Development of a New Correlation for Bubble Point Pressure in Oil Reservoirs Using Artificial Intelligent Technique

Oil production by natural energy of the reservoir is usually the first choice for oil reservoir development. Conversely, to effectively develop tight oil reservoir is challenging due to its ultra-low formation permeability. A novel platform for experimental investigation of oil recovery from tight sandstone oil reservoirs by pressure depletion has been proposed in this paper. A series of experiments were conducted to evaluate the effects of pressure depletion degree, pressure depletion rate, reservoir temperature, overburden pressure, formation pressure coefficient and crude oil properties on oil recovery by reservoir pressure depletion. In addition, the characteristics of pressure propagation during the reservoir depletion process were monitored and studied. The experimental results showed that oil recovery factor positively correlated with pressure depletion degree when reservoir pressure was above the bubble point pressure. Moreover, equal pressure depletion degree led to the same oil recovery factor regardless of different pressure depletion rate. However, it was noticed that faster pressure drop resulted in a higher oil recovery rate. For oil reservoir without dissolved gas (dead oil), oil recovery was 2–3% due to the limited reservoir natural energy. In contrast, depletion from live oil reservoir resulted in an increased recovery rate ranging from 11% to 18% due to the presence of dissolved gas. This is attributed to the fact that when reservoir pressure drops below the bubble point pressure, the dissolved gas expands and pushes the oil out of the rock pore spaces which significantly improves the oil recovery. From the pressure propagation curve, the reason for improved oil recovery is that when the reservoir pressure is lower than the bubble point pressure, the dissolved gas constantly separates and provides additional pressure gradient to displace oil. The present study will help engineers to have a better understanding of the drive mechanisms and influencing factors that affect development of tight oil reservoirs, especially for predicting oil recovery by reservoir pressure depletion.

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Physical Simulation and Mathematical Model of the Porous Flow Characteristics of Gas-Bearing Tight Oil Reservoirs

Energies ◽

10.3390/en14113121 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3121

Author(s):

Yuan Rao ◽

Zhengming Yang ◽

Yapu Zhang ◽

Zhenkai Wu ◽

Yutian Luo ◽

...

Keyword(s):

Oil Reservoirs ◽

Tight Oil ◽

Production Well ◽

Porous Flow ◽

Bubble Point ◽

Bubble Point Pressure ◽

Point Pressure ◽

Tight Oil Reservoirs ◽

Gas Bearing ◽

Solution Gas

The separation of solution gas has great influence on the development of gas-bearing tight oil reservoirs. In this study, physical simulation and high-pressure mercury intrusion were used to establish a method for determining the porous flow resistance gradient of gas-bearing tight oil reservoirs. A mathematical model suitable for injection–production well networks is established based on the streamline integral method. The concept of pseudo-bubble point pressure is proposed. The experimental results show that as the back pressure decreases from above the bubble point pressure to below the bubble point pressure, the solution gas separates out. During this process, the porous flow resistance gradient is initially equal to the threshold pressure gradient of the oil single-phase fluid, then it becomes relatively small and stable, and finally it increases rapidly and exponentially. The lower the permeability, the higher the pseudo-bubble point pressure, and the higher the resistance gradient under the same back pressure. For tight reservoirs, the production pressure should be maintained above the pseudo-bubble point pressure when the permeability is lower than a certain value. When the permeability is higher than a certain value, the pressure can be reduced below the pseudo-bubble point pressure, and there is a reasonable range. The mathematical results show that after degassing, the oil production rate and the effective utilization coefficient of oil wells decline rapidly. These declines occur later and have a flat trend for high permeability formations, and the production well pressure can be reduced to a lower level. Fracturing can effectively increase the oil production rate after degassing. A formation that cannot be utilized before fracturing because of the blocked throats due to the separation of the solution gas can also be utilized after fracturing. When the production well pressure is lower than the bubble point pressure, which is not too large, the fracturing effect is better.

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Development Features of Cold Production with Horizontal Wells in a Foamy Extra-Heavy Oil Reservoir

10.2118/200974-ms ◽

2021 ◽

Author(s):

Zhaopeng Yang ◽

Xingmin Li ◽

Xinxia Xu ◽

Yang Shen ◽

Xiaoxing Shi

Keyword(s):

