Production optimization in a fractured carbonate reservoir with high producing GOR

The Gas-Oil Ratio(GOR)is a crucial production parameter in oil reservoirs.An increase in GOR results in higher gas production and lower oil production,potentially leading to well shut-ins due to economic infeasibility.This study focuses on a real fractured oil field that requires urgent production operations to reduce the producing GOR.In this study,the static model for the field was developed using commercial software,involving steps such as data collection,fault modeling,meshing,and statistical analysis to prepare for dynamic simulation.The dynamic model incorporates geometry,gridding,and rock properties from the static model,utilizing a dual-porosity approach for the naturally fractured reservoir and the Peng-Robinson equation for fluid phase behavior.Initial reservoir conditions,production history,and rock-fluid interactions were defined,with relative permeability curves indicating a water-wet reservoir and low critical gas saturation affecting the GOR.To better understand the relationship between reservoir and production parameters,a detailed sensitivity analysis was performed using the Response Surface Methodology(RSM).Following the sensitivity analysis,a history matching process was conducted using the Designed Exploration and Controlled Evolution(DECE)optimizer to validate the model for future forecasts.Six operational scenarios were defined to decrease the production GOR and enhance final recovery from the field.The results indicate that the water injection scenario is effective in preventing the GOR increase by maintaining reservoir pressure,thereby sustaining production over a longer period.This scenario also improves oil recovery by approximately 6%compared to the base case.Finally,optimization was carried out using the DECE optimizer for each scenario to fine-tune the operational parameters.The goal was to maximize oil revenue for each scenario during the optimization process.This study stands out as one of the few that provides a comprehensive analysis of production behavior and development planning for a real fractured reservoir with high producing GOR.

The deposition of asphaltenes under high-temperature and highpressure (HTHP) conditions

In this work,the factors affecting asphaltenes deposition in high-temperature and high-pressure wells were studied using backscattered light and PVT equipment customized to suit the well conditions.In an examination of the intensity of backscattered light,it was revealed that there exists a linear relationship between temperature and asphaltene precipitation within a specific temperature range.Within this range,a decrease in temperature tends to accelerate asphaltene precipitation.However,the impacts of pressure and gas-oil ratio are more pronounced.The pressure depletion induces the asphaltenes to precipitate out of the solution,followed by the formation of flocs below the bubble point.In addition,an increase in the gas-oil ratio causes a more severe asphaltene deposition,shifting the location of asphaltenes to deep well sections.

Application of Fluid Phase Recovery Method in the Early Development of BZ26-6 Volatile Oil Field in Bohai Sea

BZ26-6 Oilfield is a kind of deep metamorphic rock buried-hill volatile oilfield in Bohai Sea, China. Its early development plan is restricted due to the simultaneous production of oil and gas in large sections of reservoirs, unclear understanding of formation fluid properties and uncertainty of gas-oil interface. Through theoretical research on phase recovery and experimental analysis of crude oil phase characteristics in the original formation, characteristic parameters of the equilibrium condensate gas fluid are restored and calculated. Through the superimposed phase diagram of volatile oil and condensate gas, BZ26-6 Oilfield is determined to be a volatile oil reservoir with a condensate gas cap, with formation pressure and saturation pressure of 36.1 MPa, respectively. Based on the research results of oil-gas phase behavior characteristics, the thermodynamic equations and equation of state are jointly used to solve the problem, and the content change curves of each component at different depths are drawn. Combined with the sensitivity analysis of numerical simulation, the gas-oil interface is determined to be -3726 m above sea level. The fluid phase analysis software, Fluidmodeler, is used to simulate volatile oil degassing and condensate gas separation experiments. In combination with oil and gas production data obtained through the production test, the specific oil recovery index and the specific gas recovery index are determined to be 0.408 m3/(MPa·d·m) and 1195 m3/(MPa·d·m), respectively. And the reasonable production capacity prediction is conducted on the early development of BZ26-6 Oilfield. The research results can provide a theoretical basis for the efficient development of similar complex oil and gas reservoirs.