Downhole Mass Flow Rate Measurements Enhance the Analysis of Well Test Data: A Field Example (original) (raw)
Related papers
A New Method of Analyzing Well Tests in Fractured Wells Using Sandface Pressure and Rate Data
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.
Interference well testing-variable fluid flow rate
OURNAL OF GEOPHYSICS AND ENGINEERING, 2008
At present, when conducting an interference well test, a constant flow rate (at the 'active' well) is utilized, and the type-curve matching technique (where only 2-3 values of pressure drops are matched) is used to estimate the porosity-total compressibility product and formation permeability. For oil and geothermal reservoirs with low formation permeability, the duration of the test may require an extended period, and it can be challenging to maintain a constant flow rate. The qualitative term 'long' period means that (at a given distance between the 'active' and 'observational' well) more test time (for low permeability formations) is needed to obtain tangible pressure drops in the 'observational' well. In this study, we present working equations that will allow us to process field data when the flow rate at the 'active' well is a function of time. The shut-in period is also considered. A new method of field data processing, where all measured pressure drops are utilized, is proposed. The suggested method allows us to use the statistical theory to obtain error estimates on the regression parameters. It is also shown that when high precision (resolution) pressure gauges are employed, the pressure time derivative equations can be used to determine formation hydraulic diffusivity. An example is presented to demonstrate the data processing procedure.
Multiphase Flowmeter and Production Logs Diagnose Well Response in an Onshore ADCO Field, Abu Dhabi
Proceedings of Middle East Oil Show, 2003
In early 2002, Abu Dhabi Company for Onshore Oil Operations (ADCO) ran a production-logging program on a high-performance onshore well with an intensive surface welltesting program. This involved running a multiphase flow meter in combination with a calibrated gauge tank and a test separator, in order to qualify the metrological performance of the multiphase flow meter. The objectives were to determine well productivity, establish the flow profile of the reservoir, and assess the performance of the multiphase flowmeter. This paper describes the benefit of advanced multiphase flowmeter technology and the verification of its performance accuracy against production logs and surface equipment. In addition to the accuracy computations, the repeatability and linearity of each measuring device were also evaluated. Examples will be given. The paper also illustrates how this multiphase flowmeter technology improved the diagnosis of the actual well response.
Proceedings of SPE Asia Pacific Oil and Gas Conference and Exhibition, 2002
The resolution and accuracy provided by the existing technology for downhole (pressure and temperature) and rate measurements are unprecedented. However, while the potential benefits have been outlined, the models and processes required to reap these benefits (in particular the quantifiable ones) have not been sufficiently documented. In addition, considering the increasing number of reported work in this area, it is necessary to provided a framework for the analysis and discussion of existing and upcoming applications. This paper presents a: i) summary and classification of downhole and flow rate measurements applications, ii) a discussion of their benefits for reservoir description and production optimization, and iii) the models and processes required to obtain those benefits. The above-referenced applications are classified in three main areas: reservoir characterization, reservoir/well flow modeling, and process monitoring. The discussion of each application includes: benefits, previously reported work, required measurements and other relevant data, and a general description of the necessary models and processes. The paper is expected to be useful assessing the possible impact of investments (business cases) in permanent downhole and flow rate measurements, designing plans for the development or acquisition of applications, and establishing the knowledge requirements in the context of training programs.
Applied Buildup Well Test Interpretation: Field Testing of Conventional and Deconvolution Methods
SPE International Conference and Exhibition on Formation Damage Control, 2016
Well tests are typically used to evaluate formation damage before and after workovers. Buildup tests are the most commonly used transient because less flow rate measurement uncertainties leading in more reliable results, and they have a robust mathematical foundation. To take in account the flow rate history and its uncertainties several deconvolution algorithms were developed. These algorithms also are applicable to minimize the initial distortion in the reservoir's pressure response due to wellbore storage, with the expectation of improving the permeability and total skin estimated in shorter logging times. This paper presents a comparative study of conventional well test methods, and direct and indirect deconvolution techniques in several field cases. This study includes buildup tests of real-time sandface rate measurements during the after-flow period. These field cases were analyzed using conventional well test methods and three deconvolution techniques; namely, straight line approximation, material balance deconvolution, and modified "β" function. We determined that the three deconvolution methods are preferable to conventional well test methods because they require much shorter logging times; however, their reliability depends on the real-time data acquisition quality. The well tests analyzed show that we cannot rely solely on the new deconvolution techniques for well test interpretation in shorter times; however, these new methods improve the reliability in the main matching parameters, permeability and total skin, at no additional time and cost. As a result, the new methods are excellent additions to the techniques used for well test interpretation.
Well-Testing Challenges in Unconventional and Tight Gas Reservoirs
Day 5 Thu, April 26, 2018, 2018
Traditionally, newly drilled wells are tested using a drillstem test (DST) or wireline formation test (WFT) to evaluate production potential and help make development and completion decisions. These methods are typically designed to flow the well under controlled conditions and then shut in the flow to achieve a pressure buildup (PBU). Depending on how it is conducted, testing could involve a typical DST, closedchamber DST, slug test, or surge test. Later, during the life of a well, other tests, such as standard drawdown-buildup, reservoir limit, flow-after-flow, interference, and pulse tests are conducted to evaluate productivity, remaining reserves, amount of damage, depletion, and production allocation. Even though injection/falloff (IFO) is also an established testing type, it is not conducted as often as a standard pressure drawdown (PDD) and PBU test within the petroleum industry because of possible formation damage resulting from a noncompatible injection fluid. Such tests ar...
Re-analysis of hydraulic tests conducted for Well 4A
1995
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