Sedimentary and environmental conditions of Al-Rassafeh Badyieh (Area-2), Syria through aerial gamma ray spectrometry and multifractal techniques.

The interpretation of aerial gamma ray spectrometry in term of geological and environmental analysis is undertaken herein through applying a specific methodology including different radioactive and statistical techniques for characterizing the sedimentary and environmental conditions of the Al-Rassafeh Badyieh (Area-2), Syria. The radioactive technique uses the uranium favorability index (UI) and alteration(F) parameters, that are evaluated through analyzing the relationships between eU, eTh, K and their ratios (eTh/eU, eU/eK, and eTh/eK) for the nine scored lithological units already determined in the study area. The statistical technique applies the non linear multifractal approach with the concentration-number model (C-N) and log-log graphs to differentiate between different radioactive ranges of UI and F parameters. The radioactive element re-distribution, the favorability as regards uranium potentiality, and the degree of uranium remobilization are separately estimated and documented for the nine scored lithological units. Those units show a limited uranium remobilization and redistribution. The sedimentary and environmental conditions of the Area-2 are clarified through analyzing the eTh/eU ratio, where marine and continental environments are indicated in the study region.

Exploration of probable hydrocarbon micro-seepage accumulations in Area-3, Northern Palmyrides, central Syria by using airborne gamma-ray spectrometric technique.

Aerial gamma-ray spectrometry technique is used herein as an indirect approach for petroleum prospecting to investigate possible hydrocarbon stratigraphic and structural traps of Area-3, Northern Palmyrides, Syria. This indirect approach is based on the thorium Th normalization technique, oriented towards suppressing the influence of the regional geological signatures. The use of the thorium normalization technique in the study Area-3 allows to detect new subtle micro-seepage anomalous patterns. The detected micro-seepage occurrences are characterized by both low residual potassium values termed as KD (%) and high uranium residual values in relation to potassium, termed as DRAD (%) values. DRAD (%) results from the subtraction of potassium from uranium residual values. Eight probable zones are identified and mapped over the study area grace to the application of the thorium normalization technique, that might indicate a prospective possibility for feasible subsurface hydrocarbon accumulations and oil-bearing pay zones at Area-3.

Radioactive heat production of Syrian territory.

Gamma-ray spectrometry is applied to estimate equivalent uranium (eU), equivalent thorium (eTh), and K% of 748 rock samples collected from Syrian territory. The spectrometry results are used to evaluate and map the radioactive heat production (HP) of Syria. A new approach involving the multifractal technique with the concentration-number model (CN) and log-log plots was originally proposed and hence applied in this paper to map the distribution of uranium concentration and HP of Syria. This approach helps us to differentiate different eU and HP ranges related to different litho-types. The advantages of proposing and applying the fractal technique are that the boundaries of the distinguished radioactive ranges of eU and HP coincide well with the lithological boundaries, which gives this technique superiority over other traditional statistical methods. The fractal CN model with the use of log-log plots proves its efficacy in differentiating between several eU and HP populations that are related directly to the geology of Syrian territory. The fractal model shows four threshold break points corresponding to uranium concentrations of 3.1, 7.38, 16.6, and 28.8 ppm and an HP of 0.715, 1.86, 3.63, and 6.26 µW/m3, respectively. The highest HP ranges are mainly related to the phosphatic deposits, characterized by the highest uranium content.

Heat production estimation by using natural gamma-ray well-logging technique in phosphatic khneifis deposit in Syria.

Natural gamma-ray (GR) well-logging technique is used to estimate the radioactive heat production (HP) parameter as a function of depth, in the phosphatic Khneifis deposit in Palmyrides region in Syria. Seven available drilled wells with their natural GR records are used to characterize and estimate the HP magnitude in the study region. The analysis of 2660 measured points in those wells shows that HP varies between a minimum of 0 and a maximum of 7.97 µw/m3, with an average of 1.33 µw/m3 and a standard deviation of 1.68 µw/m3. Multi-fractal approach with the use of concentration-number (C-N) model and log-log plots is originally proposed and used as a new approach for characterizing the HP variations and isolating different HP populations in the study region. The high HP ranges are mainly related to the phosphatic layers, relatively enriched by uranium concentrations, comparing with their surroundings.

Estimation and mapping of radioactive heat production by aerial spectrometric gamma and fractal modeling techniques in the Syrian desert (Area-1), Syria.

Radioactive heat production (HP) in the Syrian desert (Area-1) is estimated by using the available data of aerial spectrometric gamma technique. The HP is separately well characterized for 10 geological units, which are identified on the already established Area-1 scored map. Fractal technique combined with concentration-number (C-N) model and log-log graphs is used to map total radioactivity, equivalent uranium, and HP in Area-1. The HP in Area-1 varies between a minimum of 0 and a maximum of 7.23 µw/m3, with an average of 0.584 µw/m3 and a standard deviation of 0.341 µw/m3. The lithological phosphatic units A, B, C, and D are characterized by a higher HP than their surrounding units, because of their richness in uranium concentrations.

Multifractal approach for delineating uranium anomalies related to phosphatic deposits in Area-3, Northern Palmyrides, Syria.

Multifractal Concentration-Number (C-N) modeling approach has been developed and applied to Airborne Gamma Spectrometry (AGS) data related to Area-3, Northern Palmyrides, Syria. The application of the multifractal approach basically aimed at separating uranium anomalies from background. The AGS technique has been applied for uranium exploration in Syria, where four radioactive parameters were recorded, T.C, eU, eTh, and K%. Log-log plots practiced on those radioactive variables indicate the presence of different uranium anomaly ranges. Those radioactive ranges have been verified and controlled by both geology field and surface spectrometric gamma sample rocks analysis. The area range of 5.37-13.20 eU includes uranium concentration more than 120 ppm, The area range of 2.95-5.37 eU includes uranium concentration of 50 ppm, and the area range of 1.40-2.95 eU includes uranium concentration of 7 ppm. Positive correlation has been consequently found between radioactive anomalous eU ranges and uranium concentrations. Such correlation indicates the importance of multi fractal approach to be extensively used as a fractal analysis-smart sampling tool in phosphate and uranium prospecting programs, where a positive correlation between phosphate content, radioactivity and uranium concentration exist.

