A New Method for Calculating the Cementation Exponent of Triple-Porosity Media Reservoirs

The value of a cementation exponent, usually obtained by rock and electricity experiments, significantly affects the calculation of water saturation, thickness of the hydrocarbon reservoir, and recovery rate. The determination of the cementation exponent for porous-media reservoirs has been a challenge because of the limited core sampling. A new method was proposed to determine the value of cementation exponent for complex triple-porosity media reservoirs in the work. Firstly, the work discussed the effects of fractures and nonconnected vugs on the cementation exponent of the reservoir as well as the calculation method of the cementation exponent of the dual-porosity media reservoir. Then, a new model for calculating the cementation exponent of triple-porosity media reservoirs was derived by combining the Maxwell-Garnett theory and series-parallel theory, which matched with the real physical-experiment data of rocks. The results showed that the fractures decreased the cementation exponent of the reservoir but the vugs increased. The mixture of matrix pores, fractures, and vugs made the value of the cementation exponent of the triple-porosity media reservoir vary around 2.0. The conductivity of the triple-porosity media reservoir was the external macroscopic expression of the microscopic conductive network. The new calculation model of the cementation exponent proposed in the work could reasonably predict the cementation exponent of the strongly inhomogeneous triple-porosity media reservoir.

Classification the Shahrekord plain to find the suitable sites for artificial recharge using analytic hierarchy processesz

During recent years, the shortage of surface water resources is a serious problem facing to the Chaharmahal and Bakhtiari province. Hence, the groundwater exploration should be limited for developing the new water resources such as artificial recharge. One of the main step of this process is locating suitable sites for constructing the artificial recharge structure. The objective of this study is determination of effective parameters on artificial recharge structure construction in Shahrekord plain to propose the best sites. The eight parameters affecting the artificial recharge structure construction are including permeability, hydraulic conductivity, precipitation, land slope, nitrate concentration, salinity, saturated and unsaturated thickness of aquifer. For this purpose, ArcGIS10.3 software for the analytic hierarchy processes (AHP) and Expert Choice 11 software for prioritize suggested areas were used. Weight permeability 0.28 was in the first preference, hydraulic conductivity 0.23 in the second preference, saturation thickness of aquifer 0.17 in the third preference. Permeability, hydraulic conductivity and saturation thickness of aquifer are considered as the main parameters with the weight of 0.28, 0.23 and 0.17, respectively. Moreover, the weights of precipitation, land slope, and unsaturated thickness were obtained o.11, 0.08, and 0.06, respectively. The results show that about 0.089 percent of the study area are suitable for artificial recharge structure construction.

Polarization screening-induced epitaxial growth and interfacial magnetism of BiFeO3/PbTiO3 nanoplates

Single-crystal BiFeO3/PbTiO3 nanoplates have been synthesized via a hydrothermal method, where BFO films selectively grew on the negative polar surface of PTO with a saturation thickness of about 18–20 nm and a room-temperature ferromagnetism.

The effect of the diameter of the detector collimator on saturation thickness in gamma scattering measurement

The effect of the diameter of the detector collimator on the saturation thickness in gamma-scattering measurements is studied using the spectrum of singly scattering. Geometric arrangement of gamma-scattering measurement includes: a gamma-ray collimated beam with the energy of 662 keV emitted from 137Cs source is irradiated on a rectangular aluminium target with incident angle of 90o, and detector NaI(Tl) 5.1cmx5.1cm with collimator is used to record the scatterd gamma rays at scattered angle of 120°. The experimental measurements are carried out to obtain scattered spectra with various target thickness and diameter of detector collimator. The profile of the singly scattering and multiply scattering in the scattered spectra are determined by a spectrum processing technique based on the least squares fitting. The experimental results showed that the saturation thickness of the counts of singly scattering increases with increasing the window diameter of the detector collimator. These results will support for the non-destructive testing research of application of gamma-scattering method to determine the thickness or the defect of the sample.