General Coning Correlations Based on Mechanistic Studies

Lee, S.H.; Tung, W. B.

doi:10.2118/20742-ms

Cited by 10 publications

(8 citation statements)

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“…The results and understanding acquired from this study offer insights into the development of bottom water reservoirs. In contrast to the critical rate, the prediction of breakthrough time (2,5) and post breakthrough performance (6,7) have been found to be more important in a practical sense because water coning appears to be inevitable in a bottom water reservoir. They observed that water coning is a rate-sensitive process and determined the critical oil rate, which is the maximum water-free production rate, by neglecting the shape of the cone.…”

Section: Introductionmentioning

confidence: 99%

An Insight Into Development of Bottom Water Reservoirs

Zhao

Liu

2006

Journal of Canadian Petroleum Technology

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While water production is an inevitable consequence in bottom water reservoirs, it is usually desirable to defer the onset or the rise of water coning as long as possible. Numerous mechanical and chemical methods have been applied to achieve this goal over recent decades. This paper presents new insights into improving oil production and reducing water production by considering flow barriers below horizontal well trajectories in formation regions with low permeabilities, especially natural ones such as shale bodies. A 3D numerical simulation that applies the Computer Modelling Group's (CMG) STARS Simulator as a cost-effective way to investigate the effects of barriers on horizontal well performance in a bottom water reservoir has been conducted. More specifically, the effects of permeability, dimension, and position of barriers have been comprehensively analyzed when a horizontal well is implemented as a producer. The simulation results have shown that if barriers exist below a horizontal producer, water cut can be postponed and reduced greatly, and cumulative oil production can be increased. Cumulative water production can be decreased dramatically as well. To broaden the applicability of this new insight, some of the possible field implementing technologies, including fractured horizontal wells, small-scale CO2 injection, and solvent injection, are qualitatively simulated to determine their applicability for developing heavy oil in bottom water reservoirs using horizontal wells with the presence of barriers. The simulation results have shown that much better well performance can be reached with the help of barriers when these technologies are integrated systematically. This new strategy shows a rather promising and economic way to develop bottom water reservoirs where the natural driving energy of the aquifer could benefit the oil production process. The results and understanding acquired from this study offer insights into the development of bottom water reservoirs. Introduction Water coning is a critical issue for conventional vertical well production in bottom water reservoirs. Generally speaking, the fluid production process creates a low-pressure region around the wellbore in the reservoir. This differential pressure causes the oilwater interface to deform into a cone shape, at which time the less viscous water phase is produced in preference to the more viscous oil phase. Consequently, the producing Water-Oil Ratio (WOR) increases quickly and readily reaches an uneconomic level. Darcy's law is still the fundamental principle behind this phenomenon. In the past, many researchers have conducted experimental, analytical, and numerical studies on water coning behaviour in vertical wells. Muskat and Wyckoff(1) published one of the early studies related to water coning in 1935. They observed that water coning is a rate-sensitive process and determined the critical oil rate, which is the maximum water-free production rate, by neglecting the shape of the cone. Later on, researchers(2, 3) directed their studies toward the calculation of the critical oil rate. Guo and Lee(4) indicated that the critical rate does not occur at zero wellbore penetration, as may intuitively be expected, but at a wellbore penetration of about one-third of the total oil-zone thickness for an isotropic reservoir.

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Section: Introductionmentioning

confidence: 99%

An Insight Into Development of Bottom Water Reservoirs

Zhao

Liu

2006

Journal of Canadian Petroleum Technology

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“…While the well testing cannot be conducted in certain time intervals, this method cannot be applied to every single well for a good prediction. Recently, rate transient analysis (RTA) gets rapid development in the studies of reserves evaluation and reservoir characterization (Kuo et al, 1983;Lee and Tung, 1990;Moran, 2004;Elahmady and Wattenbarger, 2007;Tao et al, 2003;Blasingame et al, 1991;Mattar and McNeil, 1998;Li et al, 2016). Using RTA in water invasion prediction is still in its infancy (Agarwal et al, 1998;Denney, 2005;Iik et al, 2010;Li et al, , 2010F.A.S.T, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, assessment of water breakthrough risk in gas wells were confined to the prediction of water breakthrough time and the evaluation of aquifer influx (Yang et al, 2013;Kang et al, 2004;Fan et al, 2012;Li et al, 2012;Hu et al, 2012;Kuo et al, 1983;Lee and Tung, 1990). The water breakthrough time is defined by water coning breakthrough time.…”

