Changes

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

The economic success of any prospect ultimately depends on reservoir system performance. The reservoir system controls two critical economic elements of a prospect: (1) the rate and (2) the amount of hydrocarbons recovered. In geologic terms, [[Classifying pore systems|pore type]] and [[pore-fluid interaction]] are the most important elements determining reservoir system performance.The interrelationship of reservoir [[porosity]], [[permeability]], thickness, and lateral distribution determines reservoir system quality. Although quality prediction is most effective with large amounts of superior data, useful predictions can still be made from very limited data. This section discusses methods for predicting the quality of sandstone and carbonate reservoir systems.

The economic success of any prospect ultimately depends on reservoir system performance. The reservoir system controls two critical economic elements of a prospect: (1) the rate and (2) the amount of [[hydrocarbon]]s recovered. In geologic terms, [[Classifying pore systems|pore type]] and [[pore-fluid interaction]] are the most important elements determining reservoir system performance.The interrelationship of reservoir [[porosity]], [[permeability]], thickness, and lateral distribution determines reservoir system quality. Although quality prediction is most effective with large amounts of superior data, useful predictions can still be made from very limited data. This section discusses methods for predicting the quality of sandstone and carbonate reservoir systems.

==Sandstones vs. carbonates==

==Sandstones vs. carbonates==

Sandstones and carbonates are the dominant reservoir rocks. Although quite similar, they are different. The table below<ref name=ch09r10>Choquette, P., W., Pray, L., C., 1970, [http://archives.datapages.com/data/bulletns/1968-70/data/pg/0054/0002/0200/0207.htm Geologic nomenclature and classification of porosity in sedimentary carbonates]: AAPG Bulletin, vol. 54, no. 2, p. 207–250. Classic reference for basic concepts regarding carbonate porosity.</ref> compares variables affecting reservoir system quality for sandstones vs. carbonates.

[[Sandstone]]s and [[carbonate]]s are the dominant [[reservoir]] rocks. Although quite similar, they are different. The table below<ref name=ch09r10>Choquette, P., W., Pray, L., C., 1970, [http://archives.datapages.com/data/bulletns/1968-70/data/pg/0054/0002/0200/0207.htm Geologic nomenclature and classification of porosity in sedimentary carbonates]: AAPG Bulletin, vol. 54, no. 2, p. 207–250. Classic reference for basic concepts regarding carbonate porosity.</ref> compares variables affecting reservoir system quality for sandstones vs. carbonates.

{| class = "wikitable"

{| class = "wikitable"

|-

|-

| Sediment composition

| Sediment composition

| High variability (depending on provenance and depositional environment)

| High variability (depending on [[provenance]] and [[Depositional environments|depositional environment]])

| Low variability [variations of CaCO₃ and MgCa(CO₃ )₂ ]

| Low variability [variations of [[limestone]] and [[dolomite]] ]

|-

|-

| Cement mineralogy

| Cement mineralogy

| Quartz, calcite, dolomite, clay, and anhydrite, etc.

| [[Quartz]], [[calcite]], [[dolomite]], [[clay]], and [[anhydrite]], etc.

| Aragonite, high- and low-Mg calcite, dolomite

| [[Aragonite]], high- and low-Mg calcite, dolomite

|-

|-

| Original pore geometry

| Original [[Pore systems|pore geometry]]

| Intergranular

| Intergranular

| Intergranular predominates, but intragranular is important

| Intergranular predominates, but intragranular is important

| Intergranular = intercrystalline = moldic > microporosity

| Intergranular = intercrystalline = moldic > microporosity

|-

|-

| Uniformity of pore size, shape, and distribution

| Uniformity of [[Pore and pore throat sizes|pore size]], shape, and distribution

| Fairly uniform within a facies

| Fairly uniform within a facies

| Ranges from fairly uniform to extremely heterogeneous, even within a facies

| Ranges from fairly uniform to extremely heterogeneous, even within a facies

|-

|-

| Influence of diagenesis

| Influence of [[diagenesis]]

| Minor to major

| Minor to major

| Usually major

| Usually major