A Quadruple-Porosity Model for Consistent Petrophysical Evaluation of Naturally Fractured Vuggy Reservoirs

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2678-2693
Author(s):  
Mahaman Salifou Aboubacar ◽  
Zhongxian Cai
Keyword(s):  
Water Saturation ◽  
Accurate Determination ◽  
Total Porosity ◽  
Fluid Systems ◽  
Proposed Model ◽  
Naturally Fractured ◽  
The Matrix ◽  
Input Variables ◽  
Porosity Model

Summary Several dual- and triple-porosity models have been proposed for quantifying the porosity exponent (m) in multiporosity reservoirs. Total porosity (ϕ) is usually portioned into the matrix (ϕb) and vuggy porosity, which includes separate vugs (SVGs) and connected vugs (CVGs). As a result, in their majority, the existing petrophysical models were developed and applied mostly without any distinction between the various types of CVGs despite their specific pore geometries, which critically determine the properties of the rock/fluid systems. For instance, unlike otherwise CVGs, natural fractures (NFs) and microcracks that have low pore-aspect-ratio values are highly compressible; this can cause their closure and lead to increasing m values. In this paper, we proposed a quadruple-porosity model that accounts for NFs (ϕ2 or ϕf) and CVGs (ϕc), in addition to ϕb and SVGs (ϕnc) separately, as distinct input variables to ensure accurate determination of m in composite reservoirs. The approach was based on the volume-model method and rules of electric-resistance networks in porous media. Computed water-saturation values used to validate the model show significant improvement and close agreement with the laboratory measurements, demonstrating the applicability of the proposed model for accurate prediction of m in naturally fractured vuggy reservoirs. New correlations that consider the pore-type diversity were generated using a plot of ϕ vs. m, obtained with the proposed quadruple-porosity model. The procedure involved sorting the ϕ/m scattering points using pore-type mixing and relative abundance of specific porosity. It allowed defining consistent ϕ/m relationships, with determination coefficients of 0.7 to 0.9. This suggests that m varies with the pore-structure types; this was further demonstrated with a rock-frame flexibility factor (γ) used as a proxy to cluster the scattering points. The established correlations can alternatively be applied to reasonably predict m using detailed prior knowledge of pore-type description.

scholarly journals Petrophysical Analysis of an Iraqi Gas Field (Mansuriya Gas Field)

2020 ◽  
Vol 26 (3) ◽  
pp. 100-116
Author(s):  
Hasan Saleh Azeez ◽  
Dr. Abdul Aali Al-Dabaj ◽  
Dr.Samaher Lazim
Keyword(s):  
Gamma Ray ◽  
Water Saturation ◽  
Total Porosity ◽  
Logarithmic Scale ◽  
Formation Factor ◽  
Gas Field ◽  
The Matrix ◽  
Rock Parameters ◽  
Potassium 40

Mansuriya Gas field is an elongated anticlinal structure aligned from NW to SE, about 25 km long and 5-6 km wide. Jeribe formation is considered the main reservoir where it contains condensate fluid and has a uniform thickness of about 60 m. The reservoir is significantly over-pressured, (TPOC, 2014). This research is about well logs analysis, which involves the determination of Archie petrophysical parameters, water saturation, porosity, permeability and lithology. The interpretations and cross plots are done using Interactive Petrophysics (IP) V3.5 software. The rock parameters (a, m and n) values are important in determining the water saturation where (m) can be calculated by plotting the porosity from core and the formation factor from core on logarithmic scale for both and the slope which represent (m) then Pickett plot method is used to determine the other parameters after calculating Rw from water analysis . The Matrix Identification (MID), M-N and Density-Neutron crossplots indicates that the lithology of Jeribe Formation consists of dolomite, limestone with some anhydrite also gas-trend is clear in the Jeribe Formation. The main reservoir, Jeribe Formation carbonate, is subdivided into 8 zones namely  J1 to J8, based mainly on porosity log (RHOB and NPHI) trend, DT trend and saturation trend.  Jeribe formation was considered to be clean in terms of shale content .The higher gamma ray because of the uranium component which is often associated with dolomitisationl and when it is removed and only comprises the thorium and potassium-40 contributions, showed the gamma response to be low compared to the total gamma ray response that also contains the uranium   contribution.While the Jeribe formation is considered to be clean in terms of shale content so the total porosity is equal to the effective porosity.No porosity cut off is found if cutoff permeability 0.01 md is applied while the porosity cut off approximately equal to 0.1 only for unit J6 & J8 if cutoff permeability 0.1 md is applied . It can be concluded that no saturation cutoff for the units of Jeribe formation is found after a cross plot between water saturation and log porosity for the reservoir units of Jeribe formation and applied the calculated cut off porosity. The permeability has been predicted using two methods: FZI and Classical, the two methods yield approximately the same results for all wells.

