Stimulated reservoir volume is an effective stimulation measure and creates a complex fracture network, but the description and characterization of fracture network are very difficult. Well test analysis is a common method to describe the fracture network, and it is the key to build a proper interpretation model. However, most published works only consider the shape of the fractured area or the stress sensitivity effect, and few works take both factors into account. In this paper, based on reservoir properties and flow law after a stimulated reservoir volume, an interpretation model is established with an arbitrary shape of the fractured area and stress sensitivity effect of different flow areas. The model is solved to conduct the pressure response using Laplace transform, point source function, and boundary element theory. The influence of fractures’ parameters and stress sensitivity effect is analyzed on the pressure behavior. Results from this study show that the special flow regimes for a horizontal well with a stimulated reservoir volume are (1) bilinear flow dominated by hydraulic fractures, (2) linear flow dominated by formation around the hydraulic fractures, (3) crossflow from a matrix system to the fractured area, and (4) radial flow control by properties of the fractured area. Parameters of hydraulic fractures mainly affect the early stage of pressure behavior. On the contrary, the stress-sensitive effect mainly affects the middle and late stages; the stronger the stress sensitivity effect is, the more obvious the effect is. The findings of this study can help for better understanding of the fracture network in a tight oil reservoir with a stimulated reservoir volume.

Autonomous inflow control device (AICD) completion has been applied in many conventional oil and gas reservoirs and has effectively controlled the water invasion. However, the method for designing and optimizing of AICD in sour gas reservoirs is still lacking. The objective of the proposed paper is to establish a numerical simulation and optimization method to evaluate and optimize the performance of AICD completion in water-bearing sour gas reservoirs. Firstly, a sulfur deposition saturation model is established considering non-darcy flow and stress sensitivity in sour gas reservoirs, meanwhile, time-varying skin factor is introduced to represent the influence of sulfur deposition on permeability. Secondly, a new type of AICD is designed, which has large flow channels and vortex chamber to satisfy the need of restraining water invasion and sulfur plugging in sour gas reservoirs. Finally, a reservoir-wellbore simulation method is established, which considers the sulfur deposition in the reservoir and the new AICDs in the wellbore, then the key parameters of AICD is optimized by orthogonal test and range analysis. The results of the numerical simulation show that the simulation and optimization method can effectively optimized the key parameters of AICD and the optimized AICD completion has good water invasion restriction capacity in water-bearing sour gas reservoirs. The optimized AICD completion causes little additional pressure drop compared to perforation completion in sour gas reservoirs, and the maximum additional pressure drop is less than 0.67 MPa, which means the optimized AICD completion is able to control water invasion as well as maintain normal gas production of sour gas wells. Besides, the optimized AICD completion decreases both the daily water production and the cumulative water production compared to perforation completion in sour gas reservoirs. In the last stage of the tenth year prediction period, the cumulative water production with AICD completion decreases by about 22.7% compared to that with perforation completion. In conclusion, the simulation and optimization method can be used for guiding the rational application of AICD completion in water-bearing sour gas reservoirs.

Oil flow in inter-salt shale oil reservoirs is different from that of other oil fields due to its high salt content. Dissolution and diffusion occur when the salt minerals meet the water-based working fluid, resulting in drastic changes in the shale’s permeability. In addition, ignoring the stress-sensitive effect will cause significant errors in naturally fractured reservoirs for a large number of the natural fractures developed in shales. This study presents a transient pressure behavior model for a multi-stage fractured horizontal well (MFHW) in inter-salt shale oil reservoirs, considering the dissolution of salt and the stress sensitivity mentioned above. The analytical solution of our model was obtained by applying the methods of Pedrosa’s linearization, the perturbation technique and Laplace transformation. The transient pressure of a multi-stage fractured horizontal well in an inter-salt shale oil reservoir was obtained in real space by using the method of Stehfest’s numerical inversion. The bi-logarithmic-type curves thus obtained reflected the characteristics of the transient pressure behavior of a MFHW for the inter-salt shale oil reservoirs, and eight flow periods were recognized in the type curves. The effects of salt dissolution, stress sensitivity, the storativity ratio and other parameters on the type curves were analyzed thoroughly, which is of great significance for understanding the transient flow behavior of inter-salt shale oil reservoirs.

Throttle valve is an important device in well control manifold. During field use, the seat and plug of the valve often fail of erosion, posing a serious security risk to well control. Erosion resistance device is a tool to counter the problem. Using the three-dimensional (3D) flow field analysis software of computational fluid dynamics (CFD), this paper numerically simulates the flow field of erosion resistance device. The results show that, under the given boundary conditions, the mean velocity of the water flow does not change much as it passes through the inlet and outlet of erosion resistance device. The flow velocity changes very slightly, as the fluid pressure difference varies from 0.29MPa to 0.3MPa. The maximum flow velocity (16.36m/s) appears on the outlet wall of the device, beneath the alloy head. The alloy head, which is made of hard alloy material, is not greatly affected by the maximum velocity. Thus, the erosion resistance device will not be severely eroded. This means the erosion resistance device can work normally under actual conditions.

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