scholarly journals A New Approach in Pressure Transient Analysis: Using Numerical Density Derivatives to Improve Diagnosis of Flow Regimes and Estimation of Reservoir Properties for Multiple Phase Flow

2015 ◽  
Vol 2015 ◽  
pp. 1-16
Author(s):  
Victor Torkiowei Biu ◽  
Shi-Yi Zheng
Keyword(s):  
Empirical Model ◽  
Oil And Gas ◽  
Weighted Average ◽  
Fluid Phase ◽  
Numerical Density ◽  
Reservoir Properties ◽  
Flow Equations ◽  
Density Correlation ◽  
Multiple Phase ◽  
Derivatives Of

This paper presents the numerical density derivative approach (another phase of numerical welltesting) in which each fluid’s densities around the wellbore are measured and used to generate pressure equivalent for each phase using simplified pressure-density correlation, as well as new statistical derivative methods to determine each fluid phase’s permeabilities, and the average effective permeability for the system with a new empirical model. Also density related radial flow equations for each fluid phase are derived and semilog specialised plot of density versus Horner time is used to estimate k relative to each phase. Results from 2 examples of oil and gas condensate reservoirs show that the derivatives of the fluid phase pressure-densities equivalent display the same wellbore and reservoir fingerprint as the conventional bottom-hole pressure BPR method. It also indicates that the average effective kave ranges between 43 and 57 mD for scenarios (a) to (d) in Example 1.0 and 404 mD for scenarios (a) to (b) in Example 2.0 using the new fluid phase empirical model for K estimation. This is within the k value used in the simulation model and likewise that estimated from the conventional BPR method. Results also discovered that in all six scenarios investigated, the heavier fluid such as water and the weighted average pressure-density equivalent of all fluid gives exact effective k as the conventional BPR method. This approach provides an estimate of the possible fluid phase permeabilities and the % of each phase contribution to flow at a given point. Hence, at several dp' stabilisation points, the relative k can be generated.

Early-Time 1D Analysis of Shale-Oil and -Gas Flow

SPE Journal ◽  
2016 ◽  
Vol 21 (04) ◽  
pp. 1254-1262 ◽  
Author(s):  
Ali I. Bajwa ◽  
Martin J. Blunt
Keyword(s):  
Diffusion Equation ◽  
Gas Flow ◽  
Oil And Gas ◽  
Mathematical Formulation ◽  
Synthetic Data ◽  
Early Time ◽  
Spontaneous Imbibition ◽  
Reservoir Properties ◽  
Flow Equations ◽  
Fluid Properties

Summary We present a new semianalytic method to solve the nonlinear pressure-diffusion equation at early time, before reservoir boundaries are encountered, and under constant bottomhole pressure (BHP), applicable to the analysis of unconventional reservoirs. We assume that the flow rate is inversely proportional to the square root of time since the beginning of production. The method is an extension of the semianalytic solution proposed by Schmid et al. (2011) for spontaneous imbibition; we replace the solution for saturation with one for pressure, while extending the functional form of the governing diffusion equation. The solution can accommodate arbitrary pressure-dependent nonlinear rock and fluid properties as well as production caused by desorption. The mathematical formulation is presented for a general nonlinear case and tested by use of synthetic data. Field production from the Barnett Shale is then used to estimate effective matrix permeability. The model can be used to predict production if the rock and fluid properties are known, or can be used to constrain reservoir properties from production data. It is a complement to traditional pressure- or rate-transient analysis; if the response of a well for constant-pressure production can be determined, our method can be used to determine reservoir properties, without any approximations inherent in linearizing the flow equations.

Deep fluids and their role in hydrocarbon migration and oil deposit formation exemplified by supercritical СO2

2021 ◽  
pp. 1-11
Author(s):  
Sara LIFSHITS
Keyword(s):  
Supercritical Fluid ◽  
Oil And Gas ◽  
Gas Permeability ◽  
Sedimentary Rocks ◽  
Source Rocks ◽  
Reservoir Properties ◽  
Hydrocarbon Migration ◽  
Geological Processes ◽  
Before And After ◽  
Oil Source

ABSTRACT Hydrocarbon migration mechanism into a reservoir is one of the most controversial in oil and gas geology. The research aimed to study the effect of supercritical carbon dioxide (СО2) on the permeability of sedimentary rocks (carbonates, argillite, oil shale), which was assessed by the yield of chloroform extracts and gas permeability (carbonate, argillite) before and after the treatment of rocks with supercritical СО2. An increase in the permeability of dense potentially oil-source rocks has been noted, which is explained by the dissolution of carbonates to bicarbonates due to the high chemical activity of supercritical СО2 and water dissolved in it. Similarly, in geological processes, the introduction of deep supercritical fluid into sedimentary rocks can increase the permeability and, possibly, the porosity of rocks, which will facilitate the primary migration of hydrocarbons and improve the reservoir properties of the rocks. The considered mechanism of hydrocarbon migration in the flow of deep supercritical fluid makes it possible to revise the time and duration of the formation of gas–oil deposits decreasingly, as well as to explain features in the formation of various sources of hydrocarbons and observed inflow of oil into operating and exhausted wells.

