Impact of fractured irregular geometry on productivity of multiple fractured horizontal wells in a pressure-sensitive tight oil reservoir
SUN Lu1, LIU Yuetian1, WANG Yu1, ZHANG Yixin2, CHAI Rukuan1
1 Key Laboratory for Petroleum Engineering of the Ministry of Education, China University of Petroleum, Beijing 102249, China 2 Petroleum Engineering Institute, Missouri University of Science and Technology, Rolla, Missouri 63101, USA
At present, productivity models of fractured horizontal wells in tight reservoirs are based on the following 2 types. The first is a tri-linear flow model, in which the flow regions include three parts; outer reservoir, inner formation, and artificial fracture. The second is a triple porosity model, in which the flow path includes the matrix, natural fractures, and artificial fractures. However, these two models do not consider the irregular geometry of artificial fractures as well as the pressure sensitivity of natural fractures and artificial fractures. This paper mainly builds a transient model of a fractured horizontal well in a pressure-sensitive tight reservoir and conducts productivity analysis according to the irregular geometry of artificial fractures as well as the different features of pressure sensitivity in the stimulated reservoir volume (SRV) and artificial fractures. In the model, the irregular shape fractures are converted into rectangular microelements of variable width. Fracture permeability is introduced into the equation of pressure at the microelement section of artificial fractures. The permeability tensor is introduced into the equation of the average formation pressure in the SRV. The pressure sensitivity coefficient of artificial fractures and SRV is characterized. The permeability of double medium in SRV is described by the equivalent permeability. This model is used to describe the production of two wells B-1# and B-6# in Mid-Bakken, and the reliability of the model is illustrated. The results show that the model can simulate irregular morphological fractures flexibly and deal with the combination of different pressure sensitivity coefficients. Three kinds of shape fractures are wedged, necked and rectangular. When the pressure sensitivity coefficient of artificial fractures is greater than 0.15, there is an optimal bottom hole flow pressure for fractured horizontal wells. The greater the pressure sensitivity coefficient of natural fractures in SRV, the smaller the cumulative flow.
tight oil reservoir productivity of fractured horizontal well irregular geometry of fractures pressure-sensitive reasonable productivity working system
孙璐，刘月田，王宇，张艺馨，柴汝宽. 压敏油藏不规则裂缝形态对压裂水平井产能的影响[J]. 石油科学通报, 2018, 3(1): 45-56. SUN Lu, LIU Yuetian, WANG Yu, ZHANG Yixin, CHAI Rukuan. Impact of fractured irregular geometry on productivity of multiple fractured horizontal wells in a pressure-sensitive tight oil reservoir. Petroleum Science Bulletin, 2018, 3(1): 45-56.