Sensitivity Analysis of the Influence of Fracturing Spacing in the Construction of Complex Fractures Network for Exploration and Production of Shale Gas/Shale Oil
The generation of oil occurs in sedimentary basins such as lakes, oceans, rivers and marshes, where sedimentary rocks with large amounts of fine grains, clay and silt are deposited over millions of years and carrying a certain volume of organic matter accumulated in the interior of their pores Such rocks are called source rocks . After the maturation of the organic matter present in the source rock, a natural fracture occurs in the same one, due to the conditions of high pressure and temperature, generating the primary migration of the hydrocarbon for its later imprisonment in a rock with high permo-porous properties, denominated rock reservoir. The next step of the conventional petroleum system generating mechanism is to surround the reservoir by means of traps and a sealant rock, i.e. with low permeability, e.g. evaporite (salt) or shale itself, thereby preventing the hydrocarbon be drained to other layers.
The shale gas /shale oil system is different from the conventional reservoirs (CR) mentioned above, since shales are part of a group known in the literature as unconventional reservoirs (NCR), because the primary migration has not yet occurred and also, because the shales have low permo-porous properties. Thus, the drilling operation is done straight on the source rock, so the shales are classified as source-reservoir rocks (SRR). The structure of the shales is basically formed by clastic or detrital rocks. Its formation is by means of transport by water or air. Such rocks are usually composed of silica, combined with other common minerals such as feldspar and clay minerals, e.g. quartz, limestone and feldspar, which have low granulometry, making it difficult to explore shale gas /shale oil without use stimulation techniques. Another characteristic of the shales is to possess high total organic content, TOC.
In the last decades, the advances in directional/horizontal drilling technologies, through rotary steerable systems (RSS), which allowed for better control of the well trajectory, and also in hydraulic fracture stimulation techniques allowed economical exploration and shale gas/shale oil reserves in the world.
The development of numerical methods that simulate the behavior of the network of complex fractures in shale gas/shale oil reservoirs has been a huge challenge among engineers of stimulation and researchers of the petroleum industry in the last decade.
Further article contains much information in the form of:
Parameters that influence the construction of the network of complex fractures in shale gas/shale oil reservoirs
Distribution and orientation of natural fractures
Equations for a hydraulic fracturing design in shales
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Fernando BF, Wellington C, Braga MB, Cl'audio A, Almir de Souza C (2019) Sensitivity Analysis of the Influence of Fracturings Spacing in the Construction of Complex Fractures Network For Exploration and Production of Shale Gas/Shale Oil. J Pet Environ Biotechnol. 10:397. doi: 10.4172/2157-7463.1000397