A Rapid and Accurate X-Ray Determination of the Rare Earths Elements in Solid or Liquid Materials using the Double Dilution Method

1968 ◽  
Vol 12 ◽  
pp. 546-562
Author(s):  
R. Tertian
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Accurate Determination ◽  
Fluorescence Analysis ◽  
Dilution Method ◽  
Practical Advantage ◽  
X Ray ◽  
The Matrix

AbstractThe double dilution method has many important advantages. For any element to be determined, let us say A, It enables us to control or calculate the matrix factor (sum of the absorption end enhancement effects) for the sample being Investigated towards A radiation, and it furnishes corrected Intensities which are strictly proportional to A concentration. Thus the results are exact, whatever the general composition of the sample, their accuracy depending only on the quality of measurement and preparation. Another major practical advantage is that the method does not require systematic calibration but only a few permanent standards consisting of a pure compound or of an accurately known sample.The procedure has been tested successfully for accurate determination of rare earth elements using, for solid materials such as ores and oxide mixtures, the borax fusion technique. It also can be readily applied to liquids. All the rare earth elements can be titrated by that method, as well as yttrium, thorium and, if necessary, all the elements relevant to X-ray fluorescence analysis. The concentration range considered for solids is of one comprised between 0.5 and 100 % and, with a lesser accuracy, between 0.1 and 0-5 % Examples are given relative to the analysis of various ores. Finally it rcust be pointed out that the method is universal and applies to the analysis of every solid, especially ores, provided that they can be converted to solid or liquid solutions. It appears that most industrial analyses can be worked on In this way.

scholarly journals Roll Attitude Determination of Spin Projectile Based on GPS and Magnetoresistive Sensor

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Dandan Yuan ◽  
Wenjun Yi ◽  
Jun Guan
Keyword(s):  
Mathematical Model ◽  
Attitude Determination ◽  
Accurate Determination ◽  
Blind Spot ◽  
Gps Measurements ◽  
Guidance And Control ◽  
Magnetoresistive Sensor ◽  
Proposed Model ◽  
And Control

Improvement in attack accuracy of the spin projectiles is a very significant objective, which increases the overall combat efficiency of projectiles. The accurate determination of the projectile roll attitude is the recent objective of the efficient guidance and control. The roll measurement system for the spin projectile is commonly based on the magnetoresistive sensor. It is well known that the magnetoresistive sensor produces a sinusoidally oscillating signal whose frequency slowly decays with time, besides the possibility of blind spot. On the other hand, absolute sensors such as GPS have fixed errors even though the update rates are generally low. To earn the benefit while eliminating weaknesses from both types of sensors, a mathematical model using filtering technique can be designed to integrate the magnetoresistive sensor and GPS measurements. In this paper, a mathematical model is developed to integrate the magnetoresistive sensor and GPS measurements in order to get an accurate prediction of projectile roll attitude in a real flight time. The proposed model is verified using numerical simulations, which illustrated that the accuracy of the roll attitude measurement is improved.

scholarly journals Using artificial neural networks to determine sediment concentration at limit of deposition in storm sewers

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Adhemar Romero ◽  
José Junji Ota
Keyword(s):  
Sediment Concentration ◽  
Percentage Error ◽  
Average Error ◽  
Volumetric Concentration ◽  
Proposed Model ◽  
Artificial Neural ◽  
Input Variables ◽  
Mlp Model ◽  
Storm Sewers

ABSTRACT The concept of sediment transport at the limit of deposition in storm sewers represents one operational condition that avoid deposition of sediments maintaining the discharge capacity of the pipes. In this study, this condition was analyzed applying one Artificial Neural Network Multilayer Perceptron (ANN-MLP) model to predict the volumetric concentration at the limit of deposition, using 544 experimental data from literature. It was evaluated different input variables combinations and model configurations, showing the sensitivity of the model with these changes. Through this study, it was demonstrated that the proposed model outperforms the existing equations, leading to more assertive predictions in the determination of volumetric concentrations at the limit of deposition, resulting in values of R2 = 0.92, Mean Absolute Percentage Error (MAPE) = 35.09 % and Mean Average Error (MAE) = 59.84 ppm. With the performed analysis, the study selects one equation to be used for extrapolations when determining the volumetric concentration at the limit of deposition in storm sewers. The selected equation is superior due to its theoretical basis. This work includes one more concept to a better methodology in obtaining the conditions of the flow at the limit of deposition.

