Study on Transpiration and Stomatal Conductance Characteristics of C3 and C4 Plant

The transpiration experiment was done under greenhouse conditions with a C3 plant sweet pepper （Capsicum annuum Linn.） and two C4 plants, sorghum （Sorghum bicolor L.Moench） and maize （Zea mays Linn.）. Three species were irrigated with three different water treatment levels of 100%, 66% and 33% which gave a comparison of tolerance and adaptation to irrigation and two different levels of water stress. The measurements of transpiration rate and stomatal conductance were done between 8.00 a.m. and 16.00 p.m. with measurements about each 1.5 h with an infrared gas analyzer. The results showed that Z. mays probably due to a higher leaf area had very low values and was significantly different （LSD pairwise comparison） from C. annuum and S. bicolor. The hypotheses that C4 plants and C3 plants have different transpiration rates and stomatal conductance could not be shown with the results. However, the hypotheses that for the same species, the highest values in transpiration rate and stomatal conductance were with the 100% irrigation treatment and the lowest values were with the 33% irrigation treatment could be accepted due to the results of this trial.

Method for predicting economic peak yield for a single well of coalbed methane

The development of coalbed methane (CBM) in China poses great difficulties because of high investments, low produc- tion and high risks. So a study of the economic effect of a single well at its preliminary stage is helpful for commercial exploitation of CBM. Affected by wellbore flow pressure, initial reservoir pressure, relative permeability, Langmuir pressure and other factors, the trend of declining production of a single CBM well agrees, by and large, with a hyperbolic pattern of decline. Based on Arps’s equation, nearly 200 wells production with different peak yields and initial rates of were simulated. Given the present cost of drill- ing, gas production and engineering on the ground, the gross investment for the development of a single coalbed methane well was estimated for the Fanzhuang block in central China. Considering the current industrial policies for CBM, we established an eco- nomic assessment model and analyzed economic peaks. The results show the economic benefits with or without government subsi- dies at different peak yields of a single CBM well. The results of the evaluation can be directly applied in the Fanzhuang block. The evaluation method, formulated in our study, can be used to other areas with similar conditions.

Magnetotelluric data inversion with seismic data constraint

In the paper we present a new method to invert the interior structure in the basement or ancient hidden hill by using magnetotelluric (MT) data with seismic data constraint. We first obtain the thickness and resistivity of each layer above the basement or buried hill by the inversion of seismic and log data and create a geoelectrical model for the layers above the basement or hidden hill. Then with the reference to the inversion of 1D MT data, a geoelectrical model for the layers below the basement or hidden hill is created. On the basis of the above initial model, we present an effective and practical forward method, i.e., a model-matched approach to conduct forward inversion arithmetic. Finally, by the method of conjugate gradient iteration, a forward and backward iterative calculation is made. Taking No. 618 profile of Shengli Oil Field as an example, we have found out that the tectonic information that is unreflective in the seismic data below the basement is better reflected in the inversion result.

A new method of migration imaging for MT data

Based on the study on electromagnetic field migration by Zhdanov, we have proposed an improved method for the weak points in the research. Firstly, the initial background resistivity should be determined by using 1-D inversion results. Then in the process of continuation, the results are corrected and calculated layer by layer by the iteration method, so that more exact resistivity can be obtained. Secondly, an improved algorithm for finite-difference equation is studied. According to the property of electromagnetic migration field, the algorithm is designed by means of grids varying with geometric progression in the longitudinal direction. Being improved by the techniques mentioned above, better results are obtained by the new method, which has been verified by both the theory model and practical data.

Sedimentary microfacies of the H8 member in the Su14 3D seismic test area

The distribution of sedimentary microfacies in the eighth member of the Shihezi formation（the H8 member） in the Sul4 3D seismic test area was investigated.A Support Vector Machine（SVM） model was introduced for the first time as a way of predicting sandstone thickness in the study area.The model was constructed by analysis and optimization of measured seismic attributes.The distribution of the sedimentary microfacies in the study area was determined from predicted sandstone thickness and an analysis of sedimentary characteristics of the area.The results indicate that sandstone thickness predictions in the study area using an SVM method are good.The distribution of the sedimentary microfacies in the study area has been depicted at a fine scale.

Formation and evolution of the Chinese marine basins

There are plenty of petroleum resources in the Chinese marine basins, which will be the potential exploration regions of petroleum in the 21st century. The formation and evolution of the Chinese marine basins have mainly undergone two major tectonic epochs and five tectonic evolution stages. The first major tectonic epoch is the early Paleozoic plate divergence and drifting epoch during which the marine basins were formed, and the second one is the late Paleozoic plate convergence and collision epoch during which the pre-existent marine basins were superimposed and modified. The five tectonic evolution stages include: ① the drifting of micro-continental plates in Oceans and the formation of marine basins mainly filled with carbonate rocks during Proterozoic-Middle Carboniferous; ② the northward collage and convergence of continental plates and the development of the paralic sedimentary basins during Late Carboniferous-Middle Triassic; ③ the tectonically stabilized stage after the plate collage and the superimposition of lacustrine basins controlled by the inland subsidence during Late Triassic-Early Cretaceous; ④ the stage of the inland deformation and successive deep burial, uplifting, erosion or breakage of marine basins influenced by the plate tectonic activities of Neo-Tethys Ocean and the West Pacific developed in Late Cretaceous-Paleocene; ⑤ the stage of the foreland compression and basin-range coupling in the margin of the marine basins caused by the collision between India and Eurasia Plates and its long-distance effect since Neocene. The process of the tectonic evolution has controlled the petroleum geologic characteristics of Chinese marine basins, and a material foundation for the formation of oil and gas reservoirs has been built up via the formation of Paleozoic ma- rine basins, and the Mesozoic-Cenozoic tectonic superimposition and modification have controlled the key conditions of hydrocarbon accumulation and preservation. From the Late Proterozoic to the Early Paleozoic, the stratigraphic sequences of the deep-water shale and continental margin marine carbonate rocks in the ancient plate floating in the oceans have developed high-quality marine source rocks and reef-shoal reservoirs. In Late Paleozoic, the crustal plates converged and uplifted into continent and the paleouplifts in the intra-cratonic basins have become good reservoirs of hydrocarbon migration and accumulation, and paralic coal beds have formed regional cap rocks. The Mesozoic-Cenozoic tectonic stability has determined the preservation condition of the Paleozoic marine basins. The marine basins have Precambrian crystal basement, the tectonic activities are relatively stable and the basin modification is relatively faint, and the ancient reservoirs are fit for preservation, such as the Tarim Basin, Sichuan Basin and Ordos Basin. They are all potential regions for marine oil and gas to be explored.