A Z-number integrated weighted MULTIMO-ORA method for risk prioritization in FMEA

2021 ◽  
pp. 1-15
Author(s):  
Weizhong Wang ◽  
Yilin Ma ◽  
Shuli Liu
Keyword(s):  
Risk Analysis ◽  
Risk Evaluation ◽  
Oil And Gas ◽  
Weighted Average ◽  
Entropy Method ◽  
The Self ◽  
Analysis Problem ◽  
Risk Prioritization ◽  
Self Confidence ◽  
Evaluation Information

Current risk prioritization approaches for FMEA models are insufficient to cope with risk analysis problem in which the self-confidence of expert’s judgment and the deviation among risk evaluation information are considered, simultaneously. Therefore, to remedy this limitation, this paper reports an extended risk prioritization approach by integrating the MULTIMOORA approach, Z-numbers and power weighted average (PWA) operator. Firstly, the Z-numbers with triangular fuzzy numbers are applied to reflect the self-confidence and uncertainty of expert’s judgment. Next, the PWA operator for Z-numbers (Z-PWA) with similarity measure is proposed to obtain the group risk evaluation matrix by considering the influence of the deviation among risk evaluation information. Then, an extended version of MULTIMOORA method with developed entropy method is presented to calculate risk priority ranking order of each failure. Finally, the equipment failures in a certain oil and gas plant is utilized to test the extended risk prioritization approach for FMEA model. After that, the sensitivity and comparison studies are led to illustrate the availability and reliability of the proposed risk prioritization approach for FMEA based risk analysis problem.

Comparative analysis of production potential in Bulla-deniz and Umid gas-condensate fields

2020 ◽  
pp. 21-26
Author(s):  
E.H. Ahmadov ◽  
Keyword(s):  
Oil And Gas ◽  
Reduction Rate ◽  
Chemical Properties ◽  
Gas Production ◽  
Layer System ◽  
Reservoir Properties ◽  
Technical Parameters ◽  
Recovery Curves ◽  
Well Model ◽  
Drilling Technology

The paper studies the reduction rate of gas production in the wells of Bulla-deniz field drilled to VIII horizon. With this purpose, geological (reservoir properties, oil-gas saturation, net thickness, formation pressure and temperature, formation heterogeneity, multi-layer system, tectonic faults, physical-chemical properties of oil and gas etc.) and technological (well structure, measuring and transportation system, well operation regime, drilling technology etc.) conditions of formation were analyzed and the well model of VII and VIII horizons of Bulla-deniz field using these geological and technical parameters developed as well. For the estimation of impact of geological and technical aspects on production, sensitivity analysis was carried out on the models. The suggestions for elaboration of uncertainty of geological and technical parameters affecting production dynamics were developed. To reveal the reasons for production differences of the wells, it was proposed to install borehole manometers, to obtain the data on pressure recovery curves, drainage area, skin-effect impact, permeability and to develop a study plan of bottomhole zone with acid.

SECONDARY CHANGES IN CARBONATE ROCKS OF OIL AND GAS COMPLEXES

2020 ◽  
pp. 18-23
Author(s):  
M.A. Tugarova
Keyword(s):  
Carbonate Rocks ◽  
Oil And Gas ◽  
Carbonate Reservoirs ◽  
Fundamental Importance ◽  
Schematic Diagram ◽  
Reservoir Properties ◽  
Physico Chemical ◽  
Chemical Conditions ◽  
First Time

The article considers the secondary transformations of carbonate rocks of oil and gas complexes, which are of fundamental importance in the formation of reservoir properties. For the first time, a schematic diagram, illustrating the regularities of secondary processes in carbonate reservoirs and their relationship with the physico-chemical conditions of the stratosphere is proposed.

scholarly journals ASYMPTOTICALLY EFFICIENT ESTIMATION OF WEIGHTED AVERAGE DERIVATIVES WITH AN INTERVAL CENSORED VARIABLE

