“…Pressure-controlled production can appropriately adjust the bottom hole pressure decline rate, control the increase in effective stress, and effectively avoid the reduction of fracture conductivity, to increase the long-term EUR of the gas well. Assuming that the impact of proppant elastic embedding and deformation of proppant on the width of hydraulic fractures is linearly related to the net confining pressure 18 , the expressions ( 1 ) and ( 2 ) are expressed as follows: Figure 1 Schematic diagram of crack width change 9 . …”
Due to strong stress sensitivity resulted from unconventional tight formationsit is of practical interest to formulate a reasonable pressure drawdown plan to improve gas extraction recovery. The impact of water-shale interactions on the reservoir permeability was previously ignored in the managed pressure drawdown optimization. The controlled-pressure production dynamic analysis was mostly conducted using numerical simulation, lack of rigorous theoretical support. Hence in this paper, a theoretical production prediction model was proposed and verified with HIS RTA 2015by incorporating multiple pressure drawdown mechanisms and various non-linear gas flow process. The on-site production effects dominated by two different pressure drop methods was further compared, indicating that compared to depressurization production, the production reversion can occur in the controlled pressure production process and the EUR of single well can be increased by about 30% under the control of managed pressure drawdown approach. Finally, the pressure drawdown optimization strategy was carried out on the field test from the both production effect and economic benefits, which demonstrated that the best economic solution can generally be obtained in the early stage of production. The research results can be closely linked to the on-site production practice of shale gas wells, providing insights into designing optimized production strategy scheme.
“…Pressure-controlled production can appropriately adjust the bottom hole pressure decline rate, control the increase in effective stress, and effectively avoid the reduction of fracture conductivity, to increase the long-term EUR of the gas well. Assuming that the impact of proppant elastic embedding and deformation of proppant on the width of hydraulic fractures is linearly related to the net confining pressure 18 , the expressions ( 1 ) and ( 2 ) are expressed as follows: Figure 1 Schematic diagram of crack width change 9 . …”
Due to strong stress sensitivity resulted from unconventional tight formationsit is of practical interest to formulate a reasonable pressure drawdown plan to improve gas extraction recovery. The impact of water-shale interactions on the reservoir permeability was previously ignored in the managed pressure drawdown optimization. The controlled-pressure production dynamic analysis was mostly conducted using numerical simulation, lack of rigorous theoretical support. Hence in this paper, a theoretical production prediction model was proposed and verified with HIS RTA 2015by incorporating multiple pressure drawdown mechanisms and various non-linear gas flow process. The on-site production effects dominated by two different pressure drop methods was further compared, indicating that compared to depressurization production, the production reversion can occur in the controlled pressure production process and the EUR of single well can be increased by about 30% under the control of managed pressure drawdown approach. Finally, the pressure drawdown optimization strategy was carried out on the field test from the both production effect and economic benefits, which demonstrated that the best economic solution can generally be obtained in the early stage of production. The research results can be closely linked to the on-site production practice of shale gas wells, providing insights into designing optimized production strategy scheme.
“…The outlet flow through nozzles is mainly adjusted to control the production pressure difference and alleviate the stress sensitivity damage to reservoirs. 11 According to the bottom hole flow pressure drawdown management approaches, the production behavior of shale gas wells can be divided into depressurization production and controlled pressure production. Among them, depressurization production means that there is no flow restriction at the wellhead, and the bottom hole flow pressure in the initial production stage is rapidly reduced to the constant pressure of the gas well.…”
Section: Introductionmentioning
confidence: 99%
“…During the production practice for shale gas formations, selecting a suitable production strategy is conducive to the production decline rate reduction and the optimal cumulative production of shale gas reservoirs. The outlet flow through nozzles is mainly adjusted to control the production pressure difference and alleviate the stress sensitivity damage to reservoirs . According to the bottom hole flow pressure drawdown management approaches, the production behavior of shale gas wells can be divided into depressurization production and controlled pressure production.…”
Section: Introductionmentioning
confidence: 99%
“…The shale gas production practice shows that the EUR per well by the pressure drop-controlled production strategy can generally increase by 28–30% , compared to that by the depressurized production approach. Due to the high-pressure formation conditions and strong pressure-sensitivity effect, the Changning–Weiyuan and the Haynesville shale gas demonstration adopt controlled pressure production methods for enhancing the ultimate cumulative production.…”
Section: Introductionmentioning
confidence: 99%
“…The shale gas production practice shows that the EUR per well by the pressure drop-controlled production strategy can generally increase by 28–30% , compared to that by the depressurized production approach. Due to the high-pressure formation conditions and strong pressure-sensitivity effect, the Changning–Weiyuan and the Haynesville shale gas demonstration adopt controlled pressure production methods for enhancing the ultimate cumulative production. On the contrary, shale reservoirs with relatively low reservoir pressure coefficients such as the Fuling shale gas field and the Barnett and Marcellus shale reservoirs usually use depressurized production and the large differential pressure production method.…”
The
flow capacity of shale gas reservoirs is easily impaired during
the depletion process due to strong stress sensitivity. Thereby, an
adequate production system, namely, the managed pressure drop method,
has been widely introduced to the industrial practice application
by decelerating the wellbore pressure drop rate and ultimately improving
the long-term production process. This work presents a review of the
pressure drawdown management mechanisms for shale gas formations.
However, clarifying the water–shale interaction physical chemistry
process and developing a mathematical model that accurately describes
the water–shale interaction mechanism remain a challenge. Moreover,
different classifications of the managed production simulation research
approaches are discussed in detail. Each approach has its own merits
and demerits. Among them, numerical simulations are commonly seen
in cognizance of characterizing the managed pressure drawdown production
period but are found to be relatively time-consuming and also computationally
expensive. An optimized theoretical model is therefore essential because
it can lead to a precise estimation of the ultimate long-term production
and capture instantaneously the actual shale gas reservoir depletion
phenomenon with various production systems compared to other available
methods. The key influence of managed pressured production for single
wells in shale reservoirs is elaborated as well. As observed from
the current review, an accurate description of the pressure drop management
mechanism is crucial for the theoretical model of the pressure control
production process for shale gas wells. The influence of water–rock
interaction on the managed pressure drawdown mechanism cannot be ignored.
There have thus been works to improve and enhance it for use in theoretical
models for shale formations. On the other hand, the advancement of
theoretical models presents an opportunity for better representation
of the managed pressure drop production process.
The influence of geological and engineering factors results in the complex production characteristics of shale gas wells. The productivity evaluation method is effective to analyze the production decline law and estimate the ultimate recovery in the shale gas reservoir. This paper reviews the production decline method, analytical method, numerical simulation method, and machine learning method. which analyzes the applicable conditions, basic principles, characteristics, and limitations of different methods. The research found that the production decline method can mainly account for the gas well production and pressure data by fitting type curve analysis. The analytical method is able to couple multiple transport mechanisms and quantify the impact of different mechanisms on shale gas well productivity. Numerical simulation builds multiple pore media in shale gas reservoirs and performs production dynamics as well as capacity prediction visually. Machine learning methods are a nascent approach that can efficiently use available production data from shale gas wells to predict productivity. Finally, the research discusses the future directions and challenges of shale gas well productivity evaluation methods.
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