Liu Z.,Northeast Petroleum University |
Liu Z.,State Key Laboratory Cultivation Base Jointly Constructed by Heilongjiang Province |
Suo S.,Northeast Petroleum University |
Pan L.,China National Offshore Oil Corporation |
And 2 more authors.
Oil and Gas Geology | Year: 2014
As a new field of unconventional oil and gas exploration and development in China, shallow gas is large in resource potential. Various data including core, well logging, 3D seismic and laboratory test data were integrated to study the shallow gas reservoir types, distribution characteristics, genetic mechanism and main controlling factors of shallow gas enrichment. The following results were obtained. The gas traps are controlled by anticline structure background and segmentation of multiple faults and there are mainly 4 types of gas reservoir traps, including anticline, faulted-anticline, fault-block and fault-nose. And the areal distribution of gas reservoirs is controlled by the positive structures and they mainly occur at the high positions of anticline and nose structures. Vertically, the single layer HI 5-HII 1, which is in the middle and lower parts of formation, is the main gas bearing interval affected by reservoir-cap assemblages. Gas in the Putaohua structure is mainly of biological genesis and is sourced from the first and second members of the Nenjiang Formation. In contrast, gas in the Puxi nosing structure is generated from the first and second members of the Nenjiang Formation, Qingshankou Formation and deeper formations, and is a mixture of biological gas, oil-type gas and abiogenetic gas. On this basis, the main controlling factors of shallow gas enrichment in Heidimiao reservoirs are summarized as follows: (1) multiple sets of good hydrocarbon source rocks offer a material basis for shallow gas; (2) reasonable timing of gas source faults and effective cap rock controls the horizons of shallow gas accumulation; (3) sandbodies of fluvial-dominated delta front act as high quality reservoirs; (4) lateral sealing capacity of fault ddetermines enrichment scale of shallow gas. Finally, the shallow gas accumulation pattern is established and showed as follows: tectonic reverse happened at the end of the Mingshui Formation stage, and the boundary faults in the areas with densely distributed faults were activated and opened, so that gas generated by the underlying source rocks migrated upward along the source rock-rooted faults into the high quality reservoirs connected well with the source rock-rooted faults, such as under water distributary channel, mouth bars and distal bars. After a short distance lateral migration in the high quality reservoirs, the shallow gas accumulated in anticlinal traps, fault-anticline, fault-block and fault-nose traps. The cumulative geological reserve of shallow gas was calculated to be 8.68 BCM by using volumetric methods on the basis of gas logging interpretation and 7 potential target areas were identified.
Wang Y.,Northeast Petroleum University |
Wang Y.,State Key Laboratory Cultivation Base Jointly Constructed by Heilongjiang Province |
Wang Y.,Universities in Heilongjiang Province |
Yan M.,Northeast Petroleum University |
And 8 more authors.
Petroleum Exploration and Development | Year: 2015
From the deformation characteristics of two walls of a fault caused by fault activities, the activation of faults in the critical moment of oil and gas accumulation (structural inversion period) was analyzed to determine the source faults in the Upper Cretaceous Putaohua oil layer of the Sanzhao sag in Songliao Basin. Based on the previous classification and research results of activity patterns of the faults in the Sanzhao sag, the analysis of the structural deformation characteristics during the deposition of the 2nd and 3rd members of the Upper Cretaceous Nenjiang Formation and the inversion reveals that the feature of cutting to T06 reflection layer (bottom interface of the third member of the Nenjiang Formation) can not be taken as the basis to judge whether the faults were activated during the inversion or not. But during the structural inversion period, the structural deformation caused by faults would lead to fault-propagation inverted folds and fault-bend inverted folds, which would further lead to obvious deformation differences between hanging walls and foot walls of faults, this can be taken as the basis to determine if the faults were activated or not in the inversion period, and then the source faults of the Putaohua oil layer can be determined. Furthermore the source faults can be divided into two kinds, concealed faults and penetrating faults, according to if the source faults cut through layers of inversion period or not. These two kinds of source faults show more obvious control over the planar oil distribution in the Putaohua layer than the previous study results. © 2015 Research Institute of Petroleum Exploration & Development, PetroChina.
Song Y.,Northeast Petroleum University |
Song Y.,State Key Laboratory Cultivation Base Jointly Constructed by Heilongjiang Province |
Li X.,Northeast Petroleum University |
Tang X.,Northeast Petroleum University |
And 2 more authors.
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2014
Most of the commonly used resistivity models are unable to give a precise description of conductive laws of sands whose rock matrix contains a certain amount of pyrite, therefore it is necessary to study the conductive laws and to propose a matrix-conducting resistivity model. The effects of water resistivity and conductive matrix grain content in matrix-conducting clean sands are first analyzed by using laboratory resistivity measurements of artificial and field samples, in which the rock matrix is composed partially or entirely of conductive grains. The results shown in a log-log graph suggest nonlinear relationships between formation resistivity factor and porosity, and between formation resistivity index and water saturation, respectively. Values of the formation resistivity factor and the index decrease with decreasing water conductivity, or increasing conductive matrix grain content. Second, based on the compositions of matrix-conducting clean sands and the characteristics of connectivity conductance theory, matrix-conducting clean sands are divided into non-conducting matrix phase, conductive matrix phase and free fluid phase. Since the connectivity conductance equation applies to only one conducting composition and one non-conducting composition, while the HB equation can describe systems of two conducting compositions, a new matrix-conducting resistivity model for clean sands is proposed combining the connectivity conductance theory and the HB equation. The results show that the theoretical relationships between formation resistivity factor and porosity, and between formation resistivity index and water saturation predicted by the proposed model are consistent with the experimental values, and the proposed model is in compliance with meaningful physical bounds. The matrix-conducting resistivity model for clean sands can describe the conductive law of matrix-conducting clean sands, in which rock matrix is composed entirely or partially of conductive grains. The proposed model can be applied to quantitatively calculate saturation in matrix-conducting low resistivity reservoirs.