Drop of Pressure Behavior of Open-Cell Aluminum Foams at High Pressure Flow

Open-cell aluminum foams were produced by the replication technique in three different pore sizes, ranging from 0.71 to 4.75 mm. The manufactured specimens were physically characterized, determining their porosity, relative density, pores per inch and interconnection windows density. A new experimental design is proposed in order to assess the drop of pressure behavior resulting from the injection of gasoline additive at increasing high pressure intervals, ranging from 200 to 25,000 psi, reproducing the tests at room temperature and 200 °C. The regime governing the flow through the investigated samples was determined as a function of flowrate and the foams physical properties. The structural capacity of open-cell Al foams to conduct highly pressurized flow was evaluated by means of compression tests. It was found that at room temperature, the drop of pressure behavior is strongly associated to physical parameters, whilst at 200 °C, dimensional and geometrical properties are negligible. In addition, in this investigation, it is presumed that the studied foams have the structural capacity to conduct fluids at critical conditions of pressure and temperature.

Semi-analytical model of multiple fractured horizontal well across a discontinuity in a linear composite reservoir

Many geologic settings can be treated as linear composite (LC) reservoirs, where linear discontinuities divide the formation into multiple zones with different properties. Although there have been many studies on pressure behavior of production wells in an LC reservoir, most of the studies focus on vertical wells. The modeling of multiple fractured horizontal (MFH) wells in an LC reservoir remains limited. The goal of the present work is to propose a general semi-analytical model of an MFH well situated anywhere in a two-zone LC reservoir. This model can take into account the situation where the horizontal well intersects with the discontinuity and hydraulic fractures are distributed in both the two zones. According to the point-source function method, the semi-analytical solution for an MFH well in LC reservoirs is derived by using superposition principle, fracture discrete scheme and numerical inversion algorithm of Laplace transformation. Type curves of MFH wells far away from a discontinuity and across a discontinuity in an LC reservoir are drawn and analysed, respectively. Furthermore, the effects of some parameters on pressure behavior and rate response of an MFH well across a discontinuity are studied. This research finds that the pressure behavior and rate response of an MFH well across a discontinuity are significantly affected by the well location, properties of hydraulic fractures and formation properties.

Transient Pressure Behavior of Complex Fracture Networks in Unconventional Reservoirs

Unconventional resources have been successfully exploited with technological advancements in horizontal-drilling and multistage hydraulic-fracturing, especially in North America. Due to preexisting natural fractures and the presence of stress isotropy, several complex fracture networks can be generated during fracturing operations in unconventional reservoirs. Using the DVS method, a semianalytical model was created to analyze the transient pressure behavior of a complex fracture network in which hydraulic and natural fractures interconnect with inclined angles. In this model, the complex fracture network can be divided into a proper number of segments. With this approach, we are able to focus on a detailed description of the network properties, such as the complex geometry and varying conductivity of the fracture. The accuracy of the new model was demonstrated by ECLIPSE. Using this method, we defined six flow patterns: linear flow, fracture interference flow, transitional flow, biradial flow, pseudoradial flow, and boundary response flow. A sensitivity analysis was conducted to analyze each of these flow regimes. This work provides a useful tool for reservoir engineers for fracture designing as well as estimating the performance of a complex fracture network.

Dynamic Reservoir Analysis of Corrib Field Surveillance Data Through the Use of Advanced Deconvolution Techniques

This paper presents an analysis of the Corrib field surveillance dynamic pressure and rate data. The Corrib field, on production since December 2015, is a gas reservoir developed with six wells. The field static gas initially in place (GIIP) is around 1.2 Tcf of dry gas and the reservoir is comprised of a complex heterogeneous sandstone consisting of a high net to gross sequence of low sinuosity braided fluvial channel, sheet sand, playa and sandflat facies of varying reservoir quality (from single to hundreds of millidarcys) with an abundance of mapped faults. The dynamic reservoir analysis approach used in this study is based on a form of pressure-rate deconvolution that has been presented in an earlier paper SPE-195441 for the Tamar field, Israel. The pressure transient analysis (PTA) software that implements this analysis capability handles both singlewell and multi-well analysis problems. From a preliminary review of Corrib field dynamic behavior, it was concluded that this field data can be analyzed using single-well pressure-rate deconvolution applied to the data of each reservoir well separately. This contrasts with the Tamar field that required a true multiwell deconvolution analysis approach. Different approaches in these cases are dictated by the differences in reservoir architecture, geology, offtake strategy and the character of connectivity across these two fields. There are several pressure-rate deconvolution algorithms implemented in different PTA software tools used in the industry. All these algorithms implement a form of automatic regression and are sensitive to the quality of pressure and rate data that serve as input into the deconvolution algorithm. These automatic algorithms are often not robust enough to be used with surveillance type data acquired during long term production operations. The deconvolution approach used in this work is not automatic and, as a result, the deconvolution results are not as sensitive to the data quality. Rather, it relies on specialized software that facilitates manual reconstruction of constant rate drawdown responses. This human approach in combination with specialized software allows an engineer not to just reconstruct a drawdown response but to "explore" the pressure and rate data to develop significant insights of the dynamic reservoir behavior. This deeper understanding is an additional advantage over automated techniques and is the purpose of reservoir analysis. The Corrib field analysis discussed in this paper is a demonstration of what can be achieved using this combination of human intelligence and specialized software tools. Demonstration of the workflow used for manual reconstruction of deconvolved response functions and the role of the specialized software used that implements this workflow is explained. In the course of this reconstruction, an "exploration" process of trying to reconstruct the transient pressure behavior reflected in the data is engaged/utilized. Once reconstructed, this response is interpreted in terms of reservoir and well properties. The end result of this investigation is a deep understanding of the Corrib gas field dynamic behavior not easily obtained from conventional PTA methods. For example, it shows that early production data clearly exhibit signs of interference between wells. However, once the field production drops off the plateau period and the well production starts to decline, the six producing wells dynamically divide the reservoir into separate drainage areas and the well interference in a way "disappears" - the wells behave as if each of them produces from its own drainage compartment. This allows pressure rate deconvolution on a single-well basis, based on each compartment instead of using multi-well deconvolution on the field as a whole. The pore volume of each such compartment is reflected in the late time pressure behavior of the respective drawdown response associated with the well data. The sum of these individual pore volumes per well in the field yields the total pore volume connected to the wells that is supported by the reservoir dynamic behavior. These insights are reinforced by the use of synthetic models to provide clarity and understanding of the drainage compartment theory used during Corrib analysis.