scholarly journals Determination of Petrophysical Parameters of Reservoir Rock with a Special Look to Shale Effect (Case Study: One of the Gas Fields in Southern Iran)

2021 ◽  
Vol 5 (2) ◽  
pp. 1-10
Author(s):  
Taheri K
Keyword(s):  
Water Saturation ◽  
Accurate Determination ◽  
Reservoir Rock ◽  
Petrophysical Properties ◽  
Gas Reservoir ◽  
Reservoir Water ◽  
Petrophysical Parameters ◽  
Hydrocarbon Reservoir ◽  
Shale Volume

Determination of petrophysical parameters is necessary for modeling hydrocarbon reservoir rock. The petrophysical properties of rocks influenced mainly by the presence of clay in sedimentary environments. Accurate determination of reservoir quality and other petrophysical parameters such as porosity, type, and distribution of reservoir fluid, and lithology are based on evaluation and determination of shale volume. If the effect of shale volume in the formation not calculated and considered, it will have an apparent impact on the results of calculating the porosity and saturation of the reservoir water. This study performed due to the importance of shale in petrophysical calculations of this gas reservoir. The shale volume and its effect on determining the petrophysical properties and ignoring it studied in gas well P19. This evaluation was performed in Formations A and B at depths of 3363.77 to 3738.98 m with a thickness of 375 m using a probabilistic calculation method. The results of evaluations of this well without considering shale showed that the total porosity was 0.1 percent, the complete water saturation was 31 percent, and the active water saturation was 29 percent, which led to a 1 percent increase in effective porosity. The difference between water saturation values in Archie and Indonesia methods and 3.3 percent shale volume in the zones show that despite the low shale volume in Formations A and B, its effect on petrophysical parameters has been significant. The results showed that if the shale effect not seen in the evaluation of this gas reservoir, it can lead to significant errors in calculations and correct determination of petrophysical parameters.

Improvements in Simulation of Naturally Fractured Reservoirs

1983 ◽  
Vol 23 (04) ◽  
pp. 695-707 ◽  
Author(s):  
James R. Gilman ◽  
Hossein Kazemi
Keyword(s):  
Fluid Flow ◽  
Single Phase ◽  
Reservoir Rock ◽  
Storage Volume ◽  
Naturally Fractured ◽  
Matrix Blocks ◽  
The Matrix ◽  
Porosity Model ◽  
Made In ◽  
The Continuum

Abstract Simulation of multiphase flow in heterogeneous two-porosity reservoirs such as naturally fractured systems is a difficult problem. In the last several years much progress has been made in this area. This paper focuses on progress has been made in this area. This paper focuses on the practical aspects of that technology. It describes a stable, flexible, fully implicit, finite-difference simulator in heterogeneous, two-porosity reservoirs. Flow rates and wellbore pressures are solved simultaneously along with fracture and matrix fluid saturations and pressures at all grid points. Hydrodynamic pressure gradient is maintained at formation perforations in the wellbore. The simulator is accurate enough to match analytical solutions to single-phase problems. The equations have been extended to include polymer flooding and tracer transport with nine-point connection for determining severe local channeling and directional tendencies. It is shown that the two-porosity model presented in this paper will produce essentially the same answers as the paper will produce essentially the same answers as the common single-porosity model of a highly heterogeneous system but with a substantial reduction of computing time. In addition, this paper describes in detail several two-porosity parameters not fully discussed in previous publications. previous publications. Introduction Naturally fractured reservoir simulators are developed to simulate fluid flow in systems in which fractures are interconnected and provide the main flow path to injection and production wells. The fractures have high permeability and low storage volume, the reservoir rock permeability and low storage volume, the reservoir rock (matrix blocks) has low permeability and high storage volume. The idealization of assuming one porosity as the continuum can apply to many heterogeneous systems where one porosity provides the main path for fluid flow and the other porosity acts as a source. Throughout this paper, the fracture should be thought of as the continuum paper, the fracture should be thought of as the continuum and the matrix perceived as the adjacent sources or sinks. For single-phase flow of a gas or liquid, fluid compression and viscous forces control fluid movement. Gravity and capillary forces are not pertinent. Several single-phase idealizations that produce essentially the same practical engineering answers are discussed in the literature. Fig. 1 shows a model with both vertical and horizontal fractures. Separate nodes are used for fracture and matrix. For this case, 77 nodes are used to model the system. Fig. 2 also shows a model that allows vertical and horizontal fractures. However, this model requires far fewer nodes because areas in which the matrix blocks behave similarly are grouped in a single node. Each gridblock may contain many matrix blocks. The matrix blocks act as sources that feed into the fractures in a gridblock. The fractures can be thought of as a system of connected pipes. This model was proposed by Warren and Root. The boundary conditions used can make a dramatic difference in simulation results. Generally, we assume that only the fractures produce into the wellbore and are the path of fluid flow from one gridblock to the next. For multiphase flow, three forces must be properly accounted for--viscous, gravity, and capillary. In this case, we might require that the matrix blocks be further divided into grid blocks to obtain better definition of saturation distribution (Fig. 3). However, this will lead to additional work and may not be required. Kazemi et al. extended the Warren-Root model to multiphase systems to account for capillary and gravity forces. SPEJ P. 695

