Updated Rock Type Definition and Pore Type Classification of a Carbonate Buildup, Tengiz Field, Republic of Kazakhstan

Skalinski, Mark; Kenter, J.A.M.; Jenkins, Steve; Tankersley, Terrell

doi:10.2118/139986-ms

Cited by 11 publications

(7 citation statements)

References 6 publications

(4 reference statements)

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“…These are interpreted as forth-or fifth-order parasequences . Figure 5 shows the variations in depositional rock type, spectral gamma ray (SCR, spectral gamma ray, detects potassium, thorium and uranium, THOR, thorium %), porosity (PHIE, effective porosity) and bitumen % by volume (Skalinski et al 2009). Core photographs from representative wells from each study unit are presented as Figures 6 and 7.…”

Section: Resultsmentioning

confidence: 99%

Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan

Dickson¹,

Kenter²

2014

Journal of Sedimentary Research

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Predicting the diagenetic modification of reservoir quality in carbonate fields is poorly understood but of paramount importance to reservoir characterization. The diagenetic processes and current pore system are reported for two parasequences from the platform center to the margin of the Tengiz reservoir (, 16 km); the late Visean (Lvis13 cbs 900) and Bashkirian (Bash2.5 MSF 350) parasequences are separated by 8 million years.Syndepositional fibrous cement (. 10% rock volume) and aragonite skeletal molds developed in both parasequences. On subaerial exposure, brown soil-related calcite, and meniscus and pendant cements were emplaced in both parasequences.The application of CL petrography to these rocks for the first time has revealed the depositional components and early marine components are altered developing a mottled pattern implying that their original chemistry is not preserved. The principal calcite cement shows a complex growth pattern by CL that is unreported from any other calcite cement. CL is also used to divide the main cement into stage 1, nonluminescent, and stage 2, orange to brown luminescent, calcite. Stage 1 calcite shows vadose meniscus and pendant fabrics followed by uniform phreatic euhedral terminations. Stage 1 cement is patchily distributed at a millimeter scale; 28% to 40% in the Visean and 0.5% to 22% in Bashkirian grainstones. Stage 1 cement is more abundant at the center of the platform in the late Visean than at its margin. Abundant stage 1 calcite creates a framework that prevents later compaction preserving a high porosity at the center of the platform. This sweet spot is reinforced by the deposition of late-stage bitumen cement that occupies 8% rock volume at the margin of the platform but is almost absent at its center. Stage 1 d 13 C values (22.4% to +1.7%) are derived by dissolution of host rock, and their d 18 O values (26.3% to 23.7%) are compatible with precipitation from meteoric or mixed marine-meteoric water.Depositional micrite and micritic grains are transformed by dissolution-precipitation processes into porous microrhombic calcite not by Ostwald ripening. Microrhombic calcite is ubiquitous in the Tengiz icehouse, dispelling the myth that this fabric is restricted to greenhouse epochs.At , 300 million years before significant burial the study grainstones were patchily cemented and dissolved to reach peak porosity; their transformed texture set up flow paths that controlled the distribution of later diagenetic products. Reservoir compartmentalization did not occur through extensive hardground formation at this time as occurs in some greenhouse sequences, but ash bands at parasequence boundaries were turned into tonsteins and wackestones were compacted perhaps sufficiently to influence vertical flow.CL examination of stage 2 calcite that adds 0.5% to 16% to rock volume reveals that its precipitation was episodic and switched sites as the pore network became blocked through precipitation and compaction and was opened by new fractures. A change from acute to equant habit ...

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Section: Resultsmentioning

confidence: 99%

Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan

Dickson¹,

Kenter²

2014

Journal of Sedimentary Research

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“…Allen et al, 2001;Frank et al, 2005;Skalinski et al, 2009) the richness of the NMR signal is both its strength and its weakness since it remains very difficult to determine and calculate precisely all the parameters listed previously for exploration in carbonates. Indeed, many effects such as pore coupling (e.g.…”

Section: Introductionmentioning

confidence: 99%

NMR relaxation of neritic carbonates: An integrated petrophysical and petrographical approach

