Porosity loss

Mackenzie PD, Horney DP, Sivavec TM. Mineral precipitation and porosity losses in granular iron columns. J Hazard Mater 1999 68 1-17. 

Chuhan F. A., Kjeldstad A., Bjprlykke K., and Hpeg K. (2000b) Porosity loss in sand by grain crushing—experimental evidence and relevance to reservoir quality. Mar. Petrol. Geol. 19, 39-53. 

Lundegard P. D. (1992) Sandstone porosity loss—a big picture view of the importance of compaction. J. Sedim. Petrol. 62, 250-260. 

Walderhaug O. (1996) Kinetic modeling of quartz cementation and porosity loss in deeply buried sandstone reservoirs. Am. Assoc. Petrol. Geologists Bull. 80, 731-745. 

F is expelled compaction driven flux (mVm per s), A0r is the porosity reduction during time T (s) and H is the true vertical thickness of rock column undergoing compaction (m). In the calculation of fluxes over the Melke-Gam Formation border we have assumed a subsidence rate of 2.0 x 10 km/year (sedimentation rate = 0.5 mm/year Fig. 2). The porosity of the Melke Formation at about 4 km depth is 3.0% (Table 3). The porosity loss due to compaction is es-... 

This confirms that the main mechanism of porosity loss in the quartz-rich samples (quartz cementation) is less detrimental to permeability than... 

Fig. 11. (A) Plot of intergranular vol% versus cement% for arenites with less than 10% of matrix (see Houseknecht, 1987). (B) Plot of compactional porosity loss (COPL) versus cementation porosity loss (CEPL) for arenites with less than 10% cf matrix (see Lundegard, 1992).

In thin sections from the oil zone, we observe that calcite II is associated with oil staining. On the other hand, in the water zone type III calcite shows no association with oil. Below the water-oil contact, in zones where there is no or only scarce calcite cement development, mechanical and chemical compaction was the main diagenetic process responsible for porosity loss. 

In order to better evaluate the effects of compaction on porosity loss, the packing proximity index (Kahn, 1956) was measured in 44 samples derived from both oil and water zones in the Albacora Field. Plotting these data against calcite cement volumes (Fig. 17) indicates that for the same calcite cement content, the packing proximity index is lower in oil zone samples than in samples derived from the water zone. This means that compaction was less intensive in the oil zone than in the water zone. Furthermore, there is a relatively good correlation... 

Porosity reduction due to recementation af ter the dissolution event is generally small (1-2%) and involved kaolinite, quartz, pyrite and ferroan cal-cite and dolomite cements. Locally, as much as 10% of late cements have been precipitated. Kaolinite usually reaches no more than trace amounts, although locally up to 6% has been observed. Late quartz overgrowths are negligible. Late pyrite generally does not exceed 1% however, locally it may occlude all available pore space. Late ferroan calcite cement has completely filled the available pores at a few levels, but the total porosity loss by this cement and by late ferroan dolomite is not significant. 

The history of porosity development at the various reservoir levels in Hibernia Field clearly underscores the role of carbonate cements in delaying irreversible porosity loss in sandstone reservoirs. Early non-ferroan and ferroan calcite cements, precipitated at burial depths shallower than 2000 m, are widespread in oilfields around the world (e.g. Lindquist, 1977 Blatt, 1979 Loucks etal., 1984 Olaussen et a/., 1984 Bjorlykke et a/., 1986 Imam Shaw, 1987 Kantorowicz et al., 1987 Saigal Bjorlykke, 1987 and many others) and are typical as first major cements for a group of cement parageneses (Franks Forester, 1984). Four different sources of this early calcite cement have been considered in the literature (i) carbonate dissolu-... 

Paxton, S. T., Szabo, J. O., Ajdukiewicz, J. M. Klimentidis, R. E. 2002. Construction of an intergranular volume compaction curve for evaluating and predicting compaction and porosity loss in rigid-grain sandstone reservoirs. American ciation of Petroleum Geologists Bulletin, 86, 2047-2067. 

Sandstone porosity loss versus depth in Haltenbanken is similar to trends seen for the North Sea, especially between 1.4 and 2.6 km (Bjorlykke et al. 1989). This could suggest that overpressure does not influence the porosity depth trends in these basins. It is possible, accordingly, that the lack of correlation between overpressure and shale porosity reported at Haltenbanken by Hermanrud et al. (1998) is a manifestation of disequilibrium in the sense that the shales did not have time to respond chemically to the overpressure development. This suggests that mechanical models for compaction cannot adequately explain porosity loss in deep shales and that a time/temperature... 

When the rate of quartz cementation becomes significant at temperatures exceeding 80-100°C, the porosity loss is mainly due to quartz cementation. Calculations show that the advective transport of silica in the pore water can be ignored as the low flow rates due to compaction are so low and because of the low solubility and solubility gradients of silica. The rate of import or export of silica is a function of the water flux (F), the solubility of quartz as a function of temperature (at) and the geothermal gradient (VT)... 

When the diagenesis is isochemical at a scale of 1-lOm, the compaction and shortening (AZ) of a sedimentary sequence (Z) is equal to the porosity loss (A tp ) due to quartz cementation. The reduction in stratigraphic thickness is defined by ... 

In the previous section, a mechanistic model was used to describe the compaction of the porous aggregate. To check its validity, we compare our model with existing experimental measurements (Elias and Hajash, 1992), and examine effects in porosity-loss due to applied stresses, temperatures, and grain sizes. 

Mackenzie, R D. Homey, D. R Sivavec, T. M. (1999) Mineral Precipitation and Porosity Losses in Granular Iron Columns. J. Hazardous Materials 68, 1-17. 

Primary migration presents a different problem Shales are impermeable and normally provide excellent seals that inhibit upward petroleum movement (see later). How then can petroleum emigrate from an impermeable source bed into a permeable carrier formation It is not enough to invoke simple compaction of clay during burial. When clays compact, most of the porosity is lost in the first kilometer or so of burial. Temperatures are still too low to permit kerogen maturation. At the depths at which petroleum generally forms (some 3 to 4 km) little porosity loss takes place. 

Newton, G.H. Chen, S.L.. and Kramlich, J.C., Role of porosity loss in limiting sulfur dioxide capture by calcium-based sorbents, AIChE J., 35(6), 988-994 (1989). 

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