Interference well testing-variable fluid flow rate

2015

Production data analysis is an important tool for estimating important reservoir parameters. In particular, determining the average reservoir pressure (pav) and tracking its change with time is critical to analyzing and optimizing reservoir performance. The traditional method for determining pav involves pressure buildup tests. A direct method for estimating (pav) from flowing pressures and rate data is available. However, the method is for an idealized case that assumes constant production rate during pseudo steady-state (PSS) flow, which is not generally true for real wells. This research extends that approach so that it can be used to analyze field data with variable rates/variable pressures during boundary-dominated flow (BDF). For gas reservoirs, pseudopressure and pseudotime functions are used to linearize the gas flow equation and enable the liquid diffusivity solution to satisfy gas behavior when analyzing gas test data. This project investigated when the use of pseudo time becomes necessity, and developed a technique to complete the linearization of diffusivity equation without using conventional pseudo time. A further objective of this research included extending our modified approach into a multi-well system. This modified approach is based on a combination of rate-normalized pressure and superposition-time function. The mathematical basis is presented in support of this approach, and the method is validated with synthetic examples and verified with field data. This modified approach is used to estimate average-reservoir pressure, calculate both connected oil volume and reservoir drainage area as a function of time, and provide a reasonable estimation of the reservoir's shape factor. These calculations, allowing the reservoir performance and management to be properly evaluated. v ACKNOWLEDGMENTS First and foremost, all the praise and gratitude be to Allah, the sole Creator and Sustainer of the Universe, he is the one that deserves all the praise. Peace be upon his prophet Muhammad. I would like to express my most sincere appreciation to my advisor, Dr. Flori for his invaluable guidance, encouragement, and his patience in helping bring this work to completion. Appreciation is also extended to Mr. Shah Kabir, global reservoir engineer at Hess Corporation, for his invaluable help and suggestions that played a vital role to get part from this work accepted for publishing.

Journal of The Japan Petroleum Institute, 1998

Analysis of variable flow rate tests has been of special interest recently because, in many cases, it is impractical to keep a flow rate constant long enough to perform a drawdown test. Further, in many other drawdown and buildup tests, the early data were influenced by wellbore storage effects, and the duration of these effects could be quite long for low-permeability reservoirs. For hydraulically fractured wells, the early-time period represents linear flow. Current methods of analysis of multirate tests, in fractured wells, use both the superposition of constant-rate solution method and the rate-normalized type-curve matching for the pseudoradial flow period; and only the rate-normalized type-curve analysis for the linear flow period. This paper presents a mathematical model which describes drawdown and buildup tests in hydraulically fractured wells. A new and simple method of analysis based on this model is presented for drawdown and buildup tests in oil and gas wells. This new method uses a specialized plot approach to analyze the linear flow data and combines it with the superposition of constant-rate solution method for the analysis of pseudoradial flow data. It does not require prior knowledge of the fracture type (uniform-flux or infinite-conductivity); in fact it predicts the fracture type. This method is useful for the analysis of simultaneously measured downhole pressure and sandface rate data. Data of three well tests reported in the literature were analyzed by the new method and the results including the comparison with those obtained by other methods are presented and discussed.

All Days, 1995

This paper was selected for presentation by an SPE Program Committee following review o f information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by th e author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Papers presented at SPE meetings are subject to publication review by Edi torial Committees of the Society of Petroleum Engineers. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Write Librarian, SPE,

2017

Well test analysis of multi-layer reservoir comprises several parts. The first part concerns the estimation of parameters values and next considers finding an appropriate method to determine the unknown reservoir parameters. If the initial estimations are less accurate and weak, the final assessment may lead to incorrect results, which are totally different from the reality. Utilizing Automated Type-Curve Matching method by means of computers is effective and successful. In addition, it has priority over the ordinary analysis methods, and numerical calculations are performed with higher speed thereby causing fewer errors. In this study, first, a numerical simulation of reservoir was conducted by means of Eclipse 100 software and then its production and pressure results were introduced to Ecrin software of well test analysis. Different states were investigated in the analyzer to obtain the minimum error, and suggestions, including effect of regression point selection, initial guess, ...

Dyna-colombia, 2020

The naturally fractured reservoir characterization is crucial because it can help to predict the flow pattern of fluids, and the storativity ratio of the fractures and to understand whether two or more wells have communication, among others. This paper presents a practical methodology for interpreting interference tests in naturally fractured reservoirs using characteristic points found on the pressure derivative curve. These kinds of tests describe a system that consists of a producing well and an observation well separated by a distance (r). Using characteristic points and features found on the pressure and pressure derivative log-log plot, Analytical expressions were developed from the characteristic points of the pressure and pressure derivative log-log plot to determine the interporosity flow parameter (λ) and the storativity ratio of the fractures (ω). Finally, examples are used to successfully verify the expressions developed so that the naturallyfractured parameters were reproduced with good accuracy.

SPE Annual Technical Conference and Exhibition, 2011

Complex heterogeneous reservoirs penetrated by deviated wells pose significant challenges when modeling and interpreting packer-and probe-type formation-tester measurements. This paper introduces a streamline-based method specifically designed for near-wellbore fluid-flow modeling in vertical and deviated wells. The primary application of the method is for efficient simulation and automatic history matching of formation-tester measurements in the presence of invasion and variable petrophysical and geometrical properties. Based on the spatial distribution of pressure calculated with a previously validated near-wellbore finite-difference model (FDM), the method traces streamlines from the reservoir into fluid sampling probes. The calculated spatial distribution of pressure is input to the streamline-based method to propagate the spatial distribution of water saturation. Subsequently, the calculated spatial distribution of water saturation is input to the FDM to update the spatial distribution of pressure. Streamlines are then recalculated and this repeated pressure-saturation procedure continues until reaching the desired final simulation time.

The Way Ahead, 2014

2018

Proceedings of Middle East Oil Show, 1993

Interference analysis in naturally fractured reservoirs can serve as an extremely effective reservoir characterization tool. Because of the conductive nature of fractures, rapid segregation of gas-oil in naturally fractured reservoirs is corrunon place. Additionally, the upward movement of bottom water can rapidly displace the water oil contact influencing the behavior of individual wells. The purpose of the study is to address an important class of interference test where the contribution of gas-cap support or water oil contact movement can significantly affect the estimated parameters such as storativity and transmissivity. The theoretical framework needed to model interference response in a naturally fractured reservoir producing an oil zone overlain by a gas cap or affected by a desired outer boundary condition, including water-influx effects, is derived and discussed. General pressure response solutions ( for the active and the observation well) are derived for a dual flow double porosity naturally fractured reservoir. Furthermore, the effects attributed to properties of individual wells such as wellbore storage and skin damage are incorporated in the general solutions and studied.