Axial Fracture Initiation During Diagnostic Fracture Injection Tests and Its Impact on Interpretations

Cai, Yuzhe; Taleghani, Arash Dahi

doi:10.1007/s00603-021-02598-6

Cited by 3 publications

(3 citation statements)

References 35 publications

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“…The assumptions are as follows: each component in the gas reservoir is homogeneous. The fluid properties at any time are determined by the formation pressure, and the pressure is in equilibrium at all places (Cai and Dahi Taleghani, 2021). The formation temperature is constant temperature.…”

Section: Materials Balance Theoretical Model Of the Gas Reservoirmentioning

confidence: 99%

Review about evaluation methods of recoverable reserves of deep water drive gas reservoirs in China

Sun,

Dai,

Wang

et al. 2024

Front. Energy Res.

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It has been widely accepted that China is one of the biggest natural gas consumers. Related to the imports of LNG, China stands in a very uncomfortable situation. Most domestic gas reservoirs fall within deep water drive gas reservoirs inordinately, which has entered the production depletion stage. Accurate estimation of SEC recoverable reserves of deep water drive gas reservoirs is of great significance for gas consumption planning and peak shaving. The existing calculation methods of recoverable reserves mainly consist of static methods and dynamic methods. In the early stage of exploration and development, the volumetric method has often been utilized to calculate the recoverable reserves. With the continuous development of gas reservoirs, the main methods for evaluation are dynamic methods, including the successive subtraction of production method, water drive curve method, prediction model method, attenuation curve method, improved virtual curve method, and material balance method for deep gas reservoirs.

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Section: Materials Balance Theoretical Model Of the Gas Reservoirmentioning

confidence: 99%

Review about evaluation methods of recoverable reserves of deep water drive gas reservoirs in China

Sun,

Dai,

Wang

et al. 2024

Front. Energy Res.

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“…G-function derivative analysis requires a plot that includes the bottom-hole pressure, the pressure derivative (dP/dG), and the superimposed pressure derivative (GdP/dG). The characteristic curved shape of the pressure derivative and the superposition pressure derivative is used to identify the leak-off behaviour, of which there are four common types, i.e , normal leak-off behaviour, pressure-dependent leak-off from opened natural fractures, fracture-height recession during shut-in, and fracture-tip extension (McLellan and Janz, 1991; Barree and Mukherjee, 1996; Craig et al, 2000; Chipperfield, 2006; Cai and Dahi Taleghani, 2021). Plahn et al (1997) proposed a numerical model of the fracture pump-in and flow-back test, which gives a better estimate of fracture closure pressure than the aforementioned conventional methods.…”

Section: Introductionmentioning

confidence: 99%

“…No reduction in the accuracy of the leak-off coefficient when compared to the recorded pressure data was found. Cai and Dahi Taleghani (2021) numerically investigated the inititation and closure behaviour of an axial fracture during DFIT, and the results show that the closure time of the axial fracture from fracture compliance based DFIT analysis is earlier than that of the transverse fracture. They recommend that the combined method of the G × dP/dG plot and the dP/dG plot is helpful for DFIT interpretation.…”

Section: Introductionmentioning

confidence: 99%

Complex Fracture Closure Pressure Analysis During Shut-in: A Numerical Study

Wang

et al. 2022

Energy Exploration & Exploitation

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Conventional fracture closure models typically assume homogeneous formation. This assumption renders complex fracture closure pressure analysis during shut-in insufficient at present. In this paper, we use a cohesive zone method (CZM)-based finite element model to obtain the fracture closure pressure and minimum horizontal principal stress of the major fracture and the branch fracture based on pressure fall-off analysis. Key factors including leak-off rate, injection time, and stress anisotropy are discussed in detail. A quantitative relationship between fracture closure pressure and these factors is plotted to reduce or eliminate the errors caused by conventional fracture injection diagnostic models. The results show that leak-off rate, injection time, and stress anisotropy have a significant effect on the fracture closure process. Fracture closure in naturally fractured formations is a slow process, and the early closure pressure represents the closure of the branch fracture, which is much higher than the minimum horizontal stress. This investigation provides new insight into how to estimate the in-situ stress in naturally fractured reservoirs.

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Flowback Rates for Pump-In/Flowback Test

Wang,

Dahi Taleghani,

Cai

2024

SPE Journal

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Summary The pump-in/flowback test (PIFT), often referred to as the diagnostic fracture injection test (DFIT) with flowback, offers notable advantages in terms of time efficiency and accuracy, particularly in the context of low-permeability formations. The key to the success of this test lies in the careful selection of an optimal flowback rate to yield meaningful results. The fundamental assumption underlying the pressure analysis of these tests is the uniform closure of fractures during the flowback phase, which is considered the default fracture closure mode in current analyses. In this study, we present evidence that challenges the validity of this assumption, highlighting instances where unsuitable flowback rates can lead to nonuniform fracture closure and result in abnormal pressure data. To address this challenge, we identify different closure modes through the signature of fracture closure in the excessive bottomhole pressure decline curve. Subsequently, we propose an optimal range of flowback rates using a scaling analysis approach to obtain a uniform closure mode in an extended openhole section of a vertical well. Our method has been rigorously validated through 3D numerical simulations and field studies, enhancing its reliability and applicability. This approach helps operators to conduct effective tests in complex situations, overcoming a barrier to widespread test application.

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Axial Fracture Initiation During Diagnostic Fracture Injection Tests and Its Impact on Interpretations

Cited by 3 publications

References 35 publications

Review about evaluation methods of recoverable reserves of deep water drive gas reservoirs in China

Review about evaluation methods of recoverable reserves of deep water drive gas reservoirs in China

Complex Fracture Closure Pressure Analysis During Shut-in: A Numerical Study

Flowback Rates for Pump-In/Flowback Test

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