Section: Introductionmentioning

confidence: 99%

New Method of Water Influx Identification and Ranking for a Super-Giant Aquifer Drive Gas Reservoir

Xia

et al. 2015

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For gas reservoirs with strong bottom or edge aquifer support, the most important thing is to avoid water breakthrough in gas well. Because water breakthrough in gas wells can explicitly reduce well productivity and reservoir recovery. Therefore, how to identify aquifer influx of gas wells are urgent in order to guide the well production rate optimization and improve gas field performance.This paper provides a new method with 3 diagnostic curves to identify aquifer influx status for gas wells, which are mainly based on well production and pressure data. And the whole production period of gas wells can be classified into 3 periods based on the diagnostic curves: no aquifer influx period, early aquifer influx period, middle-late aquifer influx period. And a suite of index with both static and dynamic description understanding are established for aquifer influx identification and ranking. Also how to use the index to identify aquifer influx are illustrated.This new method has been used for evaluation of all gas wells in Kela 2 gas field. It is one of the biggest abnormal high pressure gas field in the world, which is of high gas column, high productivity of a single well and strong aquifer support. Until now 2 of 17 production wells have been water-breakthrough and risks of water breakthrough for other wells are increasing. Water breakthrough sequence of all wells in Kela 2 gas field are determined based on 12 aquifer influx index evaluation by analytical hierarchy process and fuzzy evaluation method. Then all wells are ranked into 4 types based on evaluation results: water breakthrough wells, wells in middle-late aquifer influx period, wells in early aquifer influx period, and no aquifer influx wells. Actual gas well performance validate this new method. Then evaluation results are applied to well production rate optimization. In order to keep the whole gas field production rate, production rate of wells in middle-late aquifer influx period are decreased, while production rate of no aquifer influx wells are increased. Finally gas field performance are explicitly improved. This paper offers a new method and a case study of aquifer influx identification and ranking for aquifer drive gas reservoir. It also provides a methodology and reference case for engineers to develop other similar gas fields.

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“…Correlations developed for homogeneous reservoirs consider the effect of vertical permeability in the form of vertical permeability to horizontal permeability ratio ( K v / K h ). Presence of shale seals and compaction phenomenon lower the vertical permeability . However, there are cases such as naturally fractured reservoirs (NFRs) where the K v / K h is generally higher than one .…”

Section: Introductionmentioning

confidence: 99%

Estimation of breakthrough time for water coning in fractured systems: Experimental study and connectionist modeling

et al. 2014

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in Wiley Online Library (wileyonlinelibrary.com) Water coning in petroleum reservoirs leads to lower well productivity and higher operational costs. Adequate knowledge of coning phenomena and breakthrough time is essential to overcome this issue. A series of experiments using fractured porous media models were conducted to investigate the effects of production process and pore structure characteristics on water coning. In addition, a hybrid artificial neural network (ANN) with particle swarm optimization (PSO) algorithm was applied to predict breakthrough time of water coning as a function of production rate and physical model properties. Data from the literature combined with experimental data generated in this study were used to develop and verify the ANN-PSO model. A good correlation was found between the predicted and real data sets having an absolute maximum error percentage less than 9%. The developed ANN-PSO model is able to estimate breakthrough time and critical production rate with higher accuracy compared to the conventional or back propagation (BP) ANN (ANN-BP) and common correlations. The presence of vertical fractures was found to accelerate considerably the water coning phenomena during oil production. Results of this study using combined data suggest the potential application of ANN-PSO in predicting the water breakthrough time and critical production rate that are critical in designing and evaluating production strategies for naturally fractured reservoirs.

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General Coning Correlations Based on Mechanistic Studies

Cited by 10 publications

References 8 publications

An Insight Into Development of Bottom Water Reservoirs

An Insight Into Development of Bottom Water Reservoirs

New Method of Water Influx Identification and Ranking for a Super-Giant Aquifer Drive Gas Reservoir

Estimation of breakthrough time for water coning in fractured systems: Experimental study and connectionist modeling

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