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Zhang X.,Southwest Petroleum University | Gou R.,Southwest Petroleum University | Liang H.,Tarim Oil and Gas Branch Company | Gong Y.,Southwest Petroleum University | Xiao P.,Southwest Petroleum University
Advanced Materials Research | Year: 2011

Drilling technology of ultra-deep well is still the focal point of drilling research, there are many difficulties in ultra-deep well drilling, such as bottom hole with high temperature and high pressure, complex geology, borehole with sharp dogleg, etc. These technical difficulties put forward higher request in casing running, well quality must be controlled strictly in order to run larger diameter combination casing string successfully. Well quality is closely linked with the drifting drilling assembly design. The accurate stiffness ratio calculation is the key prerequisite of drifting drilling assembly design. In this paper, a new mechanical model is applied to simulate deflection of the drifting drilling assembly. The solution of variable cross-section beam's equivalent stiffness is applied to solve the stiffness of the drifting drilling assembly. Modified stiffness ratio calculation method for drifting drilling assembly and casing string is proposed. In the process of calculation formula derivation, the conservation of energy law has been used multiple times. At last, the VB computer program is compiled, which contains the modified calculation method. The computer program calculation value is larger than the conventional method's calculation value. Modified calculation method is more reasonable, which has important significance for drifting drilling assembly optimal design. © (2011) Trans Tech Publications. Source


Zhang Y.-F.,Southwest Petroleum University | Wang Z.-Y.,Southwest Petroleum University | Qu H.-Z.,Southwest Petroleum University | Luo C.-S.,Tarim Oil and Gas Branch Company | Li Y.,CAS Nanjing Institute of Geology and Palaeontology
Journal of Central South University | Year: 2014

In order to reveal the relationship between the penecontemporaneous karstification and sedimentary microtopography in sequence stratigraphy, the sequence stratigraphic framework of Lianglitage formation in Upper Ordovician is studied according to the well drilling, logging, geophysical data, detailed observations of core and the paleontology. The Lianglitage formation belongs to the sequence IV of Ordovician. The second member of Lianglitage formation is prograde sedimentation in highstand systems tract, and is favorable for developing reef flat. The development scale and thickness of reef flat are controlled by the variation of secondary sea level. The types and characteristics of karst in the highstand systems tract show that the late highstand systems tract is dissolved and cemented by the meteoric fresh water and mixed water. Penecontemporaneous karstification is developed at the top of parasequence and high place of geomorphology. Atmospheric diagenetic lens is formed. The developing regulations and controlling factors of penecontemporaneous karstification can provide new clues to the prediction and exploration of favorable reservoir in this area. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg. Source


Zhang P.,Peking University | Hou G.,Peking University | Pan W.,Tarim Oil and Gas Branch Company | Qi Y.,Tarim Oil and Gas Branch Company | Meng Q.,Peking University
Scientia Geologica Sinica | Year: 2014

Four periods of structural stress fields can be recognized since Sinian System in Kuruktag and adjacent areas based on structural evolution analysis, that is Early Paleozoic, Later Paleozoic, Mesozoic and Cenzoic. Their maximum principal stress orientation are respectively NNE, NWW-NW, NE and NNE-SN, which are derived from the occurrence data of the stress response structures, i. e., joints, folds and dykes. Furthermore, the author simulated the stress field since Neogene based on 2D finite element method, to deeply analyze the following questions: Distribution and direction of stresses in the study area, influence of the geometry model for the stress field, as well as the dynamics of structures related to stress field. Source


Liu C.-L.,Chinese Academy of Geological Sciences | Cao Y.-T.,Chinese Academy of Geological Sciences | Yang H.-J.,Tarim Oil and Gas Branch Company | Jiao P.-C.,Chinese Academy of Geological Sciences | Gu Q.-Y.,Tarim Oil and Gas Branch Company
Acta Geoscientica Sinica | Year: 2013

Evaporites with large thickness were formed in Kuqa foreland basin during Paleogene-Neogene period. The paleo-salt lake deposits during Paleocene were mainly distributed in central and estern Baicheng depression in the west of Kuqa Basin; then the paleo-salt lake deposits expanded into almost entire Baicheng depression and both depocenter and brine enrichment center of salt lake located in the north part during Eocene; after that the salt lake deposits were still distributed in the most of the depression during Oligocene, but evaporites and brine enrichment center had already moved to its south, and hence the previous tectonic pattern of the half-graben basin characterized by "deep in the north and shallow in the south" was remarkably altered; finally, with the migration of the depocenter from Baicheng depression to Yangxia depression in the east of the basin during Miocene, the salt lake sediments also moved eastward. The brine enrichment centers occured as bead distribution during Paleocene to Miocene. The evolution of paleogeography of Kuqa basin indicated that the development and migration of sub-depression was strongly influenced by tectonic activities in the baisn, which controled the paleogeography of salt lake (e.g. depocenter, material source and brine enrichment center) and might have played an important role in the later potential formation of potash deposits. Further analysis reveals that enrichment tendency for potassium in evaporite sequence also controlled obviously by the paleogeographic changes of the Basin, namely, potassium enrichments should have occurred in the regions with large area and great thickness of the salt deposits. The fact that, potassium content of salt rock cuttings in some oil drill holes gradually increased from the bottom to the top, for example, in the western Baicheng depression, the maximum values of potassium content are 1.07%, 1.43%, 3.05% upward in one drill hole, and in the eastern Yangxia depression, the potassium content varies from 0.008% to 0.152%, was just the geochemical response to the enrichment trend of potassium content controlled by change of lithofacies and paleogeography in the paleo-salt lake. From the above, it can predict that the Kuqa foreland basin has good potash metallogenic prospects, which might exist in brine enrichment center of Baicheng depression in Eocene time and probably migrate to the center of Yangxia depression in Miocene time. Source


Ju W.,Peking University | Ju W.,Petrochina | Hou G.,Peking University | Huang S.,Tarim Oil and Gas Branch Company | And 2 more authors.
Geotectonica et Metallogenia | Year: 2013

The Lower Jurassic Ahe Formation sandstone characterized by low porosity and low permeability is the main reservoir in the Yinan-Tuzi area of the Kuqa Depression, within which the well-developed structural fractures serve as important migration pathways and accumulation spaces. On the basis of acoustic emission and rock mechanics parameter testing, considering the influence of faults on the fracture forming, we simulate the main fracture forming period paleostress field and predict the distribution of structural fractures with the constraints of cores using 3D finite element method. The simulation results show that the Yiqikelike anticlinal zone and the Well Yinan 2 area are the most favorable areas for structural fractures, with density >1.4 m-1. The structural fracture density decreases gradually towards the Tuzi area and south of Well Yinan 2 area, varying in the range of 0 to 0.4 m-1. The present study results can provide us new geological evidence for the fracture development evaluation, and reservoir prospecting and exploitation in the area. Source

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