Oil Zone Research Articles

Unlocking the Full Potential of NMR Using Machine Learning: A Case Study of a Gas Field With an Oil Problem

This paper describes the application of machine-learning techniques for unlocking the full potential of nuclear magnetic resonance (NMR), using a case study from the Seven Heads gas field. This field has long been recognized but was not developed due to a variety of technical challenges, including the thin-bedded nature of the sediments and the presence of both mobile and immobile viscous residual oil. The oil is a highly viscous liquid which, if produced, could block production tubing due to the shallow depth of the reservoir and associated low pressures. To produce dry gas successfully, identification of both oil and gas zones was necessary to enable gas zones to be perforated and oil zones to be excluded. During the development drilling campaign, the reservoir was appraised using a formation evaluation program specifically designed to address the presence of oil within the thinly bedded reservoir. In conjunction with core data and high-resolution electric logs, NMR logs were used to identify and avoid perforating zones with higher oil saturations. Formation fluid types were derived from the NMR using a pattern recognition technique that analyzes the entire shape of the T1 and T2 distributions to derive the volumes of gas, oil, and water. This machine-learning technique was calibrated using Dean and Stark fluid analysis data and enabled the prediction of continuous water, gas, and oil saturation curves. The results were used to ensure that the perforation strategy avoided oil-bearing sands. This paper describes how the NMR, together with machine learning, has enabled a complex tight gas field to be developed.

In Vitro evaluation of the Antimicrobial Activity of Thyme and Cinnamon Essential Oils against Respiratory Infection causing Bacteria and its Cytotoxicity Analysis

Respiratory tract infection (RTI) is among one of the common infections in human beings with life-threatening complications. Respiratory tract infection causes approximately 50 million deaths globally. The present study aimed to analyze two essential oils' anti-proliferative and antimicrobial activities against some common respiratory tract infection-causing microbes. The antibacterial activity of two essential oils including thyme and cinnamon oil, against the six RTI bacterial species, namely, Streptococcus pneumonia, Streptococcus pyogenes, Pseudomonas aeruginosa, Haemophilus influenza, Moraxella catarrhalis and Staphylococcus aureus, was assessed by cut well diffusion method. Cytotoxicity/anti-proliferative activity of essential oil (thyme and cinnamon) was investigated by using the SW480 cell line. The antibacterial activity of the oils was calculated by measuring the inhibitory zone and the maximum zone of 40.33 mm of cinnamon oil against H. influenza followed by a 40 mm zone of thyme oil against S. aureus and a minimum zone of 16.33 mm of cinnamon was observed against the S. pneumonia. The MIC value of the oils ranges from 0.10-0.60 mg/ml. The SW480 epithelial cells treated with the oils show an increase in cytotoxicity in a concentration-dependent manner. The in vitro cytotoxicity and antimicrobial activity results show that both the essential oils possess antimicrobial activity. The evidence shows that thyme oil has shown a little higher activity against respiratory tract infection. So, it can be used as an alternative to treat upper and lower respiratory infection-causing bacteria.

Predicting zones of separate oil and gas accumulation in Lower-Middle Cambrian Kuonamsky and Inikansky deposits of Eastern Siberia

Predicting zones of separate oil and gas accumulation in Lower-Middle Cambrian Kuonamsky and Inikansky deposits of Eastern Siberia

The search for new oil and CO

Residual oil zones (ROZs) could present a new, potentially large and commercially viable oil resource for Australia and provide an avenue for geological storage of carbon dioxide (CO2) through CO2 enhanced oil recovery (CO2-EOR). These reservoirs, which can contain a moderate amount of residual oil and resemble water-flooded oil fields, can be associated with conventional fields (brownfields) or occur with no associated main pay zone (greenfields). Both types of ROZ are currently produced commercially through CO2-EOR in the Permian Basin, USA, and are of growing interest internationally, but our understanding of the occurrence and economic viability of oil production from ROZs in Australia is limited. We are employing geological and petrophysical methods to identify, map and quantify the potential oil resources of ROZs, initially in central Australian basins. Complementing this, we are conducting a series of CO2 core-flooding experiments combined with reservoir modelling to investigate the techno-economic feasibility of producing oil and storing CO2 in these formations. We aim to establish and test a workflow for characterising and evaluating ROZs in Australia. ROZs could prove to be good targets for CO2-EOR+, potentially even producing carbon-neutral or carbon-negative oil by using CO2 from anthropogenic sources, such as from blue hydrogen production.

