Fractal study on fault system of Carboniferous in Junggar Basin based on GIS
Fault system is a significant evidence of tectonic movement during crust tectonic evolution and may play an more important role in oil-gas accumulation process than other tectonic types in sedimentary basin. Carboniferous surface faults in Junggar Basin developed well and varied in size and distribution. There are about 200 faults in Carboniferous, and 187 of them are thrust faults. Chaos-fractals theories have been widely investigated and great progress has been made in the past three decades. One of the important conception-fractal dimension had become a powerful tool for describing non-linearity dynamical system characteristic. The clustered objects in nature are often fractal and fault system distribution in space is inhomogeneous, always occurs in groups, so we can describe spatial distribution of faults from the point of fractal dimension. Fractal dimension of fault system is a comprehensive factor associated with fault number, size, combination modes and dynamics mechanism, so it can evaluate the complexity of fault system quantitatively. The relationship between fault system and oil-gas accumulation is a focus and difficulty problem in petroleum geology, and fractal dimension is a new tool for describing fault distribution and predicting potential areas of hydrocarbon resources. Geographic Information System (GIS) is a kind of technological system collecting, storing, managing, computing, analyzing, displaying and describing the geospatial information supported by computer software and hardware. In the last 15–20 years, GIS have been increasingly used to address a wide variety of geoscience problems. Weights-of-evidence models use the theory of conditional probability to quantify spatial association between fractal dimension and oil-gas accumulation. The weights of evidence are combined with the prior probability of occurrence of oil-gas accumulation using Bayes'rule in a loglinear form under an assumption of conditional independence of the dimension maps to derive posterior probability of occurrence of oil-gas accumulation. In this paper, we first vectorize the fault system in Carboniferous of Junggar Basin in GIS software and store it as polyline layer in Geodatabase of GIS to manage and analyze, then calculate the fractal dimension of three types which are box dimension, information dimension and cumulative length dimension using spatial functions of GIS, in the last use weights-of-evidence model to calculate the correlation coefficients in GIS environment between oil-gas accumulation and three types of fractal dimension in order to quantity the importance of fault system.
Quantitative fracture prediction from seismic data
ABSTRACT This paper presents results obtained from an area located east of Bremen, Germany, where gas is produced from a deep Rotliegend sandstone reservoir. Faults, fractures and associated deformation bands at reservoir depth have an important influence on the productivity of the gas field as fractures are cemented and tight and may act as permeability barriers. This contribution comprises the development of new coherency tools to better image sub-seismic faults and lineaments from seismic data, and the development of fracture attributes in order to quantify fracturation and its areal distribution. The fractal behaviour of faults was used to establish a relationship between coherency processed seismic data and borehole images at log scale. The ‘fractal dimension’ (FD) of the length of a fault population can be interpreted as a characteristic parameter describing local geology in terms of fracturation. Calculating FD for each point of a seismic grid yields an areal distribution of this value. Correlating seismic-derived FD values and fracture populations derived from borehole images defined a linear relationship which can be used to forecast the distribution of sub-seismic fractures and deformation from seismic data.
Influence of inducers and inhibitors on the metabolism in vitro and neurochemical effects in vivo of MDMA.
(S)-(+)- and (R)-(-)-3,4-methylenedioxymethamphetamine (MDMA) were metabolized in vitro by rat liver microsomes via N-demethylation to 3,4-methylenedioxyamphetamine (MDA). Whereas no difference was found in the biotransformation of the two enantiomers in the male rat or in the phenobarbital (PB) treated animals of either sex, more than twice as much MDA was formed from (S)-(+)- than from (R)-(-)-MDMA in the untreated female rat. Although 3-methylcholanthrene (3MC) pretreated rat liver microsomes were less active than those from the untreated rats of the same sex, they formed more MDA from (+)- than from (-)-MDMA. The enantioselective metabolism thus appears to be associated with the relative abundance of individual cytochrome P-450 isozymes. (S)-(+)- and (R)-(-)-MDMA.HCl (20 mg/kg) were about equipotent in depleting serotonin (5-HT) levels in the frontal cortex at 3 hrs and 1 wk following oral administration to female rats. Pretreatment of rats with SKF-525A attenuated and that with PB enhanced the 5-HT depleting potential of either isomer at 3 hrs. The 5-HT depleting potency of (+)-MDMA was significantly greater than that of its (-)-antipode at 3 hr in PB pretreated, but not in SKF-525A pretreated animals. The results suggest that the neurochemical effects of MDMA are caused by the formation of an active metabolite in vivo, and since both enantiomers were N-demethylated in vitro to approximately the same extent by PB pretreated rat liver microsomes, the active metabolite may be other than MDA.