Determination of the Asphaltene Precipitation Envelope and Bubble Point Pressure for a Mexican Crude Oil by Scanning Transitiometry

2013 ◽  
Vol 27 (3) ◽  
pp. 1212-1222 ◽  
Author(s):  
Marco A. Aquino-Olivos ◽  
Jean-Pierre E. Grolier ◽  
Stanislaw L. Randzio ◽  
Adriana J. Aguirre-Gutiérrez ◽  
Fernando García-Sánchez
Author(s):  
Amir Tabzar ◽  
Mohammad Fathinasab ◽  
Afshin Salehi ◽  
Babak Bahrami ◽  
Amir H. Mohammadi

Asphaltene precipitation in reservoirs during production and Enhanced Oil Recovery (EOR) can cause serious problems that lead to reduction of reservoir fluid production. In order to study asphaltene tendency to precipitate and change in flow rate as a function of distance from wellbore, an equation of state (Peng-Robinson) based model namely Nghiem et al.’s model has been employed in this study. The heaviest components of crude oil are separated into two parts: The first portion is considered as non-precipitating component (C31A+) and the second one is considered as precipitating component (C31B+) and the precipitated asphaltene is considered as pure solid. For determination of the acentric factor and critical properties, Lee-Kesler and Twu correlations are employed, respectively. In this study, a multiphase flow (oil, gas and asphaltene) model for an asphaltenic crude oil for which asphaltene is considered as solid particles (precipitated, flocculated and deposited particles), has been developed. Furthermore, effect of asphaltene precipitation on porosity and permeability reduction has been studied. Results of this study indicate that asphaltene tendency to precipitate increases and permeability of porous medium decreases by increasing oil flow rate in under-saturated oil reservoirs and dropping reservoir pressure under bubble point pressure. On the other hand, asphaltene tendency to precipitate decreases with pressure reduction to a level lower than bubble point pressure where asphaltene starts to dissolve back into oil phase. Moreover, it is observed that precipitation zone around the wellbore develops with time as pressure declines to bubble point pressure (production rate increases up). Also, there is an equilibrium area near wellbore region at which reservoir fluid properties such as UAOP (Upper Asphaltene Onset Pressure) and LAOP (Lower Asphaltene Onset Pressure) are constant and independent of the distance from wellbore.


2019 ◽  
Vol 3 (2) ◽  
pp. 87
Author(s):  
Dikky Fathurochman Sidiq ◽  
Lestari Said

<p>Determination of the initial oil content of a reservoir starts from exploration activities. In the initial stage, the determination of the initial oil reserves is determined. This aims to determine whether the project can be profitable for the company or not. Over time the determination of the initial contents of the oil continues to be carried out to improve the accuracy of calculations using the material balance method.<br />In the reservoir "ADZ" the type of reservoir is an undersaturated reservoir. This is because the initial pressure in 1980 was 2762.74 psia, while the bubble point pressure was 1625.8 psia. Until 2015 this reservoir was still above the bubble point pressure with a pressure of 1783.55 psia, this reservoir also had no gas cap in the initial conditions. The drive mechanism that works on this field is the solution for the gas drive.<br />Calculation of the initial content of oil in this final project uses 4 methods, namely volumetric method, material balance method, straight line, and Mbal software. Using the volumetric method, the initial oil reserves obtained at the place amounted to 174063462 STB, while the calculation of the initial oil reserves in place using the material balance method was 176497285 STB. The percentage difference in the initial content of oil between the methods is &lt;5%.</p>


2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Sina Rashidi ◽  
Mohammad Khajehesfandeari

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.


Author(s):  
Mustafa Sharrad ◽  
Hamid Hakim Abd-Alrahman

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. 


Sign in / Sign up

Export Citation Format

Share Document