Carbazoles and benzocarbazoles confirm migration of leaked petroleum through caprocks and overlaying formations of Valhall Well 2/8-8 in the North Sea

A wildcat may not result in a petroleum prospect;however, it may indicate potential need for frontier exploration, since petroleum could leak into economic accumulations. Carbazoles and benzocarbazoles are nitrogen compounds in petroleum and can be employed to explicitly explain migration direction and distance of leaking petroleum. The hypothesis of this study is that the mechanism of the reaction involving the attraction of carbazoles to clay minerals on the matrix of the walls along their migration pathways determines the isomer that is preferentially attached to the mineral matrix. The objectives of this study are(a) to produce a profile for carbazoles and benzocarbazoles ratios in the cap rock overlying the reservoir,(b) to compare carbazole and benzocarbazole ratios to 20S/(20S+20R) aaa C_(29) Sterane maturity ratios(c) to infer migration direction from the carbazoles and benzocarbazoles ratio. Samples used were side wall cores and drill cuttings of water-based mud drilling. The EOM(extractable organic matter) from various formations overlying the reservoir was obtained using Soxtherm Automatic Equipment. The TPH(total petroleum hydrocarbon) was obtained from the EOM by using a precleaned isolute C_(18) 500 mg/3 mL column, eluted with hexane, while the polars were eluted with dichloromethane. Fractionation into saturates and aromatics was done using a silver nitrate–silica gelcolumn. The profiles of 1,8/1,3 and 1,8/2,4 dimethyl carbazoles and the benzocarbazoles ratios show a vertical gradient of decreasing ratio with increasing vertical distance from the reservoir. This corroborates the %VRo equivalent of 20S/(20S+20R) aaa C_(29) Sterane and the carbazole ratios infer vertical migration of leaked petroleum.

Petrophysical characterization and 3D seismic interpretation of reservoirs in the Baris Field,onshore Niger Delta Basin,Nigeria

In order to evaluate the petrophysical properties,characterize the structural framework and determine the hydrocarbon in place of potential reservoirs in the Baris Field,onshore Niger Delta Basin,Nigeria,3D seismic and well log data from the field were collected and interpreted using Geographix and Petrel software.Two reservoir zones B2 and B5 were identified having porosity ranging from 21%to 22%,permeability from 235 to 523 mD and water saturation from 16%to 28%.Petrophysical parameters show that the two zones are good reservoirs and highly petroliferous.Seismic interpretation revealed the presence of six listric faults,two major faults(F1 and F2 trending in the northwestesoutheast direction)and four minor faults(F3,F4,F5 and F6).Faults 3,4 and 5 trend in the same direction as the major faults,while fault 6 trends in the northeastesouthwest direction.Two major horizons were identified,and they correspond to the two reservoir tops(B2_top and B5_top).Roll-over anticlinal structures between the two major listric faults were identified.The depositional environment of the Reservoirs B2 and B5 have been deciphered to be of a barrier bar or crevasse play and the trapping mechanism in the Baris Field is a four-way structural closure.STOOIP and GIIP for the two zones have been estimated with the zone B5 more prolific with a STOOIP and GIIP of 7.98MMSTB and 12.77MMMSCF respectively.

Pore pressure prediction in offshore Niger delta using data-driven approach: Implications on drilling and reservoir quality

Despite exploration and production success in Niger Delta,several failed wells have been encountered due to overpressures.Hence,it is very essential to understand the spatial distribution of pore pressure and the generating mechanisms in order to mitigate the pitfalls that might arise during drilling.This research provides estimates of pore pressure along three offshore wells using the Eaton's transit time method,multi-layer perceptron artificial neural network(MLP-ANN)and random forest regression(RFR)algorithms.Our results show that there are three pressure magnitude regimes:normal pressure zone(hydrostatic pressure),transition pressure zone(slightly above hydrostatic pressure),and over pressured zone(significantly above hydrostatic pressure).The top of the geopressured zone(2873 mbRT or 9425.853 ft)averagely marks the onset of overpressurization with the excess pore pressure above hydrostatic pressure(P∗)varying averagely along the three wells between 1.06−24.75 MPa.The results from the three methods are self-consistent with strong correlation between the Eaton's method and the two machine learning models.The models have high accuracy of about>97%,low mean absolute percentage error(MAPE<3%)and coefficient of determination(R2>0.98).Our results have also shown that the principal generating mechanisms responsible for high pore pressure in the offshore Niger Delta are disequilibrium compaction,unloading(fluid expansion)and shale diagenesis.

