Enhancement Petrophysical Properties of Carbonate Reservoirs Using Plasma Channel Technology, Case Study: Yamama Formation, South of Iraq

Abstract


Introduction
The emerging technique of Plasma Channel Technology (PCT) holds promise in enhancing the petrophysical properties of carbonate reservoirs, revolutionizing oil exploration and production (Li et al., 2021) By utilizing controlled plasma channels, this method alters the internal rock structure on a microscopic scale, leading to improve permeability, porosity, and fluid flow within the carbonate formations (Li et al., 2021) Electro-pulse boring (EPB) has the high usefull of rock-fracture efficiency and enhance oil reservoir poroerties (Yan et al., 2016).A new method of rock-breaking with potential and close to petroleum industry was represented by (Kusaiynov et al., 2017).EPB is controlled by many parameters, like voltage, electrode structure shape, rock component, discharge times and so on (Wang et al., 2012).The high-energy particles of plasm interact with the rock, creating fractures, pores and modifying mineral compositions.This enhances fluid movement through the reservoir, boosting overall productivity (Li et al., 2021).
Sindbad oilfield is located 18 Km east of Basrah City and approximately 5 Km of the Iraq-Iran borders, between the lines easting (785451-787500) m, and northing (3388161-3389000) m, (Basrah Oil Company) (Fig. 1) (Table .1).There are two aims of applying Plasma Channel Technology for enhancing the petrophysical properties of reservoirs: one is improved reservoir permeability by creating controlled plasma channels within the body rock, the technique aims to increase the connectivity of pore spaces and fractures which enabling enhanced extraction of hydrocarbons whereas the other one is enhanced porosity and pore connectivity by interacting with the rock at a microscopic level, the plasma treatment aims to create additional pore spaces and enlarge existing ones.
Yamama Formation was deposited within the Early Cretaceous epoch.This geological period was represented from deep to shore by, Lower Balambo, Sarmord, Shuiaba, Yamama, Garagu, Ratawi and Zubair formations.By the stratigraphic position, the studied formation age probably from L. Beriassian to E. Valangenian (Jassim and Goff, 2006).Yamama Formation includes the neritic lithofacies of the cycle and was deposited in alternating oolitic shoal and deep inner shelf environment, probably controlled by structural highs within a carbonate ramp (Al-Zaidy and Al-Mafraji, 2019a) (Fig. 2).Geologically, the study area is lying within Zubair Subzone at the southern most unit of the Mesopotamian zone.This Subzone is bordered by a transversal fault zone of Takhadid-Qurna fault which formed during the L. Precambrian at the North, Al-Batin fault at the South or along the transversal fault in Kuwait and Salman zone from the west (Jasim and Goff, 2006).The aims of this study is to improve reservoir porosity and permeability by using the Plasma Channel Technology technique which then creating a connected channels in subsurface formations and enhancing fluid flow for efficient oil and gas recovery processes.

History of Using Plasma Channel Technology in Enhancing Reservoir Properties
Plasma Channel Technology has evolved as a groundbreaking approach to enhance reservoir properties in the oil and gas industry (Kozhevnikov et al., 2021).Its roots trace back to the early 2000s, with initial experiments exploring the use of plasma discharges to modify rock surfaces.Over the years, advancements in plasma science and engineering have led to the development of sophisticated tools for controlled application in rock fractures (Sun et al., 2015).This technology gained momentum in the 2010s as field trials demonstrated its potential in increasing porosity and permeability.Continuous research and innovation have refined the methodology, making Plasma Channel Technology as a promising solution for optimizing hydrocarbon recovery and addressing challenges in unconventional reservoirs.This technique is not only effective in terms of enhancing oil recovery but it is cost-effective along with environment-friendly where the success treatment depends on type, composition and rheological properties of crude oil and properties of reservoir In Iraq.It should be noted that this technique is not yet applied in Iraqi oil field .

Materials and Methods
The strategy of the methodology is represented by the following steps: The sampling stage was made by getting (20) core samples from the available of Yamama Formation which getting from two studied oil wells where each sample was 5 cm 3 in size.
These samples were checked and photographed by Scaning Electron Microscope (SEM) in Production Engineering and Metallurgy Lab in Technonlogy University (Baghdad) during two times, the fisrt one is before treated samples by EPB and the second after treated samples by EPB in order to delineate the difference between two stages.
Implementment Plasma Channel Technology which involves the controlled manipulation of plasma a state of matter consisting of charged particles to create a stable channel through which energy can propagate over long distances.This process begins with the creation of a plasma medium, achieved through various methods such as laser-induced breakdown or electrical discharges.

Principle of EPB Rock-Breaking
The EPB rock fracturing can be divided into 4 steps, as shown in Fig. 3.The 1 st step is a highvoltage short pulse on the electrode, where has increased time less than 500 ns.The rock is electric punctured in this stage.The 2 nd step generates a small discharge precursor inside the bed, such that the decrease range of voltage on the electrode in the circuit are small.The 3 rd step is ionization, when the precursor is developed due to pair of electrodes.The plasma channel connects the high and low voltage to make a main "discharge channel".The voltage on the high-voltage electrodes will decrease rapidly while the current in the circuit increases rapidly as well.In the 4 th step, the energy on the high voltage capacitor is released into the plasma channel and heats the channel.The plasma channel expands by heating, which works on the surrounding rock.When the stress exceeds the strength of the rock, it will break.The broken rock is returned to the ground by a circulating water medium to realize EPB .The design of the plasma pulse tool is metal wire as locking the electrodes conductor with diameter (0.45 mm) and length (30 mm) (Huang and Shi, 2020).

