With the soaring price of world energy and the serious mine disasters caused by gas explosion, under the emission reduction demand of green house gas (GHG), the development of coalbed methane (CBM) has been paid more attention to increasingly both at home and abroad. Influenced by technologies, funds, and policies, the CBM production reached 49.5 billion cubic meters in the U.S. in 2007. China is abundant in CBM resources. However, the CBM industry development is limited because of poor exploration and development technologies. Starting from the history of CBM exploration and development technologies, this paper discusses the current theories, technologies, and equipment and the existing problems both at home and abroad, pointing out the development trend of all technologies, and giving some suggestions. They all provide microscopic plans and decision evidences for the development of CBM industry in critical stages.

Research on the controlling factors of fault reservoirs enrichment shows that the distribution of major fault reservoirs is determined by source faults, while the main oil layers are controlled by both the active periods of faults and the regional caps. Three types of distribution models of fault reservoirs are summed up in this paper. In the faulted anticlinal zone in the middle of the depression, fault reservoirs are mainly distributed in partial anticlines and faulted nose structures. In the gentle slope zone, they are mainly distributed in nose structures. In the abrupt slope zone, they are mainly distributed in fault terrace zones and rolling anticlines. The rolling exploration evaluation of complex faulted reservoirs can be summarized as the establishment of five models, i.e., the strata model, the structure model, the formation model, the fluids model, and the reservoir model. New discoveries in rolling exploration may be made, based on the improvement of recognition.

Based on the basic principles and research methods of sequence stratigraphy, a precious sequence stratigraphic analysis of the Triassic Lower Karamay Formation in Ba'er Zone of Northwestern Junggar Basin is made, using outcrops, drilling, logging, and seismic data thoroughly. The sequence stratigraphic framework of the studied area and its corresponding development model are established. The Lower Karamay Formation can be divided into one third-order sequence and two system tracts, namely, a transgressive system tract and regressive system tract. Generally the thickness of sequence and system tracts with local variation are stable. The main sedimentary facies are braided river, braided river delta, lacustrine, subfacies and mocrofacies. The sequence stratigraphic model of the zone is the one that can not define the first flooding surface, which belongs to the depression basin.

The uplift and erosion of strata is ubiquitous in sedimentary basins. Restoration of the exact thickness of eroded strata is very important to rebuild the primary sedimentary and structural evolution history, the geothermal history, the history of hydrocarbon generation, expulsion, migration, and accumulation, and also to evaluate the potential of oil and gas resources accurately. Based on structural evolution research in the Northeast Depression of northern South Yellow Sea Basin, according to the practical geological conditions and data, the methods of variance ratio on thickness of reference layers and sedimentary rate are applied to eroded thickness restoration of Eocene Dainan Formation and Sanduo Formation in Northeast Depression. The final result shows that the Sanduo structural movement that happened at the last stage of Eocene leads to the intense erosion of the strata of Eocene Dainan Formation and Sanduo Formation, as well as the two formations above mentioned indicate distinct characteristics in different structural zones of Northeast Depression

To recognize the break zone exactly is critical to establish the distribution model, the sequence constitution pattern, and the sequence development boundary of lower system tracts in terrestrial rift basins. It is also the basis for the exact prediction of subtle lithologic traps and subtle oil and gas reservoirs. It is indicated by the research on Nanyang Depression that the break zone on the northern slope is developed as a result of the slip of normal faults of the southern depression on the negative plane. On the basis of the sequence stratigraphic framework of the break zone, the characteristics of the gentle slope-break zone of the depression and its controlling factors are summed up. Combining the theory of break zones and the exploration practice in Nanyang Depression, the model predicting favorable reservoir bodies distribution is built, which is of great significance to the oil and gas exploration henceforth.

The source rock characteristics, the reservoir types, the caps characteristics, the generation-reservoir-cap assemblages, the oil and gas traps types and distribution laws of the sag are discussed, based on the geological data, the geophysical data, the drilling data, and satellite image data of the Baolegentaohai sag in the Erlian Basin. The exploration and development trend is suggested.