Fractal theory modeling for interpreting nuclear and electrical well logging data and establishing lithological cross section in basaltic environment (case study from Southern Syria).

Fractal theory modeling technique is newly proposed in this research for interpreting the combination of nuclear well logging, including natural gamma ray, density and neutron-porosity, and the electrical well logging of long and short normal, for establishing the lithological cross section in basaltic environments. The logging data of Kodana well, localized in Southern Syria are used for testing and applying the proposed technique. The established cross section clearly shows the distribution and the identification of four kinds of basalt which are hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products, clay. The concentration- Number (C-N) fractal modeling technique is successfully applied on the Kodana well logging data in southern Syria, and can be used efficiently when several wells with much well logging data with a high number of variables are required to be interpreted.

Erratum to: Lessening the adverse effect of the semivariogram model selection on an interpolative survey using kriging technique.

[This corrects the article DOI: 10.1186/s40064-016-2142-4.].

Lessening the adverse effect of the semivariogram model selection on an interpolative survey using kriging technique.

OBJECTIVE: Many parameters in environmental, scientific and human sciences investigations need to be interpolated. Geostatistics, with its structural analysis step, is widely used for this purpose. This precious step that evaluates data correlation and dependency is performed thanks to semivariogram. However, an incorrect choice of a semivariogram model can skew all the prediction results. The main objectives of this paper are (1) to simply illustrate the influence of the choice of an inappropriate semivariogram model and (2) to show how a best-fitted model can be selected. This may lessen the adverse effect of the semivariogram model selection on an interpolation survey using kriging technique. METHODS: The influence of the semivariogram model selection is highlighted and illustrated by thematic maps drawn using four different models (Gaussian, magnetic, spherical and exponential). Then, a guideline to select the most suitable model, using mean error (ME), mean square error (MSE), root mean square error (RMSE), average standard error (ASE), and root mean square standardized error (RMSSE), is proposed. RESULTS: The choice of a semivariogram model seriously influences the results of a kriging survey at both endpoints and amplitude of the range of the estimated values. However, the direction of variation of the interpolated values is independent of the semivariogram model: different semivariogram models (with the same characteristics) produce different thematic maps but, the areas of minimum and maximum values remain unchanged. Yet, the suitable model can be selected by means of ME, MSE, RMSE, ASE and RMSSE. CONCLUSION: The present article illustrates how the use of an inappropriate semivariogram model can seriously distort the results of an evaluation, assessment or prediction survey. To avoid such an inconveniency, a methodical approach based on the computation and analysis of ME, RMSE, ASE, RMSSE and MSE is proposed.

Statistical factor analysis technique for characterizing basalt through interpreting nuclear and electrical well logging data (case study from Southern Syria).

Factor analysis technique is proposed in this research for interpreting the combination of nuclear well logging, including natural gamma ray, density and neutron-porosity, and the electrical well logging of long and short normal, in order to characterize the large extended basaltic areas in southern Syria. Kodana well logging data are used for testing and applying the proposed technique. The four resulting score logs enable to establish the lithological score cross-section of the studied well. The established cross-section clearly shows the distribution and the identification of four kinds of basalt which are hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products, clay. The factor analysis technique is successfully applied on the Kodana well logging data in southern Syria, and can be used efficiently when several wells and huge well logging data with high number of variables are required to be interpreted.

Basalt characterization by means of nuclear and electrical well logging techniques. Case study from Southern Syria.

Nuclear well logging, including natural gamma ray, density, and neutron-porosity techniques are used with electrical well logging of long and short normal techniques to characterize the basaltic areas largely extended in Southern Syria. Statistical analysis approach with the threshold concept has been adapted for such characterization, where four kinds of basalt have been identified: very hard basalt, hard basalt, fractured basalt, and basalt alteration products. The spectrometric gamma technique has also been applied on the retrieved rock samples in order to determine the radioactive content (eU, eTh, and K%) of the basaltic section in the study area. No radioactive anomalies have been detected, the radioactive values are normal and in the expected range.

Optimization of low activity spectrometric gamma-gamma probes for ash determination in coal stockpiles.

A stockpile probe based on backscattered gamma-gamma-ray technique was tested for the determination of coal ash. A centralized tool employing a gamma-ray source of very low radioactivity (1.85 MBq) was used. This logging tool was tested using 137Cs and 133 Ba sources with a 37 mm (diameter) by 75 mm NaI (TI) scintillation detector. Ten source-detector configurations were analyzed using 137Cs, and another nine source-detector configurations are analyzed, using 133Ba source, both for four geophysical models, having a borehole diameter of 90 mm. Regression analysis on the laboratory logging data for each studied configuration was carried out in order to establish calibration equations for ash prediction. The optimum configuration for the logging stockpile probe using 137Cs source was determined to be 80 mm source to detector spacing, and 80 mm iron thickness shielding. This configuration gives the best results for ash prediction. The root mean square (rms) deviation for ash is 1.52%. The optimum configuration for the logging stockpile probe using 133 Ba source is determined to be 85 mm source to detector spacing, and 50mm iron thickness shielding. This configuration gives the best results for ash prediction, where the rms deviation for ash is 1.47%.