Organization
Research Institute of Petroleum Engineering, SINOPEC, Beijing 100101, China
College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China
College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China
International Petroleum Exploration and Production Company, SINOPEC, Beijing 100083, China
Abstract
The geology condition of steeply-folded structure is complex, tectonic fractures develop and lost circulation happens usually during drilling, which brings great harm to safe drilling. Therefore, it is important to describe the tectonic fracture properties in order to predict effectively the thief formation and make measures of preventing lost circulation or bridging fractures. The paper presents a new approach which can carry out the pre-spud quantitative description of tectonic fracture in thief formation of steeply-folded structure. From the geological structure of the whole, combined with block macroeconomic mechanical characteristics and microscopic rock mechanism, and based on the geological structure model, the whole mechanical properties, loading history and condition, mechanical boundary condition and rock mechanics parameters are determined using this approach. The in-situ stress distribution of geological model for the units is calculated. Based on fracture mechanics and damage mechanics theory, the fracture development zone and fracture are judged and the structural fracture distribution is determined, obtaining the parameters such as structure fracture opening, porosity, permeability and fracture density, which can provide theory basis for the quantitative prediction of pre-spud loss and the selection of lost circulation material type and size.
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