Vincent¹,

Fleury²,

Santerre³

et al. 2011

Journal of Applied Geophysics

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“…The introduction of PRTs that resemble statistically meaningful groups (or "bins") of continuous reservoir properties emphasizes the need for very careful calibration or "tuning" of those PRTs with observed geological control, diagenetic versus depositional or, as probably in most cases, a "hybrid". The PRT definition and workflow for the Tengiz Unit 1 reservoir was published by Skalinski et al (2009). In this paper we will limit the PRT descriptions to emphasize their link with the hybrid depositional-diagenetic control and associated spatial patterns and trends used for the modeling.…”

Section: Methodsmentioning

confidence: 99%

“…Diagenetic products of the transformation of the metastable mineralogy of carbonates have been the focus of many studies since the mid-fifties but relatively little is understood of the actual rock-fluid processes and associated spatial patterns and trends (Jones and Xiao, 2006). Similarly, carbonate pore systems (pore type and pore throat distributions) are complex and workflows for the prediction of such pore systems from wire line-logs are lagging behind that for siliciclastics (Skalinski et al, 2009). In reservoirs with a high data density capturing the existing heterogeneity by classic geostatistical estimation techniques may be sufficient, however, in reservoirs that lack such data density (for example Tengiz) other techniques should be deployed.…”

Section: Static Modeling Of Carbonate Reservoirsmentioning

confidence: 99%

“…The introduction of petrophysical rock types (PRTs) at Tengiz has contributed to improved estimates of volumes of oil in place and improved reservoir management. PRTs are the category of rocks which are characterized by specific ranges of petrophysical properties; exhibit distinct relationships relevant for flow characterization, are identified by logging surveys, and are linked to geological attributes like primary texture or diagenetic modifications (Skalinski et al, 2009). It must be noted, however, that additional information from production logs and dynamic tests are required to reliably predict transport properties in the simulation model.…”

Section: Petrophysical Rock Types and Reservoir Quality Prt Definitionmentioning

confidence: 99%

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Tengiz Field (Republic of Kazakhstan) Unit 1 Platform Static Model: Using a Hybrid Depositional – Diagenetic Approach

Kenter

Tankersley²,

Skalinski

et al. 2010

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Traditional rock typing combined with an inferred depositional linkage for variogram-based simulation is a standard approach in carbonates. In the Tengiz Unit 1 platform, reservoir properties of carbonates as defined by Petrophysical Rock Types (PRTs) are the product of primary depositional facies and diagenetic modification that have separate spatial trends and interactions. Careful, multidisciplinary and targeted analysis is required to unravel such trends from the usually complex hard data sets, but is critical as an understanding of the trends forms the basis for reservoir modeling of the Tengiz Unit 1 platform. Depositional cycles in the Unit 1 Tengiz platform (Late Visean to Bashkirian) are made up of a succession of generally shoaling lithofacies overlying a sharp base with evidence for subaerial exposure and/or flooding. Systematic study of the diagenetic products of several sequences across the platform using petrography, stable isotopes and CL revealed that the diagenetic modification includes early meteoric dissolution and subsequent cementation, late burial dissolution and late burial bitumen cementation.. PRTs are designed to include spatial attributes of the combined stratigraphic, facies and diagenetic framework form the basis for the Multiple Point Statistics and Facies Distribution Modeling (MPS/FDM) simulation of the SIM08T Unit 1 static platform reservoir model. Of the six PRTs, one is linked to volcanic ash (PRT 1), one associated with bitumen (PRT 2) and four with increasing porosity (PRTs 3-6) where PRT 3 tight and PRTs 4-6 represent increasing reservoir quality with PRT 6 the highest quality. PRT maps and a vertical proportion curve were used to generate the facies probability cube and convolved with training images, specifying the spatial interrelationship, to generate a PRT realization. The revised sequence stratigraphic framework and integration of novel concepts in modeling the diagenetic overprint addressed the need for a refined understanding of the platform in preparation for the FGP miscible gas injection project. In addition, the extensive use of MPS/FDM modeling approaches in Unit 1 has resulted in a more realistic integration of both depositional and diagenetic trends in the Unit 1 platform.

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Updated Rock Type Definition and Pore Type Classification of a Carbonate Buildup, Tengiz Field, Republic of Kazakhstan

Cited by 11 publications

References 6 publications

Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan

Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan

NMR relaxation of neritic carbonates: An integrated petrophysical and petrographical approach

Tengiz Field (Republic of Kazakhstan) Unit 1 Platform Static Model: Using a Hybrid Depositional – Diagenetic Approach

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