Horizontal wells are thought to be necessary in formations with low-permeability to increase the recovery and reduce the risk of drilling a dry hole. The horizontal well may cross natural fissures. Although hydraulically fracturing horizontal wells in such formations is a risky job, it may be necessary in order to achieve commercial production. This is especially true for naturally fractured gas reservoirs with matrix permeability in microdarcies and where natural-fracture network does not contribute considerably to the flow from the reservoir into the wellbore.

This study investigates the transient pressure behavior of a multiply fractured horizontal well (MFHW), as well as the long time performance of such a completion in an anisotropic naturally fractured reservoir of infinite extent.

Combining boundary element method and Laplace transform, single-fracture solution is considered first as it constitutes the core part of the multiple-fracture model. Then, a solution to multiply fractured horizontal wells is presented, which assumes fractures of distinct properties, it allows for unequal spacing between fractures, and permits the perforation of portions of the interval between fractures. Furthermore, it allows the juxtaposition of any number of perforated intervals and any number of fractures.

The pseudo-steady state is considered to account for the fluid transfer between the matrix blocks and the fracture network.

Due to its simplicity, accuracy, and reliability, procedures for using the new technique referred to as "Tiab’s Direct Synthesis" have been developed to analyze the transient pressure and pressure derivative behavior of a MFHW in a naturally fractured reservoir. Individual fracture properties can be determined if individual flow rate contributions are measured, otherwise an average conductivity and half-length is determined.

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