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Maintaining the reservoir pressure by gas injection is frequently adopted in the development of gas condensate reservoir. The aim of this work is to investigate the phase behavior of condensate oil and remaining condensate gas in the formation under gas injection. The DZT gas condensate reservoir in East China is taken as an example. The multiple contact calculation based on cell-to-cell method and phase equilibrium calculations based on PR Equation of State (EOS) were utilized to evaluate the displacement mechanism and phase behavior change. The research results show that different pure gas has different miscible mechanism in the displacement of condensate oil: vaporizing gas drive for N2 and CH4; condensing gas drive for CO2 and C2H6. Meanwhile, there is a vaporing gas drive rather than a condensing gas drive for injecting produced gas. When the condensate oil is mixed with 0.44 mole fraction of produced gas, the phase behavior of the petroleum mixture reverses, and the condensate oil is converted to condensate gas. About the reinjection of produced gas, the enrichment ability of hydrocarbons is better than that of no-hydrocarbons. After injecting produced gas, retrograde condensation is more difficult to occur, and the remaining condensate gas develops toward dry gas.

The water-flooded zone in a sandstone reservoir with a complex porosity–permeability relationship is difficult to interpret quantitatively. Taking the P Formation of Kalamkas Oilfield in Kazakhstan as an example, this paper proposed a reservoir classification method that introduces the J-function into the crossplot of resistivity and oil column height to realize the classification of sandstone reservoirs with a complex porosity–permeability relationship. Based on the classification results, the initial resistivity calculation models of classified reservoirs were established. The oil–water seepage experiment was performed for classified reservoirs to measure the lithoelectric parameters and establish the relationship between water production rate and resistivity for these reservoirs, and then water production was quantitatively calculated according to the difference between the inverted initial resistivity and the measured resistivity. The results show that the reservoirs with an unclear porosity–permeability relationship can be classified by applying the J-function corresponding to grouped capillary pressure curves to the crossplot of oil column height and resistivity, according to the group average principle of capillary pressure curves. This method can solve the problem that difficult reservoir classification caused by a weak porosity–permeability correlation. Moreover, based on the results of reservoir classification, the water production rate and resistivity model of classified reservoirs is established. In this way, the accuracy of quantitative interpretation of the water-flooded zone in the reservoir can be greatly improved.

The re-injection of associated sour gas, with high H2S and CO2 content, into the reservoir is proposed to be an effective development method due to its low investment cost and high oil recovery. The aim of this work is to present the phase behavior and miscible mechanism of crude oil displaced by associated sour gas. Based on the equation of state and the phase equilibrium theory, the phase behavior of crude oil mixed with various gases (associated sour gas, H2S, CO2 and CH4) have been analyzed. Then, the miscibility of associated sour gas was determined by calculating its Minimum Miscible Pressure (MMP) and the effect of sour component fraction on miscibility was evaluated. Moreover, a series of numerical simulations modeling 1D slim-tube were conducted using a compositional simulator to study the miscible mechanism in the displacement of crude oil with associated sour gas. The results show that the injection of H2S can reduce the bubble point pressure of crude oil and therefore is beneficial to prevent the crude oil degassing; nevertheless, the injection of CO2 has little effect on it. The miscible ability of associated sour gas decreases as its sour component fraction decreases. It is observed that the crude oil displaced by associated sour gas and sweet gas both show a combined condensing/vaporizing mechanism, with miscible zone in the middle of transition zone. However, the vaporizing-gas drive mechanism is slightly stronger than the condensing-gas drive mechanism during the displacement by associated sour gas while is significantly stronger during the displacement by sweet gas.

Accurate calculation of heat efficiency in the process of superheated steam injection is important for the efficient development of heavy oil reservoirs. In this paper, an integrated analytical model for wellbore heat efficiency, reservoir heat efficiency and total heat efficiency was proposed based on energy conservation principle. Comparisons have been made between the new model results, measured data and Computer Modelling Group (CMG) results for a specific heavy oil reservoir developed by superheated steam injection, and similarity is observed, which verifies the correctness of the new model. After the new model is validated, the effect of injection rate and reservoir thickness on wellbore heat efficiency and reservoir heat efficiency are analyzed. The results show that the wellbore heat efficiency increases with injection time. The larger the injection rate is, the higher the wellbore heat efficiency. However, the reservoir heat efficiency decreases with injection time and the injection rate has little impact on it. The reservoir thickness has no effect on wellbore heat efficiency, but the reservoir heat efficiency and total heat efficiency increase with the reservoir thickness rising.

For the A South and Γ North reservoir of Zhanzhol oil field in Kazakhstan, only the oil rim was developed since 1983. Recently, the gas cap of A South reservoir was exploited in September, 2014. However, the concurrent production of gas cap and oil rim is likely to cause the pressure imbalance, which will lead to the worse development effect of the whole reservoir. In order to acquire the efficient concurrent production of gas cap and oil rim, the technique policy charts of concurrent production are established, involving three types of development mode such as depletion development, barrier water injection development and barrier plus pattern water injection development. For depletion development, rational oil recovery rate increases with rational gas recovery rate; for barrier water injection development, the rational position of barrier water injection well moves towards the inner oil-gas contact with the increase of gas recovery rate and injection-production ratio; for barrier plus pattern water injection development, the rational ratio of barrier water injection to pattern water injection increases with gas recovery rate and injection-production ratio. By improving the well network of barrier plus pattern water flooding and the ratio of barrier water injection to pattern water injection, the concurrent of oil rim and gas cap of A South reservoir was carried out. Furthermore, 2.3 billion of natural gas was yielded yearly. The control degree of water flooding of oil rim was enhanced; the natural decline rate of oil rim decreased and the development effect of oil rim improved greatly.

