Diagenetic Mechanisms of Porosity and Permeability Reduction and Enhancement

1994 ◽  
pp. 59-118 ◽  
Author(s):  
Michael D. Wilson ◽  
Peter T. Stanton
Keyword(s):  
Permeability Reduction ◽  
Porosity And Permeability

scholarly journals Permeability Changes Resulting from Quartz Precipitation and Dissolution around Upper Crustal Intrusions

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Samuel W. Scott ◽  
Thomas Driesner
Keyword(s):  
Host Rock ◽  
Permeability Reduction ◽  
Rock Permeability ◽  
Permeability Changes ◽  
Order Of Magnitude ◽  
Porosity And Permeability ◽  
Fluid Convection ◽  
Flow Heat ◽  
Primary Porosity ◽  
Host Rocks

It has long been recognized that quartz precipitation from circulating hydrothermal fluids may reduce porosity and permeability near intrusions. However, the magnitude of permeability changes and potential feedbacks between flow, heat transfer, and quartz precipitation/dissolution remain largely unquantified. Here, we present numerical simulations of fluid convection around upper crustal intrusions which explicitly incorporate the feedback between quartz solubility and rock permeability. As groundwater is heated to ~350°C, silica dissolves from the host rock, increasing porosity and permeability. Further heating to supercritical conditions leads to intensive quartz precipitation and consequent permeability reduction. The initial host rock permeability and porosity are found to be main controls on the magnitude and timescales of permeability changes. While the permeability changes induced by quartz precipitation are moderate in host rocks with a primary porosity ≥ 0.05, quartz precipitation may reduce rock permeability by more than an order of magnitude in host rocks with a primary porosity of 0.025. Zones of quartz precipitation transiently change locations as the intrusion cools, thereby limiting the clogging effect, except for host rocks with low initial porosity. This permeability reduction occurs in timescales of hundreds of years in host rocks with initial high permeability and thousands of years in host rocks with intermediate permeability.

TEMPERATURE CONTROLLED POROSITY/PERMEABILITY REDUCTION, FLUID MIGRATION, AND PETROLEUM EXPLORATION IN SEDIMENTARY BASINS

1998 ◽  
Vol 38 (1) ◽  
pp. 453 ◽  
Author(s):  
P.A. Bjorkum ◽  
P.H. Nadeau
Keyword(s):  
Fluid Pressure ◽  
Sedimentary Basins ◽  
Petroleum Exploration ◽  
Fluid Migration ◽  
Permeability Reduction ◽  
Permeable Sediments ◽  
Basin Scale ◽  
Thermally Driven ◽  
Fracture Fluid ◽  
Porosity And Permeability

Findings mainly from the Norwegian Continental Shelf indicate that at temperatures greater than approximately 60°C, internally sourced quartz cementation and diagenetic clay become important porosity and permeability reduction factors, respectively. Porosity loss due to quartz cementation in sandstones and siltstones proceeds mainly independent of effective stress or fluid pressure. Porosity loss rates approach those required to generate high fluid overpressures at approximately 120°C, which can result in hydrofracturing of the overlying low permeability shales. In thick low permeable sediment sequences, the probability of km scale vertical fluid migration increases. These thermally driven processes are capable of generating and sustaining fluid overpressure and facilitate fluid migration for up to tens of millions of years. Unlike mechanical compaction models, this model predicts that porosity loss and therefore fluid migration will continue despite the buildup of overpressure, even during periods of no sedimentation. In sealed compartments, fluid flow from more deeply buried high permeable lithologies will occur by hydrofracturing of overlying low permeable lithologies, preferentially along near vertical faults if present. When hydrofractures are induced from high permeable sediments, they will propagate vertically through overlying low permeable sediments, unless they enter lithologies with sufficient permeability and volume to bleed off the fracture fluid propagation pressure. Quantitative analysis of the mineral reactions causing porosity loss cannot only identify sediments in thermal zones which are expelling fluids, but also lithologies in thermal zones which are likely to receive those fluids, in addition to the timing and rates of fluid migration. The model has important applications for evaluating petroleum exploration risks and the potential for remigrated hydrocarbon plays both at basin scale and prospect level.

Overpressure Identification Using The Eaton Method on The Gumai Formation of Geragai Graben, Jambi Sub Basin

2020 ◽  
Author(s):  
A. O. Marnila
Keyword(s):  
Pressure Data ◽  
Stratigraphic Sequence ◽  
Fine Grained ◽  
Marine Sedimentation ◽  
Plot Analysis ◽  
Significant Reversal ◽  
Porosity And Permeability ◽  
Upper Level ◽  
Type Data ◽  
Fine Grained Sand

Geragai graben is located in the South Sumatera Basin. It was formed by mega sequence tectonic process with various stratigraphic sequence from land and marine sedimentation. One of the overpressure indication zones in the Geragai graben is in the Gumai Formation, where the sedimentation is dominated by fine grained sand and shale with low porosity and permeability. The aim of the study is to localize the overpressure zone and to analyze the overpressure mechanism on the Gumai Formation. The Eaton method was used to determine pore pressure value using wireline log data, pressure data (RFT/FIT), and well report. The significant reversal of sonic and porosity log is indicating an overpressure presence. The cross-plot analysis of velocity vs density and fluid type data from well reports were used to analyze the causes of overpressure in the Gumai Formation. The overpressure in Gumai Formation of Geragai graben is divided into two zones, they are in the upper level and lower level of the Gumai Formation. Low overpressure have occurred in the Upper Gumai Formation and mild overpressure on the Lower Gumai Formation. Based on the analyzed data, it could be predicted, that the overpressure mechanism in the Upper Gumai Formation might have been caused by a hydrocarbon buoyancy, whereas in the Lower Gumai Formation, might have been caused by disequilibrium compaction as a result of massive shale sequence.

THE BASIC TYPES OF SECONDARY CHANGES IN RESERVOIR ROCKS IN THE TERRITORY OF THE WEST SIBERIA PLATE

2015 ◽  
pp. 26-30
Author(s):  
A. V. Podnebesnykh ◽  
S. V. Kuznetsov ◽  
V. P. Ovchinnikov
Keyword(s):  
Oil Recovery ◽  
West Siberia ◽  
Recovery Factor ◽  
Change Processes ◽  
The West ◽  
Reservoir Rocks ◽  
Tectonically Active ◽  
Porosity And Permeability ◽  
Active Zones ◽  
Regional Character

On the example of the group of fields in the West Siberia North the basic types of secondary changes in reservoir rocks are reviewed. Some of the most common types of such changes in the West Siberian plate territory include the processes of zeolitization, carbonation and leaching. These processes have, as a rule, a regional character of distribution and are confined to the tectonically active zones of the earth's crust. Due to formation of different mineral paragenesises the secondary processes differently affect the reservoir rocks porosity and permeability: thus, zeolitization and carbonization promote to reducing the porosity and permeability and leaching improvement. All this, ultimately leads to a change of the oil recovery factor and hydrocarbons production levels. Study and taking into account of the reservoir rocks secondary change processes can considerably influence on placement of operating well stock and on planning of geological and technological actions.

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