Study On Reservoir Formation Mechanism Of The Volume Fracturing On Yanchang Shale Gas Reservoirs In Continental Faces

Shale gas refers stored in organic-rich shales and laminated in order to adsorption or freestate as the main mode of existence of unconventional gas. With the success of the U.S. shalegas revolution, people gradually realize that can be a lot of dark shale hydrocarbon,hydrocarbon reservoir formation reservoir-type self-generated from oil and gas accumulation.Increase the development of some new technology, especially multi-segmented volumecluster fracturing and horizontal well fracturing applications, the successful implementationof the shale oil and gas exploration. Volume fracturing is generally defined as: the waythrough fractured reservoir seepage will have the ability to effectively "break", the artificialcrack communicate with natural fractures, forming a network of cracks, cracks in the wall sothat the contact area with the largest reservoir matrix, making the flow of oil and gas from anydirection from the matrix to crack the "shortest" greatly enhance the overall permeability ofthe reservoir, to achieve the reservoir in length, width,"three-dimensional reconstruction of"high dimensional direction.Theory and research papers in the full status of horizontal well technology research athome and abroad on the basis of multi-cluster fracturing, according to extend continentalshale gas reservoir rock mechanical properties and to stress characteristics, using the finiteelement method were analyzed and rock mechanical properties cluster spacing and otherfactors affecting the formation of cracks and get sewing network formation mechanism;optimized fracturing number of clusters, cluster spacing, blocks the formation of a certainguiding optimization program; field data on the use of multi-cluster fracturing of horizontalwells slit width was simulated.The main conclusions of this paper, based on the results of these studies have, in thecrack extends, on both sides, upper and lower ends of the crack tip height direction lengthwisedirection, due to the role of shear stress, are likely to produce the crack plane perpendicular tothe main shear failure, the initial formation of the seam and then the network; compared to asingle cluster of two clusters fracturing fracturing synchronization less likely to fracture if twoclusters, then the induced shear failure, the network will make it difficult to form the seam,this may With the decrease of the distance between the clusters and become smaller; If the crack is not synchronized multi-cluster expansion, then after the first extension of the crackwill generate pressure to open the crack extension inhibition, and the more recent clusterspacing, the more obvious inhibition; the mechanical properties of rock and earth stressparameters, the minimum horizontal stress fracturing effect on the most significant, which isthe minimum horizontal stress smaller, more easily form a seam network; crack crack will bepressed to open the adjacent position to produce an additional stress, inhibiting its openingand extension. This article uses the finite element method to calculate the impact of the scopeof this additional stress. This additional stress has a trend that the maximum value of the firstcracks, the cracks close distance between the first reduced at a faster, as the distance increases,the additional stress decreases slowly. Therefore, if each cluster multibank fracturing crackcrack extends not simultaneously, the need to increase the cracking fracture when thefracturing pressure to crack extension. These conclusions are better able to get the guidance ofhorizontal wells oilfield cluster optimized multi-segmented design and site constructionvolume fracturing.