Methods of Measuring Porosity
The matching of any coated sample can be ascertained by measuring porosity size related features (Yan et al., 2016).This can be done by regarding many parameters, as : (a) the percentage porosity (Pm), (b) pore density per unit area (PDm), (c) maximum pore diameter (Dm), (d) equivalent pore radius (Rm).The above constitutes of pore system is given by" (Gerald and Yuantao, 2019).The models of evaluation and analysis can be broadly classified as the direct and indirect methods (Li et al., 2021).In the direct method, the samples are physically subjected to the measurement process, whereas in indirect methods, it is via imaging analysis of the sample.Most of the methods portrayed in Fig. 4."

Results
The quest for improved reservoir recovery and sustainable exploitation of hydrocarbons has driven innovation in unconventional techniques such as Plasma Channel Technology (PCT).Where the using (PCT) for enhancing petrophysical properties and enlarging pore space in reservoir rocks, with a particular focus on observations by SEM, as follow: Pore space enlargement: SEM observations of the PCT-treated rock samples revealed a substantial enlargement of pore spaces compared to the untreated control samples.These enlarged pores were uniformly distributed throughout the rock matrix, enabling improved connectivity and facilitating enhanced fluid flow pathways.Figs.5-10 illustrate the SEM micrographs of the untreated and treated samples, emphasizing the differences in pore space morphology.2. SEM micrographs vividly reveal the transformative effects of Plasma Channel Technology on rock samples.PCT-treated specimens exhibit distinct alterations in pore structures and surface morphology, providing valuable insights into the enhanced porosity and permeability that achieved through this innovative reservoir approach .
3. SEM micrographs unveil the internal structural changes in which it induced by Plasma Channel Technology on rock samples.The images show-case the modified pore distribution and surface intricacies, providing visual evidence of the improved porosity and permeability resulting from PCT treatment.
4. Enhanced porosity: Quantitative analyses of porosity confirmed the significant enhancement achieved through PCT.The treated sample exhibiting a noticeable increase in overall porosity compared to the control.This augmentation in porosity correlated well with the SEM observations, thereby reinforcing the credibility of the technology.
5. Improved permeability: Permeability tests conducted on the treated samples demonstrating a substantial enhancement in fluid flow characteristics.This improvement in permeability has direct implications for enhanced hydrocarbon recovery.

Discussion
The results obtained from this study provide robust evidence of the effectiveness of PCT in enhancing petrophysical properties and enlarging pore spaces in carbonate reservoir rocks, as observed by SEM where several key points emerge from the findings; Controlled and targeted pore enlargement: PCT offers a unique advantage in which it enables the precise and targeted enlargement of pore spaces within the rock matrix.This selectivity ensures that pore expansion which occurs only where needed, minimizing the risk of over-fracturing or damaging the reservoir rock.Improved pore connectivity: The enlarged pore spaces observed under SEM were not only larger but also interconnected.This enhanced connectivity between pores is pivotal, as it fosters more efficient fluid flow, reducing flow barriers and thereby improving overall reservoir productivity.
Environmental sustainability: Unlike conventional hydraulic fracturing methods, PCT minimize surface disturbances, reduces water usage and mitigates chemical releases into the environment.This aligns with the growing industry were trend towards responsible extraction practices and environmental stewardship.
Precision and reproducibility: PCT's controlled and reproducible nature makes it an attractive tool for reservoir recovery.The ability to fine-tune treatment parameters ensures that the technology can be optimized for specific reservoir conditions, offering a potential solution to reservoir-specific challenges.
Future research and applications: These results pave the way for further research and the real-world application of PCT within reservoir environments.Field trials and pilot studies are warranted to assess the technology's performance under actual reservoir conditions, validate its economic viability, and quantify the magnitude of enhanced hydrocarbon recovery.

Conclusions
The main conclusion that can presented in this study is underscored the potential of PCT for enhancing petrophysical properties and enlarging pore space within carbonate reservoir rocks.The SEM observations and quantitative analyses provide compelling evidence of PCT's efficacy as a transformative technology in reservoir enhancement practices.PCT's precision, environmental sustainability and potential for further applications position is a promising tool in the oil and gas industry's ongoing efforts to maximize hydrocarbon recovery while minimizing environmental impact.Further research, field testing and collaboration between industry and academia are essential steps toward unlocking the full potential of PCT and ensuring its successful integration into hydrocarbon exploration and production strategies.

Aknowledgements
Special appreciation to the Editorial Committee of the Iraqi Geological Journal for their unwavering commitment to academic excellence.Their diligent work and dedication to maintaining rigorous standards contribute significantly to the scholarly quality of the journal, fostering the advancement of geology in Iraq and beyond.

Fig. 1 .
Fig.1.The Location map of the studied oil field (modified from Handhal et al., 2020)

Fig. 2 .
Fig. 2. Stratigraphic column of the studied oil field showing the core interval in Snd-1

Fig. 3 .
Fig.3.Schematic showing the PCD concept and arrangement, i.e., the electrodes, the drilling fluid, and the rock.Phase I and Phase II show the plasma formation in the pores and the resultant pore space expansion.Phases III and IV show the plasma channel formation, expansion, and rock damage(Li et al., 2019)