingshugang Oilfield, China

As the Xingshugang Oilfield is in the late stage of development, a conventional geological model could not meet the needs of further enhancing oil recovery, and the establishment of a fine 3-D geological model, namely the 3-D reservoir architecture model, is urgently required. The 3-D reservoir architecture model has a strong advantage in the detailed characterization of the distribution of various architectural elements and flow baffles and barriers in 3-D space. Based on the abundant data from close well spacing, in combination with the understanding of sedimentary facies and reservoir architecture, this study builds the 3-D reservoir architecture model to show the spatial distribution of different architectural elements and intercalations (mud drapes) under the control of third-, fourth- and fifth-order bounding surfaces. The study then establishes the property model under the control of sedimentary facies (architectural elements). Subsequently, based on the fine 3-D geological model, the distribution of remaining oil is obtained after the numerical reservoir simulation. The remaining oil primarily lies in the port of channel bifurcation, the parts blocked by intercalations and abandoned channels, and the edges of different facies. This observation provides a theoretical basis for further development and adjustment.

Three-dimensional reservoir architecture modeling by geostatistical techniques in BD block, Jinhu depression, northern Jiangsu Basin, China

To reduce or avoid some of the ambiguities in a heterogeneous reservoir, a fine three-dimensional model would be inevitably established with the application of geostatistical techniques. BD oilfield is a low-permeability fractured reservoir with many fracture types, which composes a multi-azimuthal fracture system, causing strong anisotropy and heterogeneity. Moreover, fracture provides not only accumulation space for oil and gas but also channels for migration of hydrocarbons and water dashing and thus plays a leading role in controlling BD reservoir production. With the continuous exploitation of oil in reservoir for more than 30 years, BD oilfield has currently stepped into high water cut stage, exposing many problems such as low oil recovery, poor exploitation stability, rapid oil production decline, and one-way water intrusion. Therefore, a detailed reservoir characterization, constructed to describe reservoir behavior under strong water drive in a well-developed fractured reservoir, is urgently needed. In this study, combined with three-dimensional geostatistical techniques, an accurate and efficient reservoir parameter model that occurs in a strong heterogeneous fractured reservoir has been constructed through stratigraphic correlation and sedimentary facies analysis. Hence, all the study presented above will be available for well location, remaining oil potential-tapping and oil recovery improvement during the later study work.

Hierarchical nested simulation approach in reservoir architecture modeling

Abstract A hierarchal nested reservoir architecture simulation methodology is proposed to meet the current challenges in reservoir heterogeneity modeling. It matches the architecture geological research principle which is shortened as “hierarchical constraint, pattern fitting and multi-dimension proof”. In this proposed methodology, different modeling approaches are adopted in different stages of architecture analysis, and the result from current architecture analysis is used as constraints and information for next level architecture analysis. The meandering river reservoir architecture modeling is used to illustrate the proposed methodology. The meandering river sand complex is the first modeling stage. The Fluvsim program is updated to characterize the bounding surface of single channel within the channel sand complex. In second stage, a new point bar simulation program, Barsim, is developed. The abandoned channel and the known point bars are assembled together according to the quantity fluvial reservoir architecture model. The spatial vector based program Ihssim is developed to characterize the inclined heterogeneity strata (IHS) inside the point bar sand at third level architecture study stage. Through such an integrated three modeling procedures, the heterogeneity characteristics of a reservoir which is represented by reservoir architecture elements in different scales and hierarchical levels are presented in the final reservoir model.

Application of Truncated Gaussian Simulation Algorithm in Alluvial Fan Reservoir Architecture Modeling

This article counted the distribution regularity and the spread pattern of each tertiary architecture through detailed study of alluvial fan reservoir architecture of the sealing core drilling well in the Karamay group which under the sixth middle area of Karamay oilfield. The tertiary architecture of middle-fan subfacies are: braided channel, sheetfloot microfacies and gritfloot microfacies. Truncated Gaussian simulation algorithm can be used to simulate the middle-fan subfacies of alluvial fan for they have an obvious zone law. Described the distribution regularity and spread pattern of middle-fan subfacies architecture effectively. Figured out the contact relationship among different architectural units preferably. It has a certain reference for other oilfields with the same type reservoir of architecture modeling.

Connectivity of fluvial point-bar deposits: An example from the Miocene Huesca fluvial fan, Ebro Basin, Spain

The Huesca fluvial fan (Miocene, Ebro Basin, Spain) contains a low-gradient, mixed-load fluvial system. A detailed outcrop study of its meandering river deposits shows that the preservation of elongate channel-floor sandstone ribbons is common and that these deposits create a continuous along-stream sand-to-sand connectivity between successive crescent-shaped sandy point-bar accumulations on both sides of the channel. The combined appearance of the sandstone resembles a string of beads consisting of a thin, sinuous ribbon with thick and wide protuberances on either side. The studied meandering river sandstone bodies are laterally amalgamated and vertically stacked with a net-to-gross (N/G) ratio of about 40%. They occur in 1–1.5-km (0.62–1-mi)-wide, northeast–southwest-oriented elongate meander belts occupying paleochannels. Beyond these belts, the sandstone is limited to isolated bodies with a very low N/G ratio. A generic model of the string-of-beads geometry, based on the outcrop data analysis, showed a significant increase of bulk rock volume for the connected string of beads compared with the model of isolated point bars. The outcrop results demonstrate the potential for channel-floor sandstone bodies to be preserved in a low-gradient, mixed-load fluvial system and their importance in connecting point-bar units in an along-stream direction. We recommend that fluvial reservoir architecture modeling programs include a function that allows the connectivity between channel-floor and point-bar architectural elements. This may greatly impact the estimated reservoir volumes and recovery factors in primary and secondary production as well as influence the sweep efficiency of enhanced recovery technologies. Marinus E. Donselaar received his M.Sc. degree in geology from the University of Utrecht and his Doctor of Science degree in reservoir geology from Delft University of Technology, both in the Netherlands. He worked at the Comparative Sedimentology Division at the University of Utrecht. Since 1987, he has been a lecturer in sedimentology at Delft University of Technology. His research interests are in the modeling of fluvial and barrier island reservoir architecture. Irina Overeem has a Ph.D. from the Faculty of Civil Engineering and Geosciences, Delft University of Technology, Netherlands, where she was an assistant professor in geological modeling from 2005 to 2007. Her research focuses on the numerical modeling of fluviodeltaic processes. Over the last six years she has held a position at Institute of Arctic and Alpine Research (INSTAAR), and she is presently working at the Community Surface Dynamics Modeling Facility at the University of Colorado.