The role of deep faults in the structure formation of the TCFD, the distribution of hydrocarbon accumulations, and thermomineral sources

The work purpose was to assess the prospects of oil and gas potential of the western part of the Tersko-Caspian trough (TCT) concerning the development of deep-sunk areas in the light of modern ideas about the deep-seated formation of hydrocarbons. The main tasks are to analyze the ideas about the formation mechanism of the tectonic structure and formation of hydrocarbon accumulations; to study the relationships between the formation processes, migration, and the areal distribution of hydrocarbon accumulations; to determine the main prerequisites for the deep genesis of oil and gas. The scientific novelty lies in a comprehensive approach to the study of the formation processes of hydrocarbons, migration, the formation of traps, and patterns of placement of hydrocarbon accumulations. The article describes the mechanisms of formation of the Tersk and Sunzha composite anticline as the main zones of oil and gas accumulation. It is suggested that the formation of high-amplitude anticline folds in the upper cretaceous deposits resulted from the vertical migration of high-pressure fluids along deep faults with the breakthrough of their upper horizons of the sedimentary cover into the late-orogenic folding stages. The main prerequisites for the deep genesis of oil and gas are listed as pronounced uneven distribution of hydrocarbon accumulations, AHFP, hydrochemical anomalies, etc.

Dynamic track model of miscible CO2 geological utilizations with complex microscopic pore-throat structures

Monitoring field-scale CO2 geological utilizations is of paramount importance but challenging due to the complexities in microscopic heterogeneity. In this paper, complex geological characterizations and fluid properties are specifically analysed and a prediction model is developed, which is capable to track the dynamic behaviour of miscible CO2 multiphase flow in microscopically-heterogeneous porous media. More specifically, first, pore-throat sizes and distributions were characterised from the constant-rate mercury injection and the CO2-displacement seepage resistance was evaluated from a capillary bundle model. The differences of seepage resistance caused from the throat changing and coupling diffusion-dissolution effects and viscosity-resistance reductions were specifically studied in the process of continuous miscible CO2 displacement. Accordingly, a comprehensive mathematical model was developed with the time-node analysis method and validated through comparison with the experimental results. The leading edge of CO2 displacement as well as the timing of gas breakthrough and displacement completion are determined to be different with varying throat sizes. It is further found that the gas breakthrough time and the time required to complete the displacement are reduced with increasing throat size and their differences also decrease. Moreover, the interval area of injection and production wells could be characterised as pure CO2, diffusion and pure oil zones, whose positions could be dynamically tracked from the recovery performance. The calculated oil recovery and gas-oil ratio from the developed model share good agreement with experimental results, with deviations of 2.2 and 0.7%. Such the validated mathematical model is then applied to successfully predict the dynamic performance of an actual reservoir (H3).

Numerical Modeling of the Steam Chamber Ramp-Up Phase in Steam-Assisted Gravity Drainage

Due to the critical nature of the ramp-up phase of an efficient steam-assisted gravity drainage (SAGD) process, it is important to understand the physics of the steam chamber ramp-up phase in order to improve SAGD production performance. In conventional numerical simulation models, the dynamics of the steam chamber ramp-up phase are not fully resolved because of unclear steam–oil–water interactions during the vertical growth of the steam chamber and how its state changes as the reservoir parameters vary. This work provides an efficient approach for the numerical modeling of the steam chamber ramp-up phase in an SAGD operation. The steam chamber ramp-up phase was fully examined through the consideration of the effects of the temperature-dependent oil–water–gas multiphase flow system and the vertical countercurrent flow. The simulation results revealed that for the large temperature gradient of the mobile oil zone at the edge of the steam chamber, a delicate temperature-dependent multiphase flow system was essential for the reliable estimation of the SAGD ramp-up phase. The vertical countercurrent flows of oil–gas and oil–condensate were the dominant mechanisms over cocurrent flow, which significantly impacted the steam chamber ramp-up rate. The numerical model physically predicted the steam chamber ramp-up phase and could be used to efficiently compute a field-scale simulation using a dynamic gridding function that was based on a fine grid model.