The unique desorption/adsorption mechanism of coalbed methane (CBM) determines that its evaluation is different from the conventional natural gas. This paper attempts to combine the criteria of CBM, coal, and natural gas reserves organically, elaborating the fundamental requirement on evaluation of proved reserves in CBM Resources and Reserves, discussing how to determine evaluating conditions, unit division, and evaluating methods, and how to select reserves evaluating parameters. Based on the predicting method of CBM recovery ratio and the submitted reserves report, a view is suggested that the CBM recovery ratio is evaluated synthetically and different gas reserves are placed with different values. As a result, the reserves evaluating results get more rational and scientific

The coherence analytical technology is used by many researchers to study complex geological structures and fault development zones, and to predict fracture development zones. However, traditional technologies have some limits. The basic principles and key parameters selecting methods of a more advanced high resolution coherent volume analytical technology based on the eigenvalue are studied. Through the attribute calculation of the high resolution coherent volume based on eigenvalue, some important characteristic parameters related to faults, micro-fractures, lithology, and lithologic facies are obtained. They can be used to describe the slight change of geologic production more clearly, providing a powerful technological tool for geologists to study the structural deformation and lithologic variation. Both the traditional coherence analytical technology and the high resolution one are applied to the practical seismic data processing in Chepaizi area of northwestern Jungger Basin. It is shown that the high resolution coherence analytical technology can be used to detect faults and fractures and good application results are achieved.

The lithology of the Xinglongtai buried hill is identified, based on combining the core analysis technology with the logging crossplot technology. By using the well testing and early production test data, the criteria of identifying reservoirs in metamorphic rock buried hills are established. The logging data standardization method of the metamorphic rock buried hill is explored during study. Using conventional logging data and image logging data, the porosity of the metamorphic rock buried hill is evaluated

The portfolio optimizing technology is a hot spot of the international petroleum study, while the exploration portfolio system is an important tool to support the implementation of exploration strategies and the planning of exploration allocation of the company. Based on systematic research on portfolio optimization methods, an exploration portfolio system featuring in advanced technologies and perfect function is developed in CNOOC. The system can be used for the economic evaluation of exploration targets, the single-target and multischeme selection, the multi-target synthetic queuing, the zone economic evaluation, and the optimization of exploration portfolio. It helps to realize the integration of the economic evaluation of exploration targets and zones and the research of portfolio and to enrich them. And the evaluating process can be more applied to offshore exploration and development. The system can be widely used in the evaluation of exploration targets, the annual combination of drilling targets, the seasonal drilling allocation, and the rolling planning.

During exploration and production, the discovery of oil and gas reserves can be considered to be the result of 2D seismic work, 3D seismic work, and well exploration. When the contribution of exploration to reserves discovery is measured, an oilfield in China is selected as a case. A regressive model is established, taking the proved reserves as dependent variables and the exploration obligation as independent variables. Besides, the other regressive model is established, taking the exploration obligation as dependent variables and the 2D and 3D seismic work as independent variables. On the basis of the regression coefficient obtaining from the two models, the contribution rate of 2D and 3D seismic work is measured and calculated comprehensively. The contribution rate of exploration obligation to reserves discovery can be seen as the basis for making investment decisions and deploying work in oilfields

Reservoir B is the major oil production zone of Kuman Oilfield in Volga Basin, of which the oil in place accounts for 48.5% of the total. Research on the sedimentary features and heterogeneity of the reservoir is conducted, using the drilling, logging, and core data. Results show that the reservoir is tide delta and tide-delta sedimentary facies. The major oil layer (C1- Ⅴ and C1- Ⅵ) is dominated by dune ridges, while the non-major one is dominated by tidal channels, mudflat facies, and sandflat facies. The reservoir permeability variation coefficients range from 0.42 to 1.62, and the mutation coefficients are between 1.87 and 6.69. The permeability ratio is higher. The interlayer heterogeneity and the inner heterogeneity are strong, while the plane heterogeneity is weaker. Comprehensive evaluation shows that the C1- Ⅴ and C1- Ⅵ layers feature in stable plane distribution and good connectivity, and they are favorable for development. The C1- Ⅳ, C1- Ⅲ, and C1- Ⅱ layers feature in severe heterogeneity, small petroliferous area, and thin oil layers, and they are unfavorable for development.

There are six hydrocarbon basins in Libya, in which four are Paleozoic hydrocarbon basins, i.e., the Ghadamis Basin, the Murzuq Basin, the Kufra Basin, and the Cyrenaica Basin. The proved reserves of the basins account for 9% of the total in the whole country. Other reserves centralize in Mesozoic and Cenozoic basins. Based on the study of the exploration history of the oilfields and basins with hydrocarbon discoveries, three factors influencing Paleozoic hydrocarbon discoveries are recognized, namely, the petroleum geology conditions, the exploration degree, the world situation and national policies. The petroleum geology condition is the most critical one. Ghadamis and Murzuq basins have favorable petroleum geology conditions among the four basins. In recent years, the relationship between Libya and U. S. is much better than before and the national policies are favorable, so the exploration investment in Paleozoic basins, especially in the Murzuq Basin, increase a lot, and new discoveries are made increasingly. The Paleozoic basins are becoming hot spots in exploration, and they should be paid more attention by Chinese oil companies.