Table of contentsIntroductionDiscussion of the problemMaterials and methodologyProgress and resultsIntroductionDiagenesis has been described as a term that encompasses all sets of biological, physical and chemical processes, which act and transform the sediments from the initial stage of deposition until just before metamorphism. Nader (2017). The important role of diagenesis in geological systems in the creation and destruction of porosity via pore-clogging dissolution and cementation has been recognized for many decades (Zhang et al., 2017), a key concept and recent field Of keen interest in diagenetic studies (traceable to the increased and continued exploration of boundaries in the deepest parts of basins), is the diagenetic field of deep burial. Say no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get the original essayThis is characterized by the action of very aggressive pond fluids that create many processes, such as cementation, dissolution and recrystallization, which act to define the ultimate petrophysical pathway of reservoirs (Moore, 2001). The investigation into this unknown area extends from traditional or classical approaches using petrographic and field characterization techniques, to more sophisticated and advanced stages involving quantitative and experimental approaches with the use of advanced microscopy such as electron microscopy scanning, computed tomography (CT -Scan) and other computer-assisted techniques with modeling, for proper evaluation and understanding of the process (Giles, 1997; Nader, 2017). One of the most important factors influencing deep-buried diagenesis that merits our critical evaluation is the presence of liquid hydrocarbons in reservoir rocks (Choquette and James, 1987). It was Johnson (1920), cited in (Bukar, 2013), who first revealed the role that hydrocarbons can play in the diagenesis of reservoir rocks by inhibition of cementation. Since then, this topic has remained a matter of growing concern and interest, with numerous analyzes and investigations using various case studies (Worden et al., 1998; Neilson and Oxtoby, 2008; Bukar, 2013; Kolchugin et al. , 2016). . But also with some controversies and uncertainties, such as the debate on oil-inhibited cementation, questions regarding the source and transport of the enormous volume of CaCo3 during diageneis. The unusual increase in porosity-permeability in the North Sea Fulmar Formation much more than the average expected at their depth, based on the global trend in porosity depth (Wilkinson and Haszeldine, 2011), as well as in the Kharaib Formation, in Abu Dhabi (Neilson et al., 1998) and many other reservoirs, provided a very strong basis beyond the influence of excessive pressure, to agree with the school of thought that oil can inhibit cementation. However, on the other hand, the presence of oil inclusions (Fig. 1) as well as the absence of change or contrasting porosity between the oil and water legs in some reservoirs have served as a basis for doubting or contradicting the theory of cementation by petroleum inhibition. giving rise to the second school of thought which emphasizes that oil does not inhibit cementation (Bjorkum et al., 1993). A is the view in plane polarized light. B is the same image in cathodeluminescence view. (Caja et al., 2006). It is important to note that fluids play a very important role during diagenesis; they can act as transport agents, dissolve andreprecipitate the cements during this process. It therefore follows that the presence of hydrocarbons which are also a fluid in their own right may also be likely to significantly affect diagenesis. Generally, according to Worden et al (1998), oil can affect diagenesis in any or all of the following processes. I. By hindering or reducing the flow path for mass transport, this can limit cementation to the thin film of irreducible saturation water on the rock grains. The efficiency of all these processes and the degree of Cement inhibition depends on the timing and level of hydrocarbon saturation as well as the wettability of the reservoirs. (Worden et al., 1998; Kolchugin et al., 2016). The case studies that demonstrated that oil cannot inhibit cementing are likely those in which oil placement occurred late, after cementing had already occurred. But one thing certainly remains, that the fate of diagenesis never remains the same when oil enters the system, oil can restrict the aqueous phase flow and mass transfer processes, making the pore network tortuous or coating the grains in the reservoir in a moist oil. system (Worden et al., 1998) reducing cementation. 1. 