Occurrence of water and thermogenic gas from oil-bearing formations in groundwater near the Orcutt Oil Field, California, USA

Study regionSanta Barbara County, California, USA. Study focusTo analyze a wide array of newly collected chemical, isotopic, dissolved gas, and age dating tracers in conjunction with historical data from groundwater and oil wells to determine if water and/or thermogenic gas from oil-bearing formations have mixed with groundwater in the Orcutt Oil Field and surrounding area. New hydrological insights for the regionThree of 15 groundwater samples had compositions indicating potential mixing with water and/or thermogenic gas from oil-bearing formations. Relevant indicators included salinity tracers (TDS, Cl, Br), NH3, DOC, enriched δ13C-DIC, δ2H-CH4, δ13C-CH4, and δ13C-C2H6 values, and trace amounts of C3-C5 gas. The potential sources/pathways for oil-bearing formation water and/or thermogenic gas in groundwater overlying and adjacent to the Orcutt Oil Field include: (1) upward movement from formations developed for oil production due to: (a) natural migration; or (b) anthropogenic activity such as injection and/or movement along wellbores; and (2) oil and gas shows in overlying non-producing oil-bearing formations. Groundwater age tracers, elevated 4He concentrations, and isotopic compositions of noble gases indicated legacy produced water ponds were not a source. This phase of the study relied on samples and data from existing infrastructure. Additional data on potential end-member compositions from new and existing wells and assessments of potential vertical head gradients and pathways between oil and groundwater zones may yield additional insight.

Lower-Middle Cambrian deposits of Bakhtinsky mega-uplift and neighbouring areas: geological models and prediction of oil and gas accumulation zones

Lower-Middle Cambrian deposits of Bakhtinsky mega-uplift and neighbouring areas: geological models and prediction of oil and gas accumulation zones

Selective penetration behavior of microgels in superpermeable channels and reservoir matrices

Gel treatment is an effective way to attack excessive water production in many mature oilfields around the world. Selective penetration is desired for successful gel treatments. That is, gel materials should easily penetrate the target zones (i.e., channeling features such as superpermeable channels) without entering/damaging the nontarget zones (i.e., reservoir matrices or oil zones). This study revealed that presence of threshold penetration pressure (ΔPth) was responsible for selective penetration behavior of tested microgels. The concept of ΔPth was utilized to figure out favorable working conditions for effective gel treatments. Microgel dispersions were injected into superpermeable (super-k) sandpacks (mimicking super-k channels in reservoirs, 60–221 darcies), heterogeneous models with super-k channels (79–230 darcies), and sandstone cores (mimicking reservoir matrices, 50–5000 md). The results demonstrated that a minimum differential driving pressure (i.e., threshold penetration pressure, ΔPth) was required to push microgel particles to penetrate channels or matrices. The critical penetration behavior was closely related to the particle/pore size ratio. Low ΔPth at smaller particle/pore ratios was beneficial to allow easy penetration of gel materials into the channeling zones. On the contrary, high ΔPth at larger particle/pore ratios was desirable to prevent gel materials from massively invading and damaging the matrices. Instead, the gel particles accumulated at the inlet surface, and a gel cake was gradually formed. The cake further prevented the invasion of the gels. The cake could be removed by chemical breakers to resume the injectivity/productivity of the matrices. Correlations were developed to describe the relationship between ΔPth and particle/pore ratio. A distinct transition was identified at the particle/pore ratio of about 3. This work could help identify the favorable conditions to achieve successful gel treatments. In an effective conformance treatment, the particle/pore ratio in the channel should be sufficiently low to allow easy penetration of gel materials into the channel (e.g., particle/pore ratio<2 in this study). Meanwhile, the particle/pore ratio in the matrix should be large enough to support a high ΔPth and thus prevent massive gel invasion into the matrix. This study advances the current pore scale studies (a single particle passing through a single channel) to Darcy-scale characterization.