地震沉积学研究中的方法和技术

地震沉积学是基于高精度三维地震资料、现代沉积环境、露头和钻井岩心资料建立的沉积环境模式的联合反馈,是用以识别沉积单元的三维几何形态、内部结构和沉积过程的一种新的方法、技术体系.地震岩性学与地震地貌学是地震沉积学的核心组成部分,前者研究的方法、技术主要包括:测井约束反演、90°相位转换等,后者主要包括:基于沉积模型的地震正演模拟、地层切片、属性分析、频域滤波和分频解释等,这些技术已经广泛应用在沉积体分析、沉积过程分析、定量储层表征上,并取得了良好的效果.

各向异性TI介质qP反射波走时层析成像

地震走时层析成像是反演地层各向异性参数分布的有效方法,但是关于地震各向异性介质走时层析成像的研究并不多,其技术远远没有达到成熟的阶段.在野外数据采集时,地表反射波观测方式相对井间和垂直地震剖面观测方式的成本更低,利用qP反射波走时反演各向异性参数具有更加广泛的实用价值.本文实现的TI介质地震走时层析成像方法结合了TI介质反射波射线追踪算法、走时扰动方程和非线性共轭梯度算法,它可以对任意强度的TI介质模型进行反演,文中尝试利用qP反射波走时重建TI介质模型的参数图像.利用qP反射波对层状介质模型和块状异常体模型进行走时反演,由于qP波相速度对弹性模量参数和Thomsen参数的偏微分不同,所以可以分别反演弹性模量参数和Thomsen参数.数值模拟结果表明:利用qP反射波可以反演出TI介质模型的弹性模量参数与Thomsen参数,不同模型的走时迭代反演达到了较好的收敛效果,与各向同性介质走时反演结果相比较,各向异性介质走时反演结果具有较好的识别能力.

High resolution facies architecture and digital outcrop modeling of the Sandakan formation sandstone reservoir, Borneo:Implications for reservoir characterization and flow simulation

Advances in photogrammetry have eased the acquisition of high-resolution digital information from outcrops, enabling faster, non-destructive data capturing and improved reservoir modeling. Geocellular models for flow dynamics with in the virtual outcrop in siliciclastic deposits at different sets of sandstone facies architecture remain, however, a challenge. Digital maps of bedding, lithological contrast, spatial-temporal variations of bedding and permeability characteristics make it more easy to understand flow tortuosity in a particular architecture. An ability to precisely model these properties can improve reservoir characterization and flow modeling at different scales. Here we demonstrate the construction of realistic 2 D sandstone facies based models for a pragmatic simulation of flow dynamics using a combination of digital point clouds dataset acquired from LiDAR and field investigation of the Sandakan Formation, Sabah, Borneo.Additionally, we present methods for enhancing the accuracy of outcrop digital datasets for producing high resolution flow simulation. A well-exposed outcrop from the Sandakan Formation, Sabah, northwest Borneo having a lateral extent of 750 m was chosen in order to implement our research approach. Sandstone facies and its connectivity are well constrained by outcrop observations, data from air-permeability measurements, bilinear interpolation of permeability, grid construction and water vector analysis for flow dynamics.These proportions were then enumerated in terms of static digital outcrop model(DOM) and facies model based on sandstone facies bedding characteristics. Flow simulation of water vector analysis through each of the four sandstone facies types show persistent spatial correlation of permeability that align with either cross-bedded orientation or straight with more dispersion high quality sandstone(porosity 21.25%-41.2%and permeability 1265.20-5986.25 mD) and moderate quality sandstone(porosity 10.44%-28.75% and permeability 21.44-1023.33 mD). Whereas, in more heterolithic sandstone(wavy-to flaser-bedded and bioturbated sandstone), lateral variations in permeability show spatially non-correlated patterns over centimeters to tens of meters with mostly of low quality sandstone(porosity 3.4%-12.31% and permeability < 1 mD to 3.21 mD). These variations reflect the lateral juxtaposition in flow dynamics. It has also been resulted that the vertical connectivity and heterogeneities in terms of flow are mostly pragmatic due to the interconnected sandstone rather than the quality of sandstone.