2016 ◽  
Vol 33 (5) ◽  
pp. 1218-1241 ◽  
Author(s):  
Hiroaki Kaido
Keyword(s):  
Support Function ◽  
Weighted Average ◽  
Interval Data ◽  
Efficient Estimation ◽  
Outcome Variable ◽  
Nonparametric Bounds ◽  
Regression Functions ◽  
Semiparametric Efficiency Bound ◽  
Derivatives Of ◽  
Interval Valued

This paper studies the identification and estimation of weighted average derivatives of conditional location functionals including conditional mean and conditional quantiles in settings where either the outcome variable or a regressor is interval-valued. Building on Manski and Tamer (2002, Econometrica 70(2), 519–546) who study nonparametric bounds for mean regression with interval data, we characterize the identified set of weighted average derivatives of regression functions. Since the weighted average derivatives do not rely on parametric specifications for the regression functions, the identified set is well-defined without any functional-form assumptions. Under general conditions, the identified set is compact and convex and hence admits characterization by its support function. Using this characterization, we derive the semiparametric efficiency bound of the support function when the outcome variable is interval-valued. Using mean regression as an example, we further demonstrate that the support function can be estimated in a regular manner by a computationally simple estimator and that the efficiency bound can be achieved.

A comprehensive analysis of conditions and features of oil-and-gas content within the Akhlovskaya structural zone (the North Caucasus)

2021 ◽  
pp. 25-38
Author(s):  
I. I. Bosikov ◽  
A. I. Mazko ◽  
A. V. Mayer ◽  
O. V. Gagarina
Keyword(s):  
Oil And Gas ◽  
Gas Content ◽  
North Caucasus ◽  
Reservoir Properties ◽  
Resource Base ◽  
Entire Area ◽  
The North ◽  
Urgent Task ◽  
Porosity Coefficient ◽  
Saturated Thickness

At the present stage, the development of the oil industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to analyze and assess the conditions and characteristics of oil-andgas content in unexplored regions.Purpose of the study is an analysis and an assessment of reservoir properties of rocks of the Aptian horizon Р1+2- К2 within the Akhlovskaya structure.We analyzed the graphs of the distribution of indicators in wells R-212 and R-213 in the Akhlovsky area and concluded that the reservoir is heterogeneous, and there are interlayers of mudstones with other reservoir properties and geophysical characteristics. The following pairs of parameters (porosity coefficient and oil-saturated thickness of rocks, rock resistivity and porosity coefficient, rock resistivity and oil-saturated thickness of rocks) have a significant positive correlation. Having studied the distribution of indicators in the Akhlovsky area for wells R-212 and R-213 along one horizon, we concluded that these indicators differ very slightly, which indicates the homogeneity of the reservoir properties. Qualitative indicators Qualitative indicators don't change. Thus, we can expect similar indicators within the entire area of the explored layer Р1+2- К2 in the territory of the Akhlovsky area.

Reservoir Quality Versus Completion Intensity: An Application of Supervised Fuzzy Clustering on Western Canadian Well Data

2021 ◽  
Author(s):  
Tamer Moussa ◽  
Hassan Dehghanpour ◽  
Melanie Popp
Keyword(s):  
Fuzzy Clustering ◽  
Oil And Gas ◽  
Approximate Reasoning ◽  
Design Parameters ◽  
Water Volume ◽  
Reservoir Quality ◽  
Reservoir Properties ◽  
High Quality ◽  
Tight Reservoirs ◽  
Well Data

ABSTRACT The industry is facing significant challenges due to the recent downturn in oil prices, particularly for the development of tight reservoirs. It is more critical than ever to 1) identify the sweet spots with less uncertainty and 2) optimize the completion-design parameters. The overall objective of this study is to quantify and compare the effects of reservoir quality and completion intensity on well productivity. We developed a supervised fuzzy clustering (SFC) algorithm to rank reservoir quality and completion intensity, and analyze their relative impacts on wells' productivity. We collected reservoir properties and completion-design parameters of 1,784 horizontal oil and gas wells completed in the Western Canadian Sedimentary Basin. Then, we used SFC to classify 1) reservoir quality represented by porosity, hydrocarbon saturation, net pay thickness and initial reservoir pressure; and 2) completion-design intensity represented by proppant concentration, number of stages and injected water volume per stage. Finally, we investigated the relative impacts of reservoir quality and completion intensity on wells' productivity in terms of first year cumulative barrel of oil equivalent (BOE). The results show that in low-quality reservoirs, wells' productivity follows reservoir quality. However, in high-quality reservoirs, the role of completion-design becomes significant, and the productivity can be deterred by inefficient completion design. The results suggest that in low-quality reservoirs, the productivity can be enhanced with less intense completion design, while in high-quality reservoirs, a more intense completion significantly enhances the productivity. Keywords Reservoir quality; completion intensity; supervised fuzzy clustering, approximate reasoning,tight reservoirs development

