Sedimentary Process in Petroleum Geology

Sedimentary Process 

Sedimentary Rocks is a rocks that is composed of particles of preexisting rocks that have been weathering , transported, deposited and lithified. The important process that leads to creation of the rocks includes weathering, erosion and transportation, deposition, then burrial and then lithification.

1. Weathering 

Weathering is the breakdown of solid rocks, It is a natural process of insitu mechanical disintegration and or chemical decomposition of rocks exposed on the surface of the earth. When the influence of contain physical and chemical agencies of the atmosphere.

The different types of rock weathering are mechanical , chemical and biological, Most resistance in terms of chemical is quartz and least resistance is feldspar.

2. Transportation

Transportation is how sediment move out of the source (Site of weathering) to site of deposition. The different transporting agent are running water, wind, and Ice in the form of glacier.

Different methods of transportation are - 1. Bed load transportation 2. Saltation 3. Suspension and 4. Solution

3. Deposition 

When the transporting agent loose their ability  to carry due to diminished velocity deposition environment are sites at which sediment rest. For example :- Pluvial (River) environment , delta , beach marine environment etc.

4. Burrial and Lithification 

Once sediment have been deposited they must be burried and lithified to become rocks. Each new layer of sediments burries the one beneath ( A little bit deeper ), the weight of overlying sediment would pressure on the sediments would pressure on the sediments and the temp of sediments increase slowly, Lithification is the opposite of weathering. It is the many processes that together to take loss sediments  and make it stick together, as a rock. This process is also called consolidation, during this processes many physical and  chemical changes take place within the sediment, such changes are called diagnesis. 

Diagnesis includes the following two processes.

1. Compaction by Overline Sediment

Involving the lose packing of the individual grains by eliminating the pore spaces.

2. Cementation 

Development of secondary minerals in the formation pore spaces which can blinds the sediment particles together. This material may be introduces from the process of groundwater or derived from solution.

Notes:- Data is collected from university notes and person experiences, Main purpose of this articles is to help peoples.

Articles Written by

Ritu Raj Medhi

Founder & President

Chief Technical & Editorial Officers

Petroleumbuddy Websites and Initiatives 

ASP Flooding in Enhance Oil Recovery (EOR) || Petroleum Engineering

ASP Flooding Characteristics & Overview

ASP flooding is a Chemical Enhanced Oil Recovery method where Alkali, Surfactant and Polymers are injected either in a given sequence or all together. The three chemicals have different effects. Often they interact with reservoir fluids (oil & water), rock minerals and among themselves to enhance oil recovery. In this article, we will explore these effects.

Effects of Alkali:

Alkali such as Caustic Soda (Na2CO3) are added to the chemical cocktail. It has two primary impact:-

• Alkali reacts with the in-situ "Petro-Acids" and produces "Soap", a kind of surfactant. It compliments the surfactant requirement.
• Alkali competes for the absorption sites along with polymer and surfactant.
• Alkali causes 'emulsification' which improves sweep efficiency.
• Oil Entrainment Effect.
• Bubble Entrapment Effect
• Wettability Reserval.

Effects of Surfactant:

Surfactant primarily works and IFT reducer. It loosen up the oil particles attached to the rock surfaces and thus assist move them closer to  the producing well. The effect is usually quantified using "Capillary Number", defined by:

          Nc = uμ / σ

where,
          u = displacing fluid velocity
          μ = displacing fluid viscosity
          σ = Inter-Facial Tension (IFT)

As Capillary No. increases, more oil droplets get detached from the rock surfaces and move towards the producers. In other words, it reduces the Irreducible Water Saturation (S_wirr).

Effect of Polymer:

 Polymer helps in improving the sweep efficiency of the injected chemical by mobility control.  Due to "ViscoElastic" property, polymer flooding helps push/pull oil droplets from dead-end pores.  Another, often ignored positive impact is the favorable economics compared to water injection. For the same effect, less amount of pore volume need to be injected.

The Synergies and Interactions of ASP:-

 When the three types of chemicals, namely Alkali, Surfactant and Polymer are injected "together", an increased oil recovery is observed. It is probably due to the advantage obtained

 due to the synergies and interactions between the said chemicals. These effects can be summarized as follows:

1.   1. Alkali competes with absorption sites and hence reduces polymer and surfactant absorption, hence their requirements.

2. Alkali reacts with acidic crude oil and generate soap, called "petro-soap". This soap has low optimum salinity whereas injected synthetic surfactant has higher optimum salinity. As a result, the mixture of petro-soap and synthetic surfactant has a wider range of optimum salinity where IFT is low.

3. Emulsion improves sweep efficiency as the small bubble blocks the wider pore throats and forces the displacing fluid to enter the narrower pore throats. Petro-soap and surfactant make emulsion stable due to reduced IFT. Polymer may also help to stabilize emulsions owning to its high viscosity to reduced coalescence.

4. Addition of polymer improves sweep efficiency of the entire chemical slug, enabling more oil bearing zone exposed to surfactant and alkali.

       

       Notes:- Data is collected from different university notes book, e&p company websites and persons experiences. Main purpose of this articles help to oil and gas industry peoples and students. 

       Articles written by:-

       Bhaskarjyoti Khanikar

      Guest Writter 

      Dibrugarh University

   

        

High Sophisticated Measuring instrument for improving Enhanced Oil Recovery (EOR) || Petroleum Engineering

ATTENTION THETA FLEX HIGH PRESSURE CHAMBER (EOR) -

As demand of oil continue to rise all across the world, the traditional primary and secondary extraction methods are no longer productive in producing oil. To extract these oils, EOR techniques aims to improve oil mobility through lowering interfacial

tension, lowering oil viscosity and reducing wettability of oil on reservoir surfaces . Understanding how EOR approaches alter interfacial tension and wettability is important, and these properties are heavily dependent on temperature and pressure . It is crucial to have the ability to measure these properties at temperatures and pressures relevant to reservoir conditions.

With the Attension Theta Flex High Pressure Chamber, contact angle and interfacial tension measurements are made easy and intuitive right in the lab. With market-leading sample sizes, automatic pressurization capability, unique chamber design, easy sample loading and cleaning, the Attension Theta Flex High Pressure will advance EOR research.

The Attension Theta High Pressure is a tensiometer for measuring wettability and interfacial tension at high pressures and high temperatures within enhanced oil recovery research. With the harsh conditions of an oil reservoir in mind, the instrument is designed to ensure ease of use and yet offer wide measurement possibilities. Attension Theta High-Pressure Unique Piston functions are:-

1. Measure surfactants or corrosive liquids.
2. Increase pressure without adding fluid into the measurement cell.
3. Enables constant surfactant concentration over different pressures.
4. Smart design to avoid pump corrosion from brine and other corrosive bulk solutions.
5. Sample Port for easy introduction and cleaning.
6. Automatic Pump Option.

Notes:- Data is collected from different university notes, E&P company references  and author experiences. Main purpose of this article to help students and industry related peoples.

Article Written by -

Bhaskarjyoti Khanikar

Guest Writter

Dibrugarh University