Numerical analysis of the effects of downhole dynamic conditions on formation testing while drilling

Formation testing while drilling is an innovative technique that is replacing conventional pressure testing in which the fluid sampling is conducted in a relatively short time following the drilling. At this time, mud invasion has just started, mudcake has not formed entirely and the formation pressure is not stable. Therefore, it is important to study the influence of the downhole dynamic environment on pressure testing and fluid sampling. This paper applies an oil-water two phase finite element model to study the influence of mudcake quality and mud filtrate invasion on supercharge pressure, pretest and sampling in the reservoirs of different permeability. However, the study is only for the cases with water based mud in the wellbore. The results illustrate that the mudcake quality has a significant influence on the supercharge pressure and fluid sampling, while the level of mud filtrate invasion has a strong impact on pressure testing and sampling. In addition, in-situ formation pressure testing is more difficult in low permeability reservoirs as the mud filtrate invasion is deeper and therefore degrades the quality of fluid sampling. Finally, a field example from an oil field on the Alaskan North Slope is presented to validate the numerical studies of the effects of downhole dynamic conditions on formation testing while drilling.

Astronomical Dating of the Middle Miocene Hanjiang Formation in the Pearl River Mouth Basin,South China Sea

The Hanjiang Formation of Langhian age （middle Miocene） in the Pearl River Mouth Basin （PRMB）, South China Sea consists of deltaic siliciclastic and neritic shelf carbonate rhythmic alternations, which form one of the potential reservoirs of the basin. To improve stratigraphic resolutions for hydrocarbon prospecting and exploration in the basin, the present study undertakes spectral analysis of high-resolution natural gamma-ray （NGR） well-logging record to determine the dominant frequency components and test whether Milankovitch orbital signals are recorded in rhythmic successions. Analytical results indicate the orbital cycles of precession （~19 ka and ~23 ka）, obliquity （-41 ka）, and eccentricity （~100 ka and --405 ka）, which provide the strong evidence for astronomically driven climate changes in the rhythmic alternation successions. Within biochronological constraint, a high-resolution astronomical timescale was constructed through the astronomical tuning of the NGR record to recent astronomically calculated variation of Earth＇s orbit. The astronomically tuned timescale can be applied to calculate astronomical ages for the geological events and bioevents recognized throughout the period. The first downhole occurrences of foraminifers Globorotalia peripheroronda and Globigerinoides sicanus are dated at 14.546 Ma and 14.919 Ma, respectively, which are slightly different from earlier estimates in the South China Sea. When compared with the global sea-level change chart, the astronomical estimate for the sequences recognized based on microfossil distributions have the same end time but the different initiation time. This is probably due to the local or regional tectonic activities superimposed on eustatic rise which postponed the effect of global sea-level rising. Astronomical timescale also resolves the depositional evolution history for the Langhian Stage （middle Miocene） with a variation that strongly resembles that of Earth＇s orbital eccentricity predicted from 13.65 Ma to 15.97 Ma. We infer that the main factor controlling the variability of the sedimentation rate in the Hanjiang Formation is related to the ^-405-ka-period eccentricity.

Investigation into the effect of silica nanoparticles on the rheological characteristics of water-in-heavy oil emulsions

The effect of silica nanoparticles on the rheological characteristics of water-in-heavy oil emulsions has been investigated.Enhanced oil recovery methods for heavy oil production(most especially,thermal fluid injection)usually result in the formation of water-in-oil(W/O)emulsion.In reality,the emulsion produced also contains some fine solid mineral particles such as silica,which,depending on its quantity,may alter the viscosity and/or rheological properties of the fluid.A series of binary-component emulsions were separately prepared by dispersing silica nanoparticles[phase fraction,βs,=0.5%–5.75%(wt/v)]in heavy oil(S/O suspension)and by dispersing water[water cut,θw=10%–53%(v/v)]in heavy oil(W/O emulsion).Ternary-component emulsions comprising heavy oil,water droplets and suspended silica nanoparticles(S/W/O)were also prepared with similar ranges ofθw andβs.The viscosity was measured at different shear rates(5.1–1021.4 s-1)and temperatures(30–70°C).Both binary-component and ternary-component emulsion systems were observed to exhibit nonNewtonian shear thinning behaviour.The viscosity of the heavy oil and W/O emulsions increased in the presence of silica nanoparticles.The effect was,however,less signifi cant belowβs=2%(wt/v).Moreover,a generalized correlation has been proposed to predict the viscosity of both binary-component and ternary-component emulsions.