A technical turning point-based framework to optimize CO2 EOR-storage: Capacity dynamics of Brownfield Residual Oil Zones

Residual Oil Zones (ROZs) contains considerable oil at residual saturation underlying Main Pay Zones (MPZs), which renders its development challenging in conventional manner. Enhanced oil recovery (EOR), for example, CO2 injection is therefore introduced. This technique unleashes the potentials of ROZs in terms of EOR and carbon storage. In field-scale simulation regard, although some researchers have investigated the effects of several operational variables such as well pattern, perforation interval, injection mode and injection strategy, on CO2 EOR-storage performances, no published work attempts to reveal the EOR-storage capacity dynamics/variations of Brownfield ROZ reservoir upon its development. By addressing the questions: (1) when to start considering ROZ expansion beyond MPZ; (2) the timing when to perform ROZ expansion that could maximize the profit; (3) whether ROZ expansion always benefits the project; (4) what development strategy is more favorable given a certain CO2 availability, this paper reveals the incentives of when to include ROZ into CO2 EOR-storage project beyond MPZ in development strategy regard. Based on the envisioned technical turning point where ROZ outperforms MPZ assuming propensity to oil production, novel performance metrics—ROZ oil production critical point (ROZ-OPCP) and ROZ opportune oil production trade-off point (ROZ-OOPTP), are brought up to technically optimize the development strategy design of Brownfield ROZ reservoir, upon which a resultant designing framework is established. The concepts and framework are envisioned to facilitate development strategy configurations, narrow down the target range for optimization, reduce the cost of trial-and-error and therefore promote the Carbon Capture and Storage (CCS). Simulation study also provides following insights on CO2 EOR-storage in Brownfield ROZ reservoir: (1) above ROZ-OPCP, the development of ROZ beyond MPZ is technically feasible under moderate and sufficient CO2 supply case since positive surpluses in EOR-storage are observed. Project could benefit most from sequential and simultaneous MPZ-ROZ development under moderate and sufficient CO2 supply case, respectively; (2) ROZ expansion without considerable CO2 availability and opportune timing could technically and economically impair the project, and ROZ-OOPTP needs to be considered herein; (3) Designing CO2 injection scenarios requires compromises. e.g., Higher injection rate in ROZ increases CO2 storage and brings forward the peak EOR-storage performance, while the lower injection rate prolongs the desirable EOR-storage performance; (4) The envisioned technical turning point and the CO2 EOR-storage capacity dynamics may strongly depend on original quality of ROZ and the current usage of MPZ, and less usage would lead to later occurrence of technical turning point.

Enhancing vertical resolution with 4D seismic inversion

In this work, we applied a Bayesian time-lapse (4D) seismic inversion to a deep-water heavy oil field located in the Campos Basin (Brazil). In this procedure, the differences of seismic amplitudes of baseline and repeated surveys are the input to calculate the changes in acoustic impedances. To ensure the quality of the results, the parametrization of the inversion was performed by analyzing the anomalies resolution and signal-to-noise ratio with different values of input parameters, and the estimates are crosschecked with the results of a petroelastic modeling applied to the dynamic model. Results show a relevant improvement in the vertical resolution of estimated acoustic impedances in comparison to the amplitude data in a thin reservoir (with thickness ranging from 15 to 45 m). This improvement was possible because of the high-quality of acquired seismic amplitudes (permanent reservoir monitoring) and because of the data variability that is controlled in the Bayesian 4D inversion algorithm. The high resolution of Bayesian inverted results enabled a more detailed vertical zoning of the reservoir, revealing important geological features, such as channels in the main interval and below the reservoir's base, and improved the understanding of the fluid movement over time, enabling the analysis of the injection efficiency and by-passed oil zones as well as the aquifer movement. This information is important to update the static model, by improving the definition of geological features, and to calibrate dynamic models, in the future, by adding the inverted acoustic impedance maps into the data assimilation procedure.

Estimation of the Influence of Oil Flows on the Formation Losses of Condensate During the Development of Multi-Layer Deposits

During the development of multilayer oil and gas condensate fields, the production of condensate is influenced by the associated oil. Analysis of field data showed that the cause of oil flows is the outstripping decrease in reservoir pressure in the gas condensate section in comparison with oil zones. Thus, incoming heavy oil fractions into a gas condensate reservoir have a negative impact on reservoir losses of hydrocarbons, including the final condensate recovery factor. Many years of experience in the development of such fields showed that the bulk of the presence of associated oil in well production is explained by the following reasons: the relationship between the reservoirs through lithological windows, the residual oil saturation of the reservoirs, and the presence of lenticular layers. Determination of the quantitative content of oil in the reservoir mixture was determined by infrared spectrometry using a Perkin-Elmer Fourier transform spectrometer, which makes it possible to assess changes in the component composition of gas condensate systems. In the course of the research, selected samples of the gas and liquid phases were analyzed directly from the production facilities of the development. The analysis of IR spectrometry showed that in most of the samples of gas condensates, the effect of displacement is recorded, which is characteristic of fluids with the manifestation of oil impurities.The purpose of these studies is to study the influence of the produced oil on the dynamics of hydrocarbon production and the final condensate recovery factor.

