What is dolomitization explain the process of dolomitization?
dolomitization, process by which limestone is altered into dolomite; when limestone comes into contact with magnesium-rich water, the mineral dolomite, calcium and magnesium carbonate, CaMg(CO3)2, replaces the calcite (calcium carbonate, CaCO3) in the rock, volume for volume.
How does dolomitization happen?
Dolomitization is a geological process by which the carbonate mineral dolomite is formed when magnesium ions replace calcium ions in another carbonate mineral, calcite. It is common for this mineral alteration into dolomite to take place due to evaporation of water in the sabkhas area.
What is the diagenesis process?
diagenesis, sum of all processes, chiefly chemical, by which changes in a sediment are brought about after its deposition but before its final lithification (conversion to rock). An example of diagenesis is the chemical alteration of a feldspar to form a distinctly new mineral in its place, a clay mineral.
What is dolomitization porosity?
The dolomitization is a process that dolomite precipitates accompanied by calcite or aragonite dissolution. Therefore, the porosity evolution is ultimately controlled by the difference in rates between dissolution and precipitation (Landes, 1946).
How does dolomitization increase porosity?
The porosity of the rock is not only affected by the 13% volume shrinkage on mole-for-mole dolomitization, but it also depends on the amount of compaction which takes place. Replacement of the remaining mud will then lead to a marked increase in permeability and may also result in a porosity increase.
Where does dolomitization take place?
limestone
Dolomitization occurs in nature or even in untied limestone deposit or in already solid limestone rocks. Dolomites that occur in the untied deposit are called early diagenetic or sin-sedimentary. It also forms by dolomitization of limestone as late-diagenetic or postsedimentary events.
Where does dolomitization occur?
Dolomite occurs by suppression of aragonite or calcite, i.e. dolomitization process. Dolomitization occurs in nature or even in untied limestone deposit or in already solid limestone rocks. Dolomites that occur in the untied deposit are called early diagenetic or sin-sedimentary.
What is a diagenetic environment?
Specifically, diagenesis “is the cumulative physical, chemical and biological environment; these processes will modify an organic object’s original chemical and/or structural properties and will govern its ultimate fate, in terms of preservation or destruction”.
Does dolomitization increase porosity?
If a lime mud is dolomitized, the mud will be compacted as the dolomite crystals grow, resulting in a decrease in porosity. Replacement of the remaining mud will then lead to a marked increase in permeability and may also result in a porosity increase.
What happens to the reservoir quality when carbonate rocks are Dolomitised?
Dolomitization is a reaction that involves a volume decrease, i.e., the volume of minerals is reduced with the conversion of calcite to dolomite, so that the number of pores within the reservoir increases [13,23].
When does dolomitization and pressure solution occur in diagenesis?
Our understanding of deep subsurface diagenesis is incomplete, but we do know that dolomitization, pore-fill cementation and pressure solution occur at depth and may be extremely important. During uplift, fracturing, additional cementation and leaching may occur.
How does dolomitization change the properties of a rock?
Dolomitization is a diagenetic process that converts limestones to dolostones through a microchemical process of calcium carbonate dissolution and dolomite precipitation. Dolomitization can change the rock fabric and the petrophysical properties significantly because the dolomite crystals are commonly larger than the replaced limestone particles.
How long does it take for dolomitization to occur?
Dolomitization in the zone of mixed marine and freshwater begins in early diagenetic phase and the deposition lasts for a few hundred thousand years (>200,000 years), as the process is very slow. The mixed zone of seawater and freshwater, during an extensive period of time, moves simultaneously with the lowering or rising of sea level.
How does dolomitization of aragonite and calcite occur?
Dolomite occurs by suppression of aragonite or calcite, i.e. dolomitization process. Dolomitization occurs in nature or even in untied limestone deposit or in already solid limestone rocks.