The central layer Yu-III in Akshabulak oilfield is a sandstone reservoir with strong edge water, whose major development characteristics are high oil recovery rate and heterogeneous water invasion. Aiming at this problem, the development policy chart of concurrent displacement of natural water and injected water is established on the basis of material balance principle. Injection-production ratio and oil recovery rate are the main controlling factors for the concurrent displacement of natural water and injected water. Each injection-production ratio corresponds with only one rational oil recovery rate, and the rational oil recovery rate increases with the injection-production ratio. When the actual injection-production ratio of the central Yu-III reservoir is 0.9, the rational oil recovery rate should be 4%.

Using fixed well patterns and constant water injection rates over extended periods in multilayered sandstone reservoirs often leads to uneven performance across different layers. Some layers may be over-saturated with water, while others may not be sufficiently swept, resulting in inefficient oil recovery. Furthermore, this causes poor overall utilization of the reservoir, with certain areas left upswept. To improve waterflooding efficiency and improve oil recovery, this study presents two well pattern adjustment methods that employ variable injection and production rates constraints: Rotational Injection and Rotational Production (RIRP) and Zonal Injection and Rotational Production (ZIRP). The effectiveness of these methods was demonstrated through pore-scale experiments and numerical reservoir simulations. Results show that at a reservoir scale, RIRP changes how water flows by creating pressure changes over time, facilitating fluid movement between and within each layer more effectively. At pore scale, both RIRP and ZIRP increase capillary forces, which help redistribute oil and water in the rock pores. Compared to the traditional commingled injection and zonal production (CIZP) method, RIRP and ZIRP perform better, increasing oil recovery by 3–7.6% and reducing water cut by 1.6–11.5%. This study also presents three operating cycles for each of the RIRP and ZIRP methods. Field data show that these techniques can significantly increase oil production, making them effective options for improving oil recovery in mature reservoirs during high water cut periods.

Chemical enhanced oil recovery (EOR) methods are shown to sweep the residual oil by altering physical properties of fluids after waterflooding to improve oil recovery. This work presents an experimental study on the surfactant/polymer injection for EOR in sandstone reservoirs. Interfacial tension measurements, emulsification and rheology tests are performed to select the best candidates from thirteen commercial surfactants and five commercial polymers. The performance of the preferred surfactant and polymer candidates in EOR is evaluated through a series of core flooding experiments on both homogeneous and heterogenous sand packs. Different injection schemes are investigated. The results show that the polymer injection and polymer-surfactant-mixture slug can effectively displace the residual oil as the polymer injection improves efficiency of the sweeping front. Core flooding experiments on the heterogenous sand pack show that injecting polymer in the first, followed by surfactant slug yields the better performance compared with combined polymer-surfactant-mixture injection as the polymer pre-flush improves the vertical conformance of the surfactant solution and the final recovery.

The 3-D ECOMSED ocean model was applied to establish a time-dependent boundary model for Jiaozhou Bay （JZB）, in which the operator-splitting technique was used and the ＇dry and wet＇ method was introduced. The influence caused by JZB reclamation on the surface level, residual currents, tidal system and tidal energy of M2 tidal system were predicted and analyzed. The results show that JZB reclamation has slight impact on the M2 tidal system, in which the variation of amplitude and phase is less than 1%.The changes of the currents and residual currents in Qian Bay and near the reclamation areas are greater, but in other areas the changes are smaller, in which the currents have a change of around 1%, while the residual currents change ranges from 1.82%-9.61% After reclamation, the tidal energy fluxes increase by 2.62%--5.24% inside and outside the JZB mouth, but decrease by 20.21%--8723% near Qian Bay and the reclamation area.

N6-methyladenosine (m6A) is a reversible mRNA modification that has been shown to play important roles in various biological processes. However, the roles of m6A modification in macrophages are still unknown. Here, we discover that ablation of Mettl3 in myeloid cells promotes tumour growth and metastasis in vivo. In contrast to wild-type mice, Mettl3-deficient mice show increased M1/M2-like tumour-associated macrophage and regulatory T cell infiltration into tumours. m6A sequencing reveals that loss of METTL3 impairs the YTHDF1-mediated translation of SPRED2, which enhances the activation of NF-kB and STAT3 through the ERK pathway, leading to increased tumour growth and metastasis. Furthermore, the therapeutic efficacy of PD-1 checkpoint blockade is attenuated in Mettl3-deficient mice, identifying METTL3 as a potential therapeutic target for tumour immunotherapy. N6-methyladenosine (m6A) is a reversible mRNA modification with important roles in cancer biology and immunoregulation. Here, the authors show that myeloid-specific deletion of Mettl3, the catalytic subunit of the methyltransferase complex, promotes tumor growth and metastasis in preclinical tumor models, influencing macrophage reprogramming and attenuating PD-1 blockade.