Computing Flowing Bottom-Hole Pressure from Wellhead Pressure

2003 ◽  
pp. 748-751
2013 ◽  
Vol 37 ◽  
pp. 3291-3298 ◽  
Author(s):  
Mingze Liu ◽  
Bing Bai ◽  
Xiaochun Li

2021 ◽  
Author(s):  
Satoshi Maki

Abstract Shut-in bottom-hole pressure (SIBHP) is key information to monitor reservoir depletion and thus to evaluate gas in place for a gas field. Permanent downhole gauges are widely used to continuously measure bottom-hole pressure especially for subsea wells. However, when gauges fail, a large cost of workover for gauge replacement is a major problem. In case of the gauge failure, SIBHP hence needs to be estimated from measured surface data such as wellhead pressure (WHP) and wellhead temperature (WHT). The use of WHT for subsea wells however leads to a large error of the SIBHP calculation because sea current significantly affects WHT readings during shut-in. This study aims to develop a correlation methodology to predict SIBHP from surface data without using WHT. We have developed a linear correlation of hydrostatic pressure loss during shut-in with superposition time to predict SIBHP from WHP. Using superposition time of well production status with zero or one indicator effectively accounts for transient behaviour of hydrostatic pressure loss caused by cooling of wellbore fluid and pressure build-up. The transient behaviour differs by individual wells. Hence, the coefficients of the correlation were calibrated well by well to reproduce observed SIBHP. The correlations were applied to the Ichthys gas-condensate field located in the Browse Basin, North West Shelf of Australia. SIBHP trends are reasonably reproduced by the correlations after calibration. A blind test was performed using additional 18 months production data to investigate the predictability of the proposed correlation. As a result, high accuracy of the prediction is confirmed with an average absolute error of approximately 0.4% for the test period. The SIBHP of wells in which downhole gauges have failed is predicted by the calibrated correlations, and the predicted SIBHP is utilised for the reservoir management of the Ichthys field. We present the novel methodology to predict SIBHP from observed surface data without WHT for subsea gas-condensate wells considering the transient behaviour of hydrostatic pressure loss. The proposed correlation provides accurate prediction of SIBHP in case of the gauge failure.


2020 ◽  
pp. 014459872096415
Author(s):  
Jianlin Guo ◽  
Fankun Meng ◽  
Ailin Jia ◽  
Shuo Dong ◽  
Haijun Yan ◽  
...  

Influenced by the complex sedimentary environment, a well always penetrates multiple layers with different properties, which leads to the difficulty of analyzing the production behavior for each layer. Therefore, in this paper, a semi-analytical model to evaluate the production performance of each layer in a stress-sensitive multilayer carbonated gas reservoir is proposed. The flow of fluids in layers composed of matrix, fractures, and vugs can be described by triple-porosity/single permeability model, and the other layers could be characterized by single porosity media. The stress-sensitive exponents for different layers are determined by laboratory experiments and curve fitting, which are considered in pseudo-pressure and pseudo-time factor. Laplace transformation, Duhamel convolution, Stehfest inversion algorithm are used to solve the proposed model. Through the comparison with the classical solution, and the matching with real bottom-hole pressure data, the accuracy of the presented model is verified. A synthetic case which has two layers, where the first one is tight and the second one is full of fractures and vugs, is utilized to study the effects of stress-sensitive exponents, skin factors, formation radius and permeability for these two layers on production performance. The results demonstrate that the initial well production is mainly derived from high permeable layer, which causes that with the rise of formation permeability and radius, and the decrease of stress-sensitive exponents and skin factors, in the early stage, the bottom-hole pressure and the second layer production rate will increase. While the first layer contributes a lot to the total production in the later period, the well bottom-hole pressure is more influenced by the variation of formation and well condition parameters at the later stage. Compared with the second layer, the scales of formation permeability and skin factor for first layer have significant impacts on production behaviors.


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