Enrichment control factors and exploration potential of lacustrine shale oil and gas: A case study of Jurassic in the Fuling area of the Sichuan Basin

Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow (7.5 × 104 m3/d gas and 9.8 m3/d oil) from the Middle Jurassic Lianggaoshan Formation, presenting a good test production effects, which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin. In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas, this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells, such as wells Taiye 1 and Fuye 10. Then, the main factors controlling the enrichment of lacustrine shale oil and gas are discussed, and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined. And the following research results are obtained. First, the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance, high porosity and high gas content, and it is the geological base of shale oil and gas enrichment. Second, the developed large wide and gentle syncline, good preservation condition and higher pressure coefficient (generally >1.2) are the key to the enrichment and high yield of shale oil and gas. Third, the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas. In conclusion, the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth, developed microfractures and moderate thermal evolution, and its shale gas resource extent and shale oil resource extent are 1 922 × 108 m3 and 2800 × 104 t, respectively, indicating greater potential of shale oil and gas exploration, so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.

Water injection front estimation of oil fields to reduce risks of sharp water flooding

At the fields of Rosneft Oil and Gas Company, effective technologies are used to increase oil production and oil recovery ratio. To this end, systematic work is carried out to extract hard-to-recover oil reserves. Side boreholes (BS) cutting, which helps to increase oil recovery and actually replaces well compaction. Piezometric and unprofitable wells, as well as wells with leaking production strings, are identified when selecting candidate wells for planning BS and horizontal wells (HW). Maps of residual oil-saturated thicknesses are also considered, according to which localization zones of oil reserves not involved in the development are determined, in order to select areas for drilling. For rational selection of measures, forecasting of drilling results should be carried out using a hydrodynamic model and full seismic studies. First of all, the proximity of the water injection front from the existing injection pool of wells is determined in order to avoid the risks of sharp watering.

Dissolved Metal (Fe, Mn, Zn, Ni, Cu, Co, Cd, Pb) and Metalloid (As, Sb) in Snow Water across a 2800 km Latitudinal Profile of Western Siberia: Impact of Local Pollution and Global Transfer

Snow cover is known to be an efficient and unique natural archive of atmospheric input and an indicator of ecosystem status. In high latitude regions, thawing of snow provides a sizable contribution of dissolved trace metals to the hydrological network. Towards a better understanding of natural and anthropogenic control on heavy metals and metalloid input from the atmosphere to the inland waters of Siberian arctic and subarctic regions, we measured chemical composition of dissolved (&lt;0.22 µm) fractions of snow across a 2800 km south–north gradient in Western Siberia. Iron, Mn, Co, Ni, and Cd demonstrated sizable (by a factor of 4–7) decrease in concentration northward, which can be explained by a decrease in overall population density and the influence of dry aerosol deposition. Many elements (Mn, Ni, Cu, Cd, Pb, As, and Sb) exhibited a prominent local maximum (a factor of 2–3) in the zone of intensive oil and gas extraction (61–62° N latitudinal belt), which can be linked to gas flaring and fly ash deposition. Overall, the snow water chemical composition reflected both local and global (long-range) atmospheric transfer processes. Based on mass balance calculation, we demonstrate that the winter time atmospheric input represents sizable contribution to the riverine export fluxes of dissolved (&lt;0.45 µm) Mn, Co, Zn, Cd, Pb, and Sb during springtime and can appreciably shape the hydrochemical composition of the Ob River main stem and tributaries.

Оценка коллекторских свойств карбонатных пород Юрубчено-Тохомской зоны нефтегазонакопления

The article is devoted to the study of reservoir properties of productive Riphean sediments within the Yurubcheno- Tokhomskaya oil and gas accumulation zone. The description of the filtration-capacity properties of the deposits is given, the structure and characteristics of the void space are investigated. The influence of fracturing and cavernousness on the development and forecast of the productivity of deposits has been investigated.

