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Xu B.,CNOOC Research Institute | Li X.,China University of Petroleum - Beijing | Xu H.,Petrochina | Haghighi M.,University of Adelaide | And 4 more authors.
Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition, APOGCE 2013: Maximising the Mature, Elevating the Young | Year: 2013

Production forecasting, well spacing, and well pattern optimization are key tasks in coal-bed methane field development plan. Desorption area around a production well is an important factor in well performance and reserve estimation. Analytical models are found to be simple and practical tools for drainage area calculation and well deliverability in conventional reservoirs. However, up to now, we have found no such analytical model for coal-bed methane wells with two-phase flow in which the gas desorption in coal is the controlling mechanism while the water is flowing in the cleat system. In this paper, we present a mathematical model to predict how the size of desorption area is changing with pressure propagation during gas and water production. The pressure profiles at different production stages are determined using diffusivity equation which is solved using the known method of "continuous succession of steady states". For the case of two-phase flow of gas-water system, the pressure squared concept is used for linearization in middle and late times, while the pressure concept is used in early times when water flow is dominated. We have combined pressure from the solution of diffusivity equation with the material balance equation in order to develop our predictive model which is applicable for vertical wells for both cases of with or without hydraulic fractures. This model is verified by numerical simulation and is in excellent agreement with the numerical solutions. Furthermore, the developed model is applied in one coal-bed methane well group in Hancheng field in China. It is found that desorption area is expanded outward in elliptical shape and the area can be calculated by the gas production data. The results show that two sample wells in the group have interfered with each other after producing for 525 days. Copyright 2013, Society of Petroleum Engineers.

Zhu Z.,CNOOC Research Institute
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

It is well known that time-lapse seismic has been taken as a powerful tool for reservoir management. But there are conditions to apply time-lapse seismic to a certain reservoir, so the feasibility analysis is the foundation of time-lapse seismic application. There are many production oil&gas fields in China offshore, which one of them is more suitable for the application of time-lapse seismic technology? In this paper, the author shows the selection of affection parameters and a feasibility analysis method using Analytic Hierarchy Process(AHP). With this method, target reservoirs can be easily chosen by queuing the calculated priority scale results. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

Xu B.-X.,CNOOC Research Institute | Bai Y.-H.,CNOOC Research Institute | Chen G.-H.,CNOOC Research Institute | Feng R.-Y.,CNOOC Research Institute
SOCAR Proceedings | Year: 2015

Production performance of shale oil and gas wells is complicated due to the uncertainty of fracture geometry and heterogeneity of reservoir properties, et al. Especially, it is difficult to link the engineer parameters such as stage, cluster, proppant, fracture fluid to well production, which is significant for fracturing design and optimization. The purpose of this study is trying to find out this link and reveal the production performance and influence factors for shale oil and gas reservoirs. A large number of analytical modeling has done and the sensitivity of production influence factors has studied. Moreover, a field case of shale oil and gas basin in US is analyzed and compared with the theoretic study results. Sensitivity study showed that the production rate increases with fracture half-length, conductivity and horizontal well length increase, while declines with the fracture spacing increases. All of the engineering parameters have optimal values. Field case stated that the influence rules of engineering parameters on production are consistent with the theoretical modeling results, but it is more complicated. It is shown that production has positive correlation with horizontal well length, and has ascending trend with stage, cluster, fracture fluid, proppant increase although it is not obvious. However, the production contribution per increment of their values will decline when they increase. In most cases, the increase of engineering parameters could not lead to production decline, and will only add the operation cost and difficulty. So in order to design the engineering parameters, the optimal value should be determined based on economic indexes. The link between fracturing parameters and fracture characteristics is significant. Fracturing monitoring or fracture propagation modeling is required and necessary to understand well performance for shale oil and gas reservoirs.

Liu C.C.,CNOOC Research Institute | Cui J.,Jilin University | Yang X.C.,CNOOC Research Institute
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

In this paper, we give the simplified P-SV wave reflection coefficient in VTI media, based on an overall consideration of two different approximate formulas of Petr Jilek. By given three models ISO/VTI models we test its accuracy. Simultaneously, this paper discusses its application in AVO attribute analysis and hydrocarbon detection. According to elastic impedance derivation method,elastic impedance equation in VTI medium is derived by the simplified P-SV wave approximate formula. Finally, we analyzes the influence of Thomsen anisotropic parameters on reflection coefficient and elastic impedance.

Jiang L.,LandOcean Energy Services Co. | Shen Y.,CNOOC Research Institute | Zhang Z.G.,LandOcean Energy Services Co. | Tang J.B.,LandOcean Energy Services Co. | And 2 more authors.
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

The geological model generated with traditional modeling method for complex lithology reservoir usually does not fit for the actual underground conditions , to solve this problem, we put forward the model optimization method in reservoir seismic inversion which based on collaborative modeling. This method updates the model step by step through multi-collaborative model and impedance inversion so that modeling phenomenon can be eliminated gradually. Consequently the ambiguity of seismic inversion will be reduced, and the reliability of the inversion is improved. By applying this method to glutenite of northern slope in Dongying Depression, the prediction results are improved to be more consistant with the logging data, the internal configuration of glutenite body can be revealed clearly, and the connection of interbedded glutenite can be ascertained.

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