3. The kinetics and thermodynamics of calcite growth and cementation It is known that most limestones have depositional porosities of around 40 to 70%, Pray and Choquette (1969), Prajpti et al (2017 ), but this is generally reduced to < 5% with little or no contribution from compaction (Bathurst, 1970; Prajapati et al., 2017), this reduction has serious implications for the role of carbonate cementation in occlusion porous spaces during limestone diagenesis. Understanding the kinetics and thermodynamics of calcite precipitation using our inorganic geochemical toolbox will be essential for establishing the rate of cementation of calcite in geologic processes. The growth and development of calcite is believed to occur in three stages (Helt 1978): I. Formation of a supersaturated solution II. Crystal nucleation III. Crystal growth. Crystal nucleation involves the assembly of ions to form particles for further growth and is considered the first step in calcite precipitation. Particles with nuclei below the critical size are dissolved in the solution, while those above this threshold determine the rate of crystal formation. growth. Where K is a constant, p the number of molecules required to assemble to form a critical nucleus, I is the induction time required for a nucleus of critical size to be assembled, and C the initial concentration of the supersaturated solution . After formation, the crystals start to grow by surface propagation on the formed critical nuclei, based on the classical and non-classical theorem. The classical theorem establishes the growth of crystals by the incorporation of monomers by attachment and detachment at the active sites of the crystal planes. The key processes are adsorption, surface energy differential and diffusion. Experimental studies of calcite growth rate are either performed using calcite or other materials as the nucleation site (seeded approach) or unseeded, resulting in spontaneous crystallization (Rybacki 2010). Seeded experiments are best for studying the growth rate of crystals (Rybacki 2010), because they allow the process to be monitored gradually before crystallization takes place rather than occurring instantly. A number of seeded experiments were carried out(Jaho et al., 2015; Declet et al., 2016 etc; Liszka et al., 2016) using various combinations such as the reaction of calcium chloride and sodium bicarbonate with rocks and glass particles. in flow experiments based on Darcy's law, given by: Q= KA. dh/dL Where Q is the fluid flow rate, K is the hydraulic constant, A is the cross section and dh/dL is the hydraulic gradient. (Hubbert, 1956) These experiments showed that the rate of growth and precipitation of calcite is mainly influenced by the saturation level (ca+), temperature, pH, ionic activity and the nature of the nucleation substrate ( Rybacki, 2010; Calcite precipitation occurs in a slightly to highly alkaline environment, but becomes erratic above pH >10; experimental work has observed optimal precipitation between pH 7.5 and 9.0. (Ruiz-Agudo et al., 2011; Declet et al., 2016). According to Declet et al (2016), too large or excessive increase in pH reduces the surface concentration necessary for calcite growth and increases supersaturation which also reduces particle size. Higher supersaturation increases the nucleation rate while forming smaller crystals, in contrast to lower supersaturations with lower rate but larger crystals (Jaho et al., 2015). Experiments on the influence of temperature revealed that temperature plays a role in the polymorphic distribution of calcite crystals. Calcite is more favored at lower ambient temperatures and comparable to the aragonite polymorph which predominates around 800 (Morse et al., 2007). Another means by which calcite can be precipitated is through the process of microbe-induced calcite precipitation (Ashraf et al., 2017; Cheng and Shahin, 2019). This is an efficient process of approximately 90% of the calcite precipitation conversion mechanism in less than a day (Al-Thawadi 2011 cited from Ashraf et al, 2017). However, at higher concentrations of calcium ions, urease activity can stop urea hydrolysis. An increase in temperature from 20 to 60°C can promote urease activity, but a decrease is observed above 70°C due to deactivation of the enzyme (whiffin 2004 cited by Ashraf et al , 2017). In order to avoid the by-products and relics of microbes from adding to the porosity occlusion, the precipitation and growth mechanism of inorganic calcite is preferred in this work. Discussion of the Problem The lack of appropriate accessibility to petroleum reservoirs due to their size and burial inevitably results in the sampling of only a fraction of the reservoirs. Geologists must then rely heavily on subsurface modeling to determine the distribution of porosity and permeability in reservoirs. But for such models to be accurate, a thorough understanding of the controls and parameters that influence diagenesis, such as the presence of oil in the subsurface, should be clearly known and taken into account in the applied models. Our understanding of the effect of the presence of oil during diagenesis on inhibition of cementation is well known and demonstrated ( Neilson et al., 1998 ; Worden et al., 1998 ; Kolchugin et al., 2016 ), but the conclusions have been largely limited to qualitative and are mainly based on petrographic data. Indeed, other influential factors such as capillary pressure, oil composition, and mineralogical variations between the oil and water segments are rarely fully considered (Worden et al., 1998). This leads to a biased and less accurate estimate of the impact of oil on cementation. The key question is.