Fluid migration pathways

Preferred fluid migration pathways are influenced by porosity and permeability, sedimentary sequences, facies architecture, and fractures. Porosity is a measure of pore space per unit volume of rock or sediment and can be divided into two types absolute porosity and effective porosity. Absolute porosity (n) is the total void space per unit volume and is defined as the percentage of the bulk volume that is not solid material. The equation for basic porosity is listed below ... 

Fracturing and fault compartmentalization of sandstones fundamentally affects reservoir properties and may significantly influence the fluid migration pathways in a basin (Knipe, 1993). Open fractures may form high-permeability conduits, whereas cement-sealed fractures form barriers to fluid flow. Seismic, petrophysical and reservoir performance data allow regional (field-scale) effects of faulting on fluid flow to be constrained. However, much fracturing and associated cementation may occur at sub-... 

Funayama, M. Manor, J. S. 1995. Pore water salinity as a tool for evaluating reservoir continuity and fluid migration pathways in the Wilcox Group of Central Louisiana. Transactions of the Gulf Coast Association of Geological Societies, 45 195-201. 

Makarov, V.K. and L.J. Morozov, 1980. Hydrodynamic barriers in petroliferous basins of North Africa. International Geology Review, Vol. 22, no. 11, pp. 1286-1290 Mann, D.M. and A.S. Mackenzie, 1990. Prediction of pore fluid pressures in sedimentary basins. Marine and Petroleum Geology, 7, pp. 55-65 Mann, U., 1989. Revealing hydrocarbon migration pathways. Geologische Rundschau 78/1, pp. 337-348... 

Figure 9. Conceptual diagram of the important paleohydrologic controls on the occurrence and distribution of MVT mineralization, and arsenic enrichment. This figure is simplified from one originally constructed by T. Hayes (written communication, 1989). Sandstone is. shown as a dot pattern, limestone as a rectangular pattern, dolomite as a trapezoidal pattern, and shale as the dash-dot pattern. The arrows show pathways of fluid migration, and the letters show the locations of ore formation discussed in the text.

These case studies revealed that (i) active migration pathway of fluids can be imaged by 2-D/3-D effective stress maps using seismic velocity data, and (ii) the predicted pore pressures at the well using both seismic and sonic data are in agreement with each other and with an independent set of data the RFT measurements. 

Oil and gas field waters have long been used in diagenetic studies, primarily as vehicles for understanding basin fluid flow, oil migration pathways, evolution of water composition, and reservoir com-partmentalization. However, water samples used for these purposes must be original formation water, not mixed with drilling mud or with injected fluids such as fracture fluid, waterflood water, or other fluids used for enhanced oil recovery (EOR),... 

McCartney et al. analysed a very significant data set of formation water composition and formation pressure data to determine whether regional barriers to fluid flow affect formation water compositions, evolution of overpressure distribution and changing hydrocarbon migration pathways through time. They suggest the Jurassic and Triassic aquifers of the Central North Sea have essentially behaved as a large composite aquifer, which has many implications for the deep prospectivity of the CNS. 

In real porous media, mineral deposition or dissolution would create preferential pathways to solute migration by diffusion and by advective fluid flow. Simulation of the formation of preferential pathways is beyond the capabilities of the present, one-dimensional model. Future development will extend the present model to higher dimensionality in order to examine these interesting processes. 

Chemoattractants induce release of arachidonic acid from phospholipids in PMNL [244] and the arachidonate metabolism is stimulated in a manner similar to that of ionophore A23187 [235,245], Inhibitors of arachidonate metabolism inhibit leukocyte migration [246-248], However, with inhibition mainly of the cyclooxygenase pathway, an increase of PMNL migration is observed in vitro [ 150,247,249] and in vivo [6,250,251], Formation of LTB and 5-HETE is significantly increased in synovial fluid in rheumatoid arthritis [40], These data support the concept that an endogenous lipoxygenase product is involved in the PMNL chemotactic response. 

---