Source,depositional environment and maturity levels of some crude oils in southwest Niger Delta,Nigeria

A suite of crude oil samples,that had not been previously characterized geochemically,was collected from two oil fields in the southwest Niger Delta Nigeria.The saturate biomarkers were used to evaluate geochemical characteristics such as depositional environments,sources of organic matter and extent of biodegradation using gas chromatography-flame ionization detector and gas chromatography-mass spectrometry.Distribution of n-alkanes(Pr/Ph,and isoprenoide/n-alkanes ratios),the abundance of hopanes,oleanane skeleton and C27-C29 steranes in the oils indicate that they were formed from mixed sources(marine and terrestrial kerogen) deposited in an oxic paleoenvironment with no particular maturity trend.These parameters also permit the source grouping of the oils into two families.

Organic geochemistry of the Lower Permian Tak Fa Formation in Phetchabun Province,Thailand:implications for its paleoenvironment and hydrocarbon generation potential

The outcrop samples of the Tak Fa Formation(Lower Permian)in Phetchabun Province have been studied to determine their organic geochemical characteristic,depositional paleoenvironment,and hydrocarbon generation potential.The total organic carbon(TOC)values ranging from 1.42 to 4.58 wt%and extractable organic matter values ranging from 76.84 to 197.65 ppm of the Tak Fa Formation were generally low and associated with low S2 values(0.00-0.50 mg HC/g rock)and hydrogen index values in range of 0-32 mg/g TOC,although this could reflect highly thermal maturity and complex tectonic history.Thus,kerogen classification can be based on a nonbiomarker study for these outcrop samples instead.The non-biomarker plot,Pr/n-C17 and Ph/n-C18 from this study indicates that organic matter originally comes from typeⅡ/III kerogen.The samples were also investigated and indicated that the organic matter inputs were derived from mixed marine and terrigenous sources and deposited under suboxic to oxic conditions.The depositional environment of the Tak Fa Formation in this study is interpreted to be an estuarine environment or restricted lagoonal carbonate platforms.This has been achieved from normal alkane and isoprenoids distributions,terpane,and sterane biomarkers.Thus,the Tak Fa Formation is considered to be a hydrocarbon source rock during the time of the deposition.Although the geochemical data in this study indicate that the Tak Fa Formation has experienced high maturation,one or more locations could meet a condition that places this formation to be an active source rock.The approach and concepts presented in this study can be applied to similar evaporite-carbonate deposits in Thailand to find more petroleum plays.

Applications of variogram modeling to electrical resistivity data for the occurrence and distribution of saline groundwater in Domail Plain,northwestern Himalayan fold and thrust belt,Pakistan

This paper studies electrical resistivity dataset acquired for a groundwater study in the Domail Plain in the northwestern Himalayan section of Pakistan. Through a combination of geostatistical analysis,geophysical inversion and visualization techniques,it is possible to re-model and visualize the single dimension resistivity data into 2D and 3D space.The variogram models are utilized to extend the interpretation of the data and to distinguish individual lithologic units and the occurrence of saline water within the subsurface. The resistivity data has been calibrated with the lithological logs taken from the available boreholes. As such the alluvial system of the Domail Plain has formed during episodes of local tectonic activity with fluvial erosion and depositionyielding coarse sediments with high electrical resistivities near to the mountain ranges and finer sediments with medium to low electrical resistivities which tend to settle in the basin center. Thus a change is depositional setting happened from basin lacustrine environment to flash flooding during the Himalayan orogeny. The occurrence of rock salt in the northern mountains has imparted a great influence on the groundwater quality of the study area. The salt is dissolved by water which infiltrates into the subsurface through the water channels. Variogram aided gridding of resistivity data helps to identify the occurrence and distribution of saline water in the subsurface.