Evaluation and Reactivation Strategy of Shut-In Wells Due to High Water Cut to Improve Oil Production in Bayu Field: Case Study of Bayu-N3 Well

Bayu-N3 was being shut-in (S/I) due to excessive water production (high water cut well) as the main cause of the high daily production decline of the well. Therefore, an integrated analysis was conducted to identify the source of excessive water production and handle the problem. The reactivation strategy of Bayu-N3 was well planned to solve and optimize the oil production of the well. Based on integrated analysis of Chan’s diagnostic plot and cement evaluation log (CBL-VDL-USIT) data, the source of excessive water production at Bayu-N3 is water channeling, caused by the free pipe condition as the result of poor cement bonding between the casing and the formation. To handle the water channeling problem, remedial cementing was conducted to repair the cement bonding quality. Based on the C/O log evaluation at Bayu-N3 as the reactivation well candidate, there are six potential oil zones to be produced. The reactivation strategy was executed by perforating at interval 6544-6564 ft-MD and resulting 1602 BOPD with 0% of water cut. The economic analysis of the reactivation shows that Bayu-N3 well gives 5153 MUSD of NPV and 538% of IRR with one month and 29 days of POT. It is shows that the reactivation strategy of Bayu-N3 is technically and economically able to improve the oil production and gives good positive economic indicators. Furthermore, the successful of reactivation strategy in Bayu-N3 well could be used as reference to be implemented for other candidate wells in Bayu Field.

SUPLEMENTATION OF VIRGIN COCONUT OIL (VCO) PRODUCTS WITH INTARAN (Azadirachta indica) LEAF EXTRACT IN INHIBITING THE GROWTH OF ACNE BACTERIA Propianibacterium acnes

&lt;p&gt;The dangers of resistance to Propionibacterium acnes and the high cost of treatment prompted the discovery of medicinal sources from natural substances that could act as antibacterials. One of them is using post-harvest coconut products in the form of virgin coconut oil (VCO) with extract of intaran leaves (Azadirachta indica). The purpose of this study was to determine the phytochemical characteristics, inhibition zone and their categorization and to study the difference or effect of VCO supplemented with extracts of intaran leaves (Azadirachta indica) with various concentrations on the growth of Propionibacterium acnes. This study used a posttestonly control group design. The VCO mixed with extracts of intaran leaves with various concentrations of 5%, 10%, 15%, 20% and 25%. The antibacterial test was carried out using the Kirby-Bauer disc diffusion method. Data analysis used the Kruskall Wallis and Mann Whitney test. The VCO mixture supplemented with extracts of intaran leaves showed the presence of tannins, flavonoids, terpenoids, saponins, and alkaloids. The mean diameter of the inhibition zone of virgin coconut oil (VCO) supplemented with leaf extract at a concentration of 5%, 10%, 15%, 20% and 25% of the growth of P. acnes is 9.4 mm; 18.3 mm; 9.9 mm; 12.6 mm; and 9.9 mm. Data analysis showed that there were differences and the effect of adding extracts to the resulting inhibition zone diameter. The concentrations of leaf extract of 5%, 15%, and 25% were classified as moderate, while the concentrations of 10% and 20% of leaf extract were classified as strong. The 10% concentration had the highest inhibition zone diameter in inhibiting the growth of P. acnes. This combination has the potential to treat acne and needs to be carried out in vivo research.&lt;/p&gt;

Microstructural wettability of oil and gas condensate zones of the Karachaganak field

The Karachaganak field is represented by gas condensate and oil zones, a convenient object for studying changes in microstructural wettability during the transition from one zone to another. Microstructural wettability was characterized by a hydrophobization coefficient, Ѳн, which determines the proportion of the pore surface area occupied by adsorbed hydrocarbons. It was found that Ѳн of the samples of the gas and gas condensate zones is the same (on average 0.140), the oil zone - on average 0.250. Analysis of the IR spectra of extracted hydrocarbons showed that the microstructural wettability of the oil zone contains more aromatic, aliphatic, oxidized and sulfur-containing structures and fewer branched structures than in the gas condensate zone. The microstructural wettability of carbonate reservoirs depends on the hydrocarbon composition of the adsorbed oil. Keywords: microstructural wettability; hydrophobic coefficient; hydrocarbons; spectral coefficients.