| Connected volume of reservoir sand bodies is an important factor for the size and abundance of the litho logic traps, which forms a great influence for the development of oil and gas fields. Oil and gas can develop only from the reservoir rock connected with borehole, so it is indeed very important to clarify the river sand body static connectivity of oil and gas reservoirs. In oilfield development, it only describes the connectivity of the reservoir sand bodies; quantitatively evaluates the influencing factors of the sand body connected volumes, and development wells can drill favorable reservoir, producer-injector patterns more reasonable and enhance the oil recovery. However, how to properly calculate the reservoir sand body connectivity volumes and quantitatively evaluate the influencing factors of the sand body connected volumes are the problems faced by geologists.Three dimensional reservoir modeling from the perspective of three dimensional space to study the reservoir quantitatively, the core is the study of reservoir through the integration of multi-disciplinary and the realization of three-dimensional visualization.3D reservoir model overcomes the limitations of two-dimensional map to describe the three-dimensional reservoir, and quantitatively characterize reservoir characteristics from the three-dimensional space. Object-based stochastic simulation method chooses the object as the basic simulation unit, and is able to better reproduce the geometry of the simulated object. Fluvsim method is better simulation the geometry of the object than the conventional object-based stochastic simulation method. Because of this advantage, we have chosen the Fluvsim algorithm to achieve a simulation of river sand body. Deutsch’s (1996) Fluvsim method has some advantages over conventional object-based fluvial reservoir modeling:(1)an explicit reversible hierarchy of coordinate transformations,(2) geologically intuitive and accessible input data controlling channel sizes and shapes,(3) explicit control over vertically varying and areally varying facies proportions,(4) realistic asymmetric channel geometries,(5) realistic non-undulating channel top surfaces. However, Fluvsim still has a common problem that it is difficult for conditioning, especially when there has variety of conditional data.The orthogonal experimental design method is an important branch of statistical mathematics. It is a scientific calculation which is based on probability theory of mathematical statistics, technical expertise and practical experience. The method full use of the standardized orthogonal table to arrange the test program, calculate and analyze the results.It can ultimately reduce the number of trials to shorten the test cycle, and rapidly find the optimum program. Orthogonal experimental design is divided into seven-step:determine the fluctuation range of factors, determine investigate index, determine the levels of factors’s table, choose the appropriate orthogonal table to designe table head, determine the test program and record test results, calculate and analyse test results,and the last confirmatory test.The test based on reservoir geological repository (for example, the type of sand body, size) builds3-D models and analyses connectivity. I choose connected Volumes module in the the petrel modeling software and orthogonal design assistant Ⅱ V3.1, using the orthogonal experimental method to complete. Determine the fluctuation range of factors that affect the volume of reservoir sand body connectivity, select the appropriate level of each factor. And then use the orthogonal design assistant Ⅱ V3.1to develop orthogonal table, set specific parameters in petrel software facies simulation according to the orthogonal table. Orthogonal table has how many test, and do how many corresponding facies simulations in petrel. Then, using the connected volumes module in petrel calculates the connected volume of each facies model. Finally, using variance analysis method in the orthogonal design assistant Ⅱ V3.1to analyse test results and quantitatively evaluate the influencing factors of the sand body connected volumes.Results are as follows:(1) On the basis of extensive literature research and data analysis, choose NTG, river width, W:T, curvature, rivers deviate from the source and well spacing as the six parameters which affect the fluvial sand body connectivity volumes. Determine the different levels based on literature research and geological knowledge base;(2) According to the number of variables and levels, use experimental design software to design the simulation program. Full-scale experimental design requires729simulations. However, this program requires only18experiments, greatly improving the efficiency;(3) The study have shown that the overall orderof thefactors controlling the sand body connected volumes is:NTG, river width, well spacing, curvature;(4) As NTG increased, river width’s influence of sand body connectivity volumes decreases gradually from the highly significance to no effect; W:T’s influence of sand body connectivity volumes first decreases and then increases, from not significance but have effect to no effect and then to not significance but have effect; curvature’s influence of sand body connectivity volumes first decreases and then increases, from more significant to no effect and then to not significance but have effect; deviation angle’s influence of sand body connectivity volumes first increases and then decreases, from no effect to not significance but have effect and then to no effect; Well spacing’s influence of sand body connectivity volumes decreases gradually from significance to not significance but have effect and then to no effect;(5) Clear from the key geological factors affect the connectivity of the sand body on the conditions of the different well spacing. Guide the geological research and optimize well location design. With the deepening of the degree of oil field development, well spacing has infilled. NTG’s influence of sand body connectivity volumes first decrease and then increase, it is always highly significant; river width’s influence of sand body connectivity volumes first increase and then decrease, from more significant to significance; curvature’s influence of sand body connectivity volumes first increase and then decrease, from not significance but have effect and then to no effect; river deviation angle’s influence of sand body connectivity volumes first increases and then decreases, from no effect to not significance but have effect and then to no effect. |
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