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Fault seal analysis for reservoir development (view source)
Revision as of 21:13, 28 September 2021
, 21:13, 28 September 2021no edit summary
Fault Seal Analysis method has key factors that are vertical movement (throw) and shale or clay content (Vshale) in the rocks involved in faulting<ref name=Yieldingetal_1997>Yielding, G., B. Freeman, and D. T. Needham, 1997, Quantitative fault seal prediction: AAPG Bulletin, v. 81, no. 6, p. 897-917.</ref>. One method of quantity is the Shale Gouge Ratio (SGR) and Hydrocarbon Column Height (HCH) which will analyze fault characteristics ([[:file:GumelarFigure2.jpg|Figure 2]]).
Fault Seal Analysis method has key factors that are vertical movement (throw) and shale or clay content (Vshale) in the rocks involved in faulting<ref name=Yieldingetal_1997>Yielding, G., B. Freeman, and D. T. Needham, 1997, Quantitative fault seal prediction: AAPG Bulletin, v. 81, no. 6, p. 897-917.</ref>. One method of quantity is the Shale Gouge Ratio (SGR) and Hydrocarbon Column Height (HCH) which will analyze fault characteristics ([[:file:GumelarFigure2.jpg|Figure 2]]).
==Juxtaposition analysis==
One of the mechanisms of the process of hydrocarbon insufficiency is juxtaposition. This barrier is caused by the presence of rocks that have different physical properties of rocks, namely permeability and porosity. Rocks that have greater permeability and porosity will not flow hydrocarbons in the direction of smaller permeability and porosity. If the sandstone is in contact with the claystone then a juxtaposition seal is possible because the physical parameters of the claystone do not allow fluid to pass through the rock.
[[file:GumelarFigure3.jpg|thumb|300px|{{figure number|3}}Illustration of three factors that influence fault analysis: juxtaposition seal, fault rock seal and fault reactivation<ref name=Yieldingetal_2010>Yielding, G., P. Bretan, and B. Freeman, 2010, Fault seal calibration: A brief review: Geological Society London Special Publication 347, p. 243-255.</ref>.]]
The first order of seal analysis cannot be separated from identifying the juxtaposition of the reservoir in all fracture planes by using layers of interpretation results that have been defined on the fracture plane<ref name=Yieldingetal_2010 />. It is seen in [[:file:GumelarFigure3.jpg|Figure 3]] that in several ways that hydrocarbon fluids can escape. In the top illustration, there is a juxtaposition seal, which means that there is a barrier which is a concern for rocks with low permeability and reservoir. The middle illustration shows that sand to sand juxtaposition which can occur due to the nature of relatively similar permeability. The bottom illustration shows the reactivation of a fault, so that it can become a hydrocarbon migration pathway. Because faults can form porosity which results in the opening of a new fault plane.
==Allan diagram==
Allan<ref name=Allan_1989>Allan, U. S. 1989, Model for hydrocarbon migration and entrapment within faulted structures: AAPG Bulletin, v. 73, p. 803–811.</ref> developed a graphic technique to map the relative position of the lithology cut-offs on both the footwall and the hanging-wall. This methodology is often called Allan Mapping. Using this approach, cross-fault spill points and hydrocarbon flow path potential can be determined from the lithological alignment (juxtaposition), based on the assumption that the fault itself does not have sealing properties and that it is not an open channel for flow. Allan's mapping relies on the construction of the fault surface section ([[:file:GumelarFigure4.jpg|Figure 4]]) which is defined as the appearance of the stratigraphic geometry that touches across the fault by removing the hanging-wall<ref name=Allan_1989 />. The representation of a part of the fault surface is often a vertical or planar surface. The lithology of the footwall and hanging-wall fault blocks is projected onto the surface portion of the fault and is used to determine where the reservoir lithology of one fault block is juxtaposed with the non-reservoir lithology of the opposite fault block.