scholarly journals Multiphase plumes in a stratified ambient

2019 ◽  
Vol 869 ◽  
pp. 292-312 ◽  
Author(s):  
Nicola Mingotti ◽  
Andrew W. Woods
Keyword(s):  
Oil And Gas ◽  
Fluid Phase ◽  
Convective Transport ◽  
Maximum Depth ◽  
Buoyancy Flux ◽  
Return Flow ◽  
Ambient Fluid ◽  
Plume Height ◽  
Cylindrical Column ◽  
Fall Speed

We report on experiments of turbulent particle-laden plumes descending through a stratified environment. We show that provided the characteristic plume speed $(B_{0}N)^{1/4}$ exceeds the particle fall speed, where the plume buoyancy flux is $B_{0}$ and the Brunt–Väisälä frequency is $N$, then the plume is arrested by the stratification and initially intrudes at the neutral height associated with a single-phase plume of the same buoyancy flux. If the original fluid phase in the plume has density equal to that of the ambient fluid at the source, then as the particles sediment from the intruding fluid, the fluid finds itself buoyant and rises, ultimately intruding at a height of about $0.58\pm 0.03$ of the original plume height, consistent with new predictions we present based on classical plume theory. We generalise this result, and show that if the buoyancy flux at the source is composed of a fraction $F_{s}$ associated with the buoyancy of the source fluid, and a fraction $1-F_{s}$ from the particles, then following the sedimentation of the particles, the plume fluid intrudes at a height $(0.58+0.22F_{s}\pm 0.03)H_{t}$, where $H_{t}$ is the maximum plume height. This is key for predictions of the environmental impact of any material dissolved in the plume water which may originate from the particle load. We also show that the particles sediment at their fall speed through the fluid below the maximum depth of the plume as a cylindrical column whose area scales as the ratio of the particle flux at the source to the fall speed and concentration of particles in the plume at the maximum depth of the plume before it is arrested by the stratification. We demonstrate that there is negligible vertical transport of fluid in this cylindrical column, but a series of layers of high and low particle concentration develop in the column with a vertical spacing which is given by the ratio of the buoyancy of the particle load and the background buoyancy gradient. Small fluid intrusions develop at the side of the column associated with these layers, as dense parcels of particle-laden fluid convect downwards and then outward once the particles have sedimented from the fluid, with a lateral return flow drawing in ambient fluid. As a result, the pattern of particle-rich and particle-poor layers in the column gradually migrates upwards owing to the convective transport of particles between the particle-rich layers superposed on the background sedimentation. We consider the implications of the results for mixing by bubble plumes, for submarine blowouts of oil and gas and for the fate of plumes of waste particles discharged at the ocean surface during deep-sea mining.

scholarly journals Kinetics of saccharose fermentation by Kombucha

2014 ◽  
Vol 20 (3) ◽  
pp. 345-352 ◽  
Author(s):  
Eva Loncar ◽  
Katarina Kanuric ◽  
Radomir Malbasa ◽  
Mirjana Djuric ◽  
Spasenija Milanovic
Keyword(s):  
Empirical Model ◽  
Black Tea ◽  
Reaction Rates ◽  
Yeast Cells ◽  
Inoculum Concentration ◽  
Viable Cells ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Very High

Kinetics of saccharose fermentation by Kombucha is not yet well defined due to lack of knowledge of reaction mechanisms taking place during this process. In this research kinetics of saccharose fermentation by Kombucha was analysed using the suggested empirical model. The data were obtained on 1.5 g L-1 of black tea, with 66.47 g L-1 of saccharose and using 10% (v/v) or 15% (v/v) of Kombucha. Total number of viable cells was as follows: approximately 5x105 of yeast cells per mL of the inoculum and approximately 2x106 of bacteria cells per mL of the inoculum. The samples were analysed after 0, 3, 4, 5, 6, 7 and 10 days. Their pH values and contents of saccharose, glucose, fructose, total acids and ethanol were determined. A saccharose concentration model was defined as sigmoidal function at 22oC and 30oC, and with 10% (v/v) and 15% (v/v) of inoculum quantity. Determination coefficients of the functions were very high (R2>0.99). Reaction rates were calculated as first derivatives of Boltzmann?s functions. No simple correlation between rate of reaction and independent variables (temperature and inoculum concentration) was found. Analysis of empirical model indicated that saccharose fermentation by Kombucha occurred according to very complex kinetics.

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