Subdomain Chebyshev Spectral Method for 2D and 3D Numerical Differentiations in a Curved Coordinate System

A new numerical approach, called the “subdomain Chebyshev spectral method” is presented for calculation of the spatial derivatives in a curved coordinate system, which may be employed for numerical solutions of partial differential equations defined in a 2D or 3D geological model. The new approach refers to a “strong version” against the “weak version” of the subspace spectral method based on the variational principle or Galerkin’s weighting scheme. We incorporate local nonlinear transformations and global spline interpolations in a curved coordinate system and make the discrete grid exactly matches geometry of the model so that it is achieved to convert the global domain into subdomains and apply Chebyshev points to locally sampling physical quantities and globally computing the spatial derivatives. This new approach not only remains exponential convergence of the standard spectral method in subdomains, but also yields a sparse assembled matrix when applied for the global domain simulations. We conducted 2D and 3D synthetic experiments and compared accuracies of the numerical differentiations with traditional finite difference approaches. The results show that as the points of differentiation vector are larger than five, the subdomain Chebyshev spectral method significantly improve the accuracies of the finite difference approaches.

Integrated and Explicit Boundary Conditions of Electromagnetic Fields at Arbitrary Interfaces between Two Anisotropic Media

This paper derives two new integrated and explicit boundary conditions, named the “explicit?normal version” and “explicit tangential versions” respectively for electromagnetic fields at an arbitrary interface between two anisotropic media. The new versions combine two implicit boundary equations into a single explicit matrix formula and reveal the boundary values linked by a 3 × 3 matrix, which depends on the interface topography and model property tensors. We analytically demonstrate the new versions equivalent to the common implicit boundary conditions and their application to transformation of the boundary values in the boundary integral equations. We also give two synthetic examples that show recovery of the boundary values on a hill and a ridge, and highlight the advantage of the new versions of being a simpler and more straightforward method to compute the electromagnetic boundary values.

Source Rock Evaluation and 1-D Basin Modelling Approach for the Sargelu Formation, Atrush-2 Well, Kurdistan Region-Iraq

The present study focuses on source rock evaluation of the Sargelu Formation by using core chips of rocks collected from well Atrush-2, Duhok, Kurdistan Region-Iraq. The Rock-Eval pyrolysis and vitrinite reflectance were executed. Subsequently, the selected parameters were used for source rock evaluation and 1-D Basin Modelling calibration. The upper part of the formation mainly comprises argillaceous limestone with low content of organic matter (0.64% - 1% TOC). By contrast, the lower part is dominated with shale interval and contains high amounts of TOC values (>4% for 1272 - 1278 m) reveling good to very good quality source rock. Accordingly, good to very good hydrocarbon generation potential is suggested for this formation. Organic matter of the Sargelu Formation contains type II and mixed-type II-III kerogen. The values of Tmax and vitrinite reflectance (Ro%) demonstrate that the formation is thermally mature and in the oil zone. In order to construct a thermal history of the formation and determine the timing of hydrocarbon maturation and generation, the 1-D basin modelling PetroMod 2019.1 was used in this study. Based on the 1-D Basin modelling simulation and its outputs, about 3500 m of overburden have been eroded at the study area. The present-day heat flow was found to be 30 mW/m2. The organic matter of Sargelu Formation entered the early oil zone in 64 Ma and reached the main oil zone ca. 5 Ma. The formation is still in the main oil zone at present-day. In well Atrush-2, the highest rate of oil generation for the Sargelu Formation was in the 8.5 Ma, the onset of oil expulsion from Sargelu Formation was in 50 Ma and the expulsion mass has been reached 0.5 Mtons at present-day.

Reservoir Characterization of the Early Cretaceous Sarmord and Garagu Formations from Atrush-1 and Mangesh-1 Wells, Kurdistan Region, Iraq

Petrophysical properties of the Early Cretaceous Sarmord and Garagu formations from the Atrush and Sarsang Blocks in the Kurdistan Region are studied. These formations are generally composed of limestones and dolomitic limestones interbedded with thin to medium layers of yellowish-gray marl (calcareous mudstone). The current study shows that the average shale volume in the Sarmord and Garage formations is between 16% and 20%. In Atrush-1 Well, the average porosity ratio of the Sarmord and Garagu formations is fair to good (15% and 11%, respectively). However, in Mangesh-1 Well, the porosity value is poor;it is around 4% on average. Generally, most of the hydrocarbons that have been observed within the pore spaces are residual oil type in Atrush-1 Well and movable hydrocarbon type in Mangesh-1 Well. In Atrush-1 Well, out of 362 m thickness of both formations, only 180 m is considered to be a pay zone;whereas, the pay zone is just around 8.0 m thick out of 347 m of the total thickness. According to the calculated porosity values, the Garagu and Sarmord formations are not considered as good reservoirs in the studied wells, with the exception of Atrush-1 Well where the Sarmord Formation has fair potential reservoir characteristics.

