Free Oil and Gas Reservoir Characteristics Essay Sample

This research paper will briefly examine deltaic and estuarine oil exploitation methods. The paper at first examines the characteristics of the deltaic and estuarine oil reservoirs after which their implication of oil exploitation in the two reservoirs are examined. A reservoir has been defines as a, "subsurface volume of porous and permeable rock that has both storage capacity and the ability to allow fluids to flow through it" (Halliburton 24).

Deltaic oil reservoirs

According to Mcllroy (2004), ancient deltas have been identified to be quite significant due to vast amount of oil they harbor. In order for oil to be exploited from such reservoirs it will be significant if its characteristics are noted. Mcllroy (2004) gives the characteristics as follows:

I. These reservoirs consist of an amalgamation of several different sandstones which includes mouth bars and distributary channels which result into the formation of multilateral and multistory systems. Another characteristic about the deltaic reservoirs is they form similar upward-coarsening and shallowing successions.

According to scribd (2010) the following are other characteristics:

I. The topsets have sand and silt which is cut through with stream channel deposits and contains terrestrial fossils

II. The foresets consists of the silt and clay which slope seaward and may contain some marine fossils.

III. The bottomsets consists of clay and horizontal beds in which marine fossils dominate.

The geological facies is as follows:

I. The lithology: Siliciclastic deposits; Glauconite presence; Coal bed; Limestone and evaporates; presence and Medium sand to clay grain size.

II. Sedimentary structure: the surface is erosional; presence of cross and massive bedding and bioturbations.

These make the deltaic reservoirs to be generally possessing porosities of up to 35 percent.

Estuarine Oil Reservoirs

Estuaries are similar to deltas and the estuarine oil reservoirs are similar in characteristics with the delta oil reservoirs. According to Sergio et al., (2002), generally estuarine reservoirs are characterized by high hydrocarbon accumulations. They argue that these reservoirs are highly heterogeneous due to the presence of complex sub-tidal and inter tidal estuarine channels. The reservoirs are also characterized with shoreface deposits (Sergio et al., 2002).

Implication for (oil and gas) production in deltaic and estuarine environment

Basically the implications which befall oil production in deltaic environment are same as those in the estuarine environment bearing in mind that these are literary the same environment in "oil production sense."

The first implication which obvious comes to light is the conflict with human activities. Nin most cases estuaries and deltas good fishing ground and extraction of oil from these will possibly make not possible to be carried out. Extraction of oil from these regions also another risk of sea contamination in case an accident occurs which leads to leaking of oil. Being at the entrance to the sea will make oil leaking a quite serious if such an accident takes place. Extracting oil from the estuarine and deltaic environment will inevitable change the environment affecting aquatic and land life.

On the light side such extraction of oil will make a positive contribution to the oil reserves and help to meet the demand for gas which on rising with each day.

It should be noted that studies are being carried pout through simulation experiments on extraction of gas from these environments. The Niger delta petroleum system is an example of oil extraction taking place on a delta (Michelle et al., 1999).

 

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