Interference Test in Naturally Fractured Formation Gas Field Case Study

Vasil'ev, Iu M; Aleksakhin, Yu.I.

doi:10.2118/181969-ms

Cited by 3 publications

(1 citation statement)

References 8 publications

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“…A fractured reservoir can be characterized by a multimedium model or discrete fracture model depending on the density of fractures. Kazemi and Deruyck analyzed the interference test of double porosity medium reservoirs using the Warren-Root model for reservoirs with intensive fractures [28][29][30]. The multimedium model does not work for reservoirs with sparse fractures.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Interference Test for Wells Connected by a Large Fracture

Han

Liu

et al. 2019

Applied Sciences

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Pressure communication between adjacent wells is frequently encountered in multi-stage hydraulic fractured shale gas reservoirs. An interference test is one of the most popular methods for testing the connectivity of a reservoir. Currently, there is no practical analysis model of an interference test for wells connected by large fractures. A one-dimensional equation of flow in porous media is established, and an analytical solution under the constant production rate is obtained using a similarity transformation. Based on this solution, the extremum equation of the interference test for wells connected by a large fracture is derived. The type-curve of pressure and the pressure derivative of an interference test of wells connected by a large fracture are plotted, and verified against interference test data. The extremum equation of wells connected by a large fracture differs from that for homogeneous reservoirs by a factor 2. Considering the difference of the flowing distance, it can be concluded that the pressure conductivity coefficient computed by the extremum equation of homogeneous reservoirs is accurate in the order of magnitude. On the double logarithmic type-curve, as time increases, the curves of pressure and the pressure derivative tend to be parallel straight lines with a slope of 0.5. When the crossflow of the reservoir matrix to the large fracture cannot be ignored, the slope of the parallel straight lines is 0.25. They are different from the type-curves of homogeneous and double porosity reservoirs. Therefore, the pressure derivative curve is proposed to diagnose the connection form of wells.

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Section: Introductionmentioning

confidence: 99%

Investigation on Interference Test for Wells Connected by a Large Fracture

Han

Liu

et al. 2019

Applied Sciences

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A Novel Multi-Well Interference Testing Model of a Fractured Horizontal Well and Vertical Wells

Cheng

Qin

et al. 2018

SPE Annual Technical Conference and Exhibition

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High water-cut has been observed for many multi-fractured horizontal wells (MFHWs) in China soon after waterflooding begins. Available well-testing models of single well ignored the effect of adjacent wells on the MFHW, and they are unable to evaluate whether MFHW (producer) and surrounding vertical wells (injectors) are in good pressure communication. To fill this gap, this work presents a multi-well interference testing (MWIT) model to consider the interference of injectors and further match the interference pressure data. The MWIT model is established to investigate the effect of multiple injection wells on transient-pressure behavior of the MFHW. Due to the interferences from injectors, the pressure and pressure-derivative curves of MWIT move down beginning with the biradial flow regime for single MFHW model, and pseudo-radial flow (horizontal line with the value of 0.5 on pressure-derivative curve) disappears. Sensitivity analysis was conducted to discuss the effects of crucial parameters on the pressure response, including total injection rates, unequal injection rates of injectors, well spacing, injector distribution, number and production of hydraulic fractures. When total injection rates are lower than the production rate, the pressure derivative will eventually stabilize at 0.5*(1-Σ(qIncjD)) during the interference-flow regime on the log-log type curves. Since only the positive number can be shown in the log-log graph, semi-log curves are also developed to fully characterize the flow regimes of MWIT. A novel finding is that pressure derivative also ultimately behave as a horizontal line with the value of 0.5*(1-Σ(qIncjD)) when total injection rates are equal or higher than production rates on the semi-log curves. The total injection rates and well spacing between the MFHW and injectors have a significant effect on middle and late pressure behaviors, whereas the number and production of fractures mainly affects the pressure responses during early to middle period. Type curves indicate that the effect of surrounding injectors are significant and cannot be ignored, and the novel characteristics provide potential application of the MWIT model to estimate formation parameters. Case studies highlight the application of the proposed method in effectively matching the interference pressure data. Interference-testing analysis of the MWIT provides a better reservoir evaluation compared to single-well testing model.

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A New Methodology for Naturally Fractured Reservoir Characterization: Use of Multi-Well Interference Tests Interpretation

Vincent¹,

Portier²

2020

SPE Europec

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Reservoir characterization is a key aspect during the appraisal and production phases of a field development. Understanding the reservoir property distribution and dynamic behavior reduces uncertainties and helps to improve recovery while optimizing investments. Modern seismic and logging tools, combined with core data, provide multi-disciplinary teams with better data quality. However, the reservoir heterogeneity and connectivity, often remain uncertain until several years of production have been achieved. This is true of naturally fractured reservoirs, for which fracture connectivity can only be characterized dynamically. In order to provide earlier dynamic connectivity information in a field development, interference tests have been developed to define whether parts of a reservoir are in communication, and to estimate reservoir properties between wells which is not possible from log measurements and correlations. Interference tests are ideally conducted when a reservoir is in equilibrium with homogeneous and fully stabilized pressure through the entire field. This paper describes a new methodology for interference test interpretation when reservoir pressure is not stabilized, and also describes how to optimize multi-well interference operation sequencing. First, the observation well is tested, and second, active wells are produced in a sequence while the observation well bottom hole pressure (BHP) is still building up. Pressure changes only related to the interference are extracted from the pressure measurements at the observation well by removal of the build-up effects. Interpretation is subsequently performed to quantify reservoir properties such as matrix and fracture permeability and porosity to match interference time lag (also named time of flight), pressure and depletion amplitude. Permeability anisotropy and fracture connectivity are defined and quantified at the field scale. The application of this new methodology to multi-well interference tests performed on a naturally fractured gas reservoir is presented in this paper. Using this methodology can prove connectivity through open natural fractures and quantify the fracture network properties even when there is a very small interference amplitude. Defining the extent of a natural fracture network and its contribution to the hydrocarbon production is crucial for naturally fractured reservoir development and reservoir management. In addition the described methodology was applied to calculate gas volumes dynamically connected to the wells. The capability to interpret an interference test performed while the pressure measured at the observation well is still building up allows a significant operational time and cost reduction while ensuring accurate interpretation of reservoir parameters. This methodology can be applied to an interference test including a well pair or multiple wells.

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Interference Test in Naturally Fractured Formation Gas Field Case Study

Cited by 3 publications

References 8 publications

Investigation on Interference Test for Wells Connected by a Large Fracture

Investigation on Interference Test for Wells Connected by a Large Fracture

A Novel Multi-Well Interference Testing Model of a Fractured Horizontal Well and Vertical Wells

A New Methodology for Naturally Fractured Reservoir Characterization: Use of Multi-Well Interference Tests Interpretation

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