Determination of total organic carbon content using Passey's method in coals of the central Kalahari Karoo Basin,Botswana

This paper focuses on determining total organic carbon(TOC)from boreholes in the Kalahari Basin,Botswana,using Passey's method.The Kalahari Karoo basin is one of several basins in southern Africa filled with Late Carboniferous to Jurassic sedimentary strata that host Permian age coal seams.Nine exploration boreholes(wells)drilled in the central Kalahari Karoo basin are used to determine the Total Organic Carbon potential.Vitrinite reflectance(Ro),proximate and ultimate analyses were conducted on cored coal intervals.Passey's DLogR method applied in this study employs resistivity and porosity logs to identify and quantify potential source rocks.Results of Passey's method compared with laboratorymeasured carbon showed that Passey's method effectively identifies coal intervals.In terms of TOC calculations,the method works poorly in coal metamorphosed by dolerite intrusions.The heat affected coal samples had Ro from 0.77% to 5.53% and increased in maturity from primarily maceral controlled to high volatile bituminous and anthracite coal.Results from proximate analysis showed compositional changes in the coal were controlled by proximity to sill intrusion,with a decrease in Fixed Carbon and an increase in ash yield in the contact metamorphism zone(2-12 m from sill).For the unaltered coal that has undergone burial maturation displaying Ro of 0.44%-0.65%,the method works well.In unintruded boreholes,correlations between Carbon and calculated TOC indicate strong relationships.Passey's DLogR method proved to be a suitable method of estimating TOC on coal that has undergone burial maturation.This study has demonstrated that TOC calculated from the sonic log is more reliable in coal not affected by contact metamorphism than TOC calculated from the density log.

Performance evaluation of nanosilica derived from agro-waste as lost circulation agent in water-based mud

Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation.The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks.Loss circulation materials(LCMs)are commonly introduced into the drilling mud to prevent or minimize filtrate loss.This study investigates silica nanoparticle(SNP)derived from rice husk(RH)termed RH-SNP using the wet-milling method as an LCM inwater-based mud(WBM).The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied.Subsequently,the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk.The performance of the developed RH-SNP was compared with the widely applied nutshell.The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%,respectively,and minimized the fluid loss of the WBM by 47% at 80°F.The enhancement is due to the particles ability to spread and interact efficiently with the WBM.With the use of 1 mm and 2 mm simulated fracture for 7 min,the mud loss volume of the base mud reduced by 50%,66.7%,86%,and 90%(for 1 mm)and 40%,65.7%,77.1%,and 80%(for 2 mm)with the inclusion of 0.5 wt%,1.0 wt%,1.5 wt%,and 2.0 wt% of RH-SNP,respectively.Overall,the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell.The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.

Development of new correlations for the oil formation volume factor in oil reservoirs using artificial intelligent white box technique

Oil formation volume factor(OFVF)is considered one of the main parameters required to characterize the crude oil.OFVF is needed in reservoir simulation and prediction of the oil reservoir performance.Existing correlations apply for specific oils and cannot be extended to other oil types.In addition,big errors were obtained when we applied existing correlations to predict the OFVF.There is a massive need to have a global OFVF correlation that can be used for different oils with less error.The objective of this paper is to develop a new empirical correlation for oil formation volume factor(OFVF)prediction using artificial intelligent techniques(AI)such as;artificial neural network(ANN),adaptive neuro-fuzzy inference system(ANFIS),and support vector machine(SVM).For the first time we changed the ANN model to a white box by extracting the weights and the biases from AI models and form a new empirical equation for OFVF prediction.In this paper we present a new empirical correlation extracted from ANN based on 760 experimental data points for different oils with different compositions.The results obtained showed that the ANN model yielded the highest correlation coefficient(0.997)and lowest average absolute error(less than 1%)for OFVF prediction as a function of the specific gravity of gas,the dissolved gas to oil ratio,the oil specific gravity,and the temperature of the reservoir compared with ANFIS and SVM.The developed empirical equation from the ANN model outperformed the previous empirical correlations and AI models for OFVF prediction.It can be used to predict the OFVF with a high accuracy.