Heavy Oil ◽

Horizontal Wells ◽

Oil Field ◽

Production Performance ◽

Oil Reservoirs ◽

Bubble Point ◽

Foamy Oil ◽

Bubble Point Pressure ◽

Heavy Oil Reservoirs ◽

Point Pressure

Abstract The block M as a foamy extra-heavy oil field in the Carabobo Area, the eastern Orinoco Belt, has been exploited by foamy oil cold production utilizing horizontal wells. The early producing area of block M has been put into production more than 10 years. And the development features of cold production in foamy extra-heavy oil reservoirs are different from the conventional oil field. It is necessary to investigate the development features of this kind reservoir and analyze its influence factors. Combining the production data with the reservoir geological characteristics of the research area, the cold production features of foamy extra-heavy oil using horizontal wells are analyzed. Then numerical simulations were adopted to study the influence factors of cold production performance. In the early stage of cold production, the oil production rate is high and the producing GOR is low. With the process of cold production, the reservoir pressure decreases gradually, the producing GOR increases gradually, and the oil production rate decreases gradually. When the bottom hole flowing pressure drops to below the bubble point pressure, the flow of extra-heavy oil in the reservoir can be divided into two zones: far well zone and near well area. In the far well zone, the pressure is higher than the bubble point pressure. The flow of oil is a single-phase flow, and the displacement mode is elastic driving. In the near well area, the pressure is lower than the bubble point pressure, and the oil flow is foamy oil flow, and the displacement mode is the dissolving gas drive driven by foamy oil. There exists many factors that influence the cold production performance of foamy extra-heavy oil, including reservoir depth, reservoir thickness, reservoir physical property and heterogeneity. The oil recovery factor per unit pressure drop can evaluate the cold production performance of foamy extra-heavy oil reservoirs. The effectiveness of cold production is closely related to reservoir parameters. Larger reservoir thickness, deeper reservoir depth and greater reservoir permeability will enhance the performance of cold production. Closer, larger and more interlayers above the horizontal well will hinder the performance of cold production. This research provides certain guidance and reference for further development adjustment and new project evaluation for foamy extra-heavy oil reservoirs in the Eastern Orinoco Belt.

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Committee Machine-Ensemble as a General Paradigm for Accurate Prediction of Bubble Point Pressure of Crude Oil

Journal of Energy Resources Technology ◽

10.1115/1.4047977 ◽

2020 ◽

Vol 143 (2) ◽

Author(s):

Sina Rashidi ◽

Mohammad Khajehesfandeari

Keyword(s):

Crude Oil ◽

Phase Region ◽

Accurate Prediction ◽

Oil Reservoirs ◽

Accurate Estimation ◽

Two Phase ◽

Committee Machine ◽

Bubble Point ◽

Bubble Point Pressure ◽

Point Pressure

Abstract Bubble point pressure (BPP) not only is a basic pressure–volume–temperature (PVT) parameter for calculation nearly all of the crude oil characteristics, but also determines phase-type of oil reservoirs, gas-to-oil ratio, oil formation volume factor, inflow performance relationship, and so on. Since the measurement of BPP of crude oil is an expensive and time-consuming experiment, this study develops a committee machine-ensemble (CME) paradigm for accurate estimation of this parameter from solution gas-oil ratio, reservoir temperature, gas specific gravity, and stock-tank oil gravity. Our CME approach is designed using a linear combination of predictions of four different expert systems. Unknown coefficients of this combination are adjusted through minimizing deviation between actual BPPs and their associated predictions using differential evolution and genetic algorithm. Our proposed CME paradigm is developed using 380 PVT datasets for crude oils from different geological regions. This novel intelligent paradigm estimates available experimental databank with excellent accuracy i.e., absolute average relative deviation (AARD) of 6.06% and regression coefficient (R2) of 0.98777. Accurate prediction of BPP using our CME paradigm decreases the risk of producing from a two-phase region of oil reservoirs.

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A new correlation for accurate prediction of oil formation volume factor at the bubble point pressure using Group Method of Data Handling approach

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2021.109410 ◽

2021 ◽

pp. 109410

Author(s):

Mohammed Abdalla Ayoub ◽

A. Elhadi ◽

Diab Fatherlhman ◽

M.O. Saleh ◽

Fahd Saeed Alakbari ◽

...

Keyword(s):

Accurate Prediction ◽

Group Method ◽

Data Handling ◽

Volume Factor ◽

Bubble Point ◽

Bubble Point Pressure ◽

New Correlation ◽

Oil Formation Volume Factor ◽

Point Pressure ◽

Oil Formation

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NEW DERIVED CORRELATIONS FOR LIBYAN CRUDE OIL TO ESTIMATE BUBBLE-POINT PRESSURE

Scientific Journal of Applied Sciences of Sabratha University ◽

10.47891/sabujas.v2i1.1-13 ◽

2019 ◽

Vol 2 (1) ◽

pp. 1-13

Author(s):

Mustafa Sharrad ◽

Hamid Hakim Abd-Alrahman

Keyword(s):

Crude Oil ◽

Oil Recovery ◽

Production Performance ◽

Petroleum Engineering ◽

Empirical Correlations ◽

Bubble Point ◽

Bubble Point Pressure ◽

New Correlation ◽

Future Production ◽

Point Pressure

The key factor of all petroleum engineering calculation is the knowledge of the PVT (Pressure, Volume, Temperature) parameters, such as determination of oil and gas flowing properties, predicting production performance in the future, production facilities designing and enhanced oil recovery planning methods. Those PVT properties are ideally determined experimentally in the laboratory. However, some of these experimental data is not always available; consequently, empirical correlations are used to estimate them. Many researchers have been focusing on models for predicting reservoir fluid properties from the available experimental PVT data, such as reservoir pressure, temperature, crude oil API gravity, gas oil ratio, formation volume factor, and gas gravity. The present study compares between some of the available empirical PVT correlations for estimating the bubble point pressure of some Libyan crude oils based on 35 data point samples from different Libyan oil fields. In the second part of this study, a new correlation has been derived to predict the bubble point pressure using Eviews software and compares the output results of this new correlation with some derived correlations found in the literature using statistical analysis such as the Average Absolute Error (AARE). The results showed an AARE as low as 8.7%, for bubble point pressure estimated by this new derived correlation. These results are valid to compare to other driven empirical correlations that have been evaluated.

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