scholarly journals Determination of Chloramphenicol in Honey Using Salting-Out Assisted Liquid-Liquid Extraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry and Validation According to 2002/657 European Commission Decision

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3481 ◽  
Author(s):  
Serena Rizzo ◽  
Mariateresa Russo ◽  
Massimo Labra ◽  
Luca Campone ◽  
Luca Rastrelli
Keyword(s):  
Matrix Effects ◽  
Accurate Determination ◽  
Liquid Extraction ◽  
Natural Food ◽  
Bioactive Substances ◽  
Salting Out ◽  
Liquid Liquid Extraction ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass

Honey is a natural food widely consumed due to its high content in nutrients and bioactive substances. In order to prevent hive infections, xenobiotics such as pesticides and antibiotics are commonly used. Chloramphenicol (CAP) is a broad-spectrum antibiotic used to treat honeybee larvae diseases. However, CAP has toxic and nondose-dependent effects in sensitive subjects; for this reason, its use has been prohibited in food-producing animals, such as the honeybee. In this study, we proposed a rapid, simple, and cheap analytical method, based on salting-out assisted liquid-liquid extraction coupled with UHPLC MS/MS detection for the accurate determination of CAP in honey to be used in routine analyses. The parameters that influence the extraction efficiency have been optimized using an experimental design in order to maximize the recovery of the analyte by reducing the matrix effects. Therefore, the developed method was internally validated according to the 2002/657/EC Decision guidelines and applied to the analysis of 96 honey samples.

The Birgitta Field, Block 22/19a, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 371-381 ◽  
Author(s):  
G. Goffey
Keyword(s):  
North Sea ◽  
Water Saturation ◽  
Accurate Determination ◽  
Effective Porosity ◽  
High Pressure High Temperature ◽  
Elevated Water ◽  
Central North Sea ◽  
Resource Uncertainty ◽  
Pore Lining

AbstractBirgitta Field was discovered by well 22/19-1 which encountered a 230 ft gas–condensate column in Triassic Skagerrak Formation and tested at a combined rate of 38.3 MMscfgd and 3750 bcpd. The tilted-fault block trap forms the crest of a Triassic ‘pod’ or mini-basin formed by salt withdrawal during Triassic extension, further rotated and eroded during Jurassic extension. Field extent is supported by apparent seismic hydrocarbon indications. An early oil charge was likely converted to condensate by Plio-Pleistocene gas influx and rapid burial, whilst an underlying palaeoresidual gas column reflects some trap leakage.Birgitta typifies certain Triassic reservoir characteristics in this part of the Central North Sea. The thick, relatively high net:gross reservoir comprises moderate to poorly sorted, sub-lithic to sub-arkosic sandstones deposited in a dryland braided fluvial system. Pore-lining chlorite overgrowths dominate the pore fabric, reducing pore throat sizes and contributing to appreciable levels of non-effective micro-porosity and hence elevated water saturation. Key petrophysical challenges are the accurate determination of effective porosity and water saturation.Birgitta approaches high pressure–high temperature conditions and illustrates some of the challenges of progressing small, unappraised field tie-backs. These include resource uncertainty, compartmentalization risk, infrastructure access and marginal economics. Evaluated for development several times, Birgitta presently remains undeveloped.

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