Topic
Effective porosity
About: Effective porosity is a research topic. Over the lifetime, 1199 publications have been published within this topic receiving 26511 citations.
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TL;DR: In this paper, effective porosity, saturated sonic velocity and saturated uniaxial compressive strength were determined on a large number of Borrowdale Volcanic Group volcaniclastic core samples from three boreholes at Sellafield, Cumbria.
Abstract: The effective porosity, saturated sonic velocity and saturated uniaxial compressive strength were determined on a large number of Borrowdale Volcanic Group volcaniclastic core samples from three boreholes at Sellafield, Cumbria. The work formed part of the UK Nirex Limited site investigation into whether the Sellafield area could be suitable as a repository for intermediate and low level radioactive waste. Most of the intact samples were of low to very low effective porosity, had a high sonic velocity and were very strong to extremely strong. However, a proportion of values deviated significantly from this. Bivariate analysis showed a negative relationship exists between sonic velocity and effective porosity. The cross plots of these two parameters with uniaxial compressive strength showed a wide range of strength values for samples of low effective porosity and high sonic velocity. Six failure types were identified during the uniaxial compressive strength tests. The strongest samples tended to fail through the matrix and the weakest rock samples tended to fail through haematized material or along haematized veins. Effective porosity and sonic velocity measurements could not distinguish between those samples that failed through the matrix and those that failed along discrete narrow veins. The presence of narrow haematized veins has a major effect on the intact rock strength.
82 citations
Book•
01 Jan 1988
TL;DR: In this paper, the authors present a model for gas reservoir engineering based on the K-value method and a flow-after-flow test. But they do not consider the effect of gas injection on the phase behavior.
Abstract: 1. Introduction. Natural gas. Gas reservoir engineering. Objective and organization. Units and symbols. 2. Reservoir properties. Introduction. Rock types. Porosity. Viscous flow resistance. Inertial flow resistance. Rock compressibility. Capillary pressure. Relative permeability. 3. Gas properties. Introduction. Composition. Phase behaviour. Real-gas law. Z-factor. Compressibility. Condensate/gas ratio. Formation-volume factor. Viscosity. 4. Phase behaviour. Introduction. K-value method. Equation-of-state method. Laboratory experiments. Multistage separation. 5. Recoverable reserves. Introduction. Bulk volume. Pore volume. Hydrocarbon pore volume. Gas and condensate initially-in-place. Recoverable reserves. Uncertainty. 6. Material balance. Introduction. Wet-gas reservoirs. Gas-condensate reservoirs. Non-volumetric depletion. Aquifer influx. 7. Single-phase gas flow. Introduction. Steady-state Darcy flow. Steady-state radial flow. Non-Darcy flow. Transient flow. Linear flow - constant terminal rate. Linear flow - constant terminal pressure. Radial flow - Constant terminal rate. Non-radial flow. 8. Gaswell testing. Introduction. Backpressure equations. Flow-after-flow tests. Isochronal and modified isochronal tests. Transient well-pressure equations. Drawdown tests. Buildup tests. Multiple-rate transient tests. Example of multiple-rate transient test analysis. 9. Wellbore flow mechanics. Introduction. Single-phase flow equations. Pressure distribution in shut-in wells. Rate-dependent pressure losses. Pressure distribution in producing wells. Multi-phase flow. Minimum unloading rate. 10. Water coning. Introduction. Dupuit critical production rate. Schols critical production rate. Cone breakthrough. Water/gas ratio. 11. Natural depletion. Introduction. Development chronology. Reservoir performance. Well-inflow performance. Tubing-flow performance. Well deliverability. Depletion simulator. 12. Gas injection. Introduction. Injection-well performance. Microscopic mixing. Viscous fingering. Gravity overlay. Stratification. Well Pattern. Pattern-flood model. Appendices. Units and conversion factors. Physical and mathematical constants. Physical properties natural-gas components. Author index. Subject index.
80 citations
TL;DR: In this paper, the porosity distribution of a single ionic species in a low permeability clay medium was investigated at the millimeter-scale using multiscale data, and the results showed that porosity distributions are mainly controlled by surface interactions and pore-constriction electrochemical controls.
80 citations
TL;DR: In this article, the authors use point-counting categories that clearly distinguish between grains and intergranular materials to calculate porosity loss from modal analyses of thin sections, which is a useful technique for characterizing diagenesis and porosity evolution of sandstone reservoirs.
Abstract: Calculation of compactional porosity loss from modal analyses of thin sections is a useful technique for characterizing the diagenesis and porosity evolution of sandstone reservoirs. To obtain meaningful results, however, it is essential to assume an appropriate value for the "original porosity" and to use point-counting categories that clearly distinguish between grains and intergranular materials. Because of the latter requirement, it is commonly not appropriate to make calculations of compactional porosity loss from modal analyses that were not performed for the specific objective of measuring intergranular volume. Suites of modal analyses from deeply buried sandstone units typically show wide variations in the relative importance of compaction versus quartz cementation. This heter geneity must reflect subtle variations in depositional sand characteristics, in particular the distribution of detrital intergranular clays that tend to promote both mechanical grain rearrangement and stylolitic grain dissolution, as well as locally inhibiting quartz cement growth. Despite wide variation in the mechanism of porosity loss, total (helium) porosity tends to be relatively constant at individual well locations, suggesting a close interdependence between compaction and quartz cementation, with total porosity loss dependent mainly upon thermal exposure (either maximum temperature or time-temperature integral).
79 citations
TL;DR: In this article, a 12-year experience of the North Sea chalks and the data from > 180 wells was used to establish and test on the other fields in the area and is described in this paper.
78 citations