Density-Based Production-Data Analysis of Gas Wells With Significant Rock-Compressibility Effects

2015 ◽  
Vol 18 (02) ◽  
pp. 205-213 ◽  
Author(s):  
Miao Zhang ◽  
Luis F. Ayala
Keyword(s):  
High Pressure ◽  
Material Balance ◽  
Production Performance ◽  
Production Data ◽  
Correct Prediction ◽  
Well Performance ◽  
Gas Wells ◽  
Rock Compressibility ◽  
Large Formation ◽  
Compressibility Effects

Summary The state-of-the-art analysis of the production performance of gas wells relies on material-balance concepts combined with pseudopressure and pseudotime for rate-time decline analysis and reserves estimations. In many cases, rock compressibility and reservoir pore-volume (PV) change are either neglected or accounted for by replacing gas compressibility with total compressibility values. In this work, we extend the applicability of a rescaled exponential and density-based decline-analysis approach (Ayala and Ye 2013a, b; Zhang and Ayala 2014a, b) for the decline analysis of gas systems experiencing significant rock-compressibility effects. We formally derive the density-based analytical techniques that rigorously capture formation-compressibility effects during the analysis of gas-well-production data during boundary-dominated flow, which proves crucially important for high-pressure and/or large-formation-compressibility gas-reservoir systems. The proposed formulation enables the calculation and correct prediction of well performance and original gas in place (OGIP) by incorporating formation compressibility and the change of reservoir PV effects, which may prove crucially important in high-pressure and/or relatively large-formation-compressibility gas reservoirs. We also present the associated straight-line analysis technique used for OGIP determination on the basis of the density approach applicable to constant-bottomhole-pressure production and variable-flow-rate/pressure-drop systems.

scholarly journals Dynamic Material Balance Method for Estimating Gas in Place of Abnormally High-Pressure Gas Reservoirs

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 1) ◽  
Author(s):  
Lixia Zhang ◽  
Yingxu He ◽  
Chunqiu Guo ◽  
Yang Yu
Keyword(s):  
High Pressure ◽  
Material Balance ◽  
Balance Method ◽  
Production Data ◽  
Reservoir Pressure ◽  
Material Balance Equation ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Material Balance Method ◽  
The Relationship

Abstract Determination of gas in place (GIP) is among the hotspot issues in the field of oil/gas reservoir engineering. The conventional material balance method and other relevant approaches have found widespread application in estimating GIP of a gas reservoir or well-controlled gas reserves, but they are normally not cost-effective. To calculate GIP of abnormally pressured gas reservoirs economically and accurately, this paper deduces an iteration method for GIP estimation from production data, taking into consideration the pore shrinkage of reservoir rock and the volume expansion of irreducible water, and presents a strategy for selecting an initial iteration value of GIP. The approach, termed DMBM-APGR (dynamic material balance method for abnormally pressured gas reservoirs) here, is based on two equations: dynamic material balance equation and static material balance equation for overpressured gas reservoirs. The former delineates the relationship between the quasipressure at bottomhole pressure and the one at average reservoir pressure, and the latter reflects the relationship between average reservoir pressure and cumulative gas production, both of which are rigidly demonstrated in the paper using the basic theory of gas flow through porous media and material balance principle. The method proves effective with several numerical cases under various production schedules and a field case under a variable rate/variable pressure schedule, and the calculation error of GIP does not go beyond 5% provided that the production data are credible. DMBM-APGR goes for gas reservoirs with abnormally high pressure as well as those with normal pressure in virtue of its strict theoretical foundation, which not only considers the compressibilities of rock and bound water, but also reckons with the changes in production rate and variations of gas properties as functions of pressure. The method may serve as a valuable and reliable tool in determining gas reserves.

Gas-Production-Data Analysis of Variable-Pressure-Drawdown/Variable-Rate Systems: A Density-Based Approach

2014 ◽  
Vol 17 (04) ◽  
pp. 520-529 ◽  
Author(s):  
Miao Zhang ◽  
Luis F. Ayala H.
Keyword(s):  
Data Analysis ◽  
Material Balance ◽  
Gas Production ◽  
Variable Pressure ◽  
Production Data ◽  
Variable Rate ◽  
Well Performance ◽  
Gas Well ◽  
Type Curves ◽  
Performance Forecasting

Summary This study demonstrates that production-data analysis of variable-bottomhole-flowing-pressure/variable-rate gas wells under boundary-dominated flow (BDF) is possible by use of a density-based approach. In this approach, governing equations are expressed in terms of density variables and dimensionless viscosity/compressibility ratios. Previously, the methodology was successfully used to derive rescaled exponential models for gas-rate-decline analysis of wells primarily producing at constant bottomhole pressure (Ayala and Ye 2013a, b; Ayala and Zhang 2013; Ye and Ayala 2013; Zhang and Ayala 2014). For the case of natural-gas systems experiencing BDF, gas-well-performance analysis has been made largely possible by invoking the concepts of pseudotime, normalized pseudotime, or material-balance pseudotime. The density-based methodology rigorously derived in this study, however, does not use any type of pseudotime calculations, even for variable-rate/variable-pressure-drawdown cases. The methodology enables straightforward original-gas-in-place calculations and gas-well-performance forecasting by means of type curves or straight-line analysis. A number of field and numerical case studies are presented to showcase the capabilities of the proposed approach.

An Integrated Model for History Matching and Predicting Reservoir Performance of Gas/Condensate Wells

2013 ◽  
Vol 16 (04) ◽  
pp. 412-422
Author(s):  
A.M.. M. Farid ◽  
Ahmed H. El-Banbi ◽  
A.A.. A. Abdelwaly
Keyword(s):  
History Matching ◽  
Material Balance ◽  
Integrated Model ◽  
Gas Condensate ◽  
Production Performance ◽  
Productivity Index ◽  
Production Data ◽  
Fluid Composition ◽  
Two Phase ◽  
Reservoir Simulator

Summary The depletion performance of gas/condensate reservoirs is highly influenced by changes in fluid composition below the dewpoint. The long-term prediction of condensate/gas reservoir behavior is therefore difficult because of the complexity of both composition variation and two-phase-flow effects. In this paper, an integrated model was developed to simulate gas-condensate reservoir/well behavior. The model couples the compositional material balance or the generalized material-balance equations for reservoir behavior, the two-phase pseudo integral pressure for near-wellbore behavior, and outflow correlations for wellbore behavior. An optimization algorithm was also used with the integrated model so it can be used in history-matching mode to estimate original gas in place (OGIP), original oil in place (OOIP), and productivity-index (PI) parameters for gas/condensate wells. The model also can be used to predict the production performance for variable tubinghead pressure (THP) and variable production rate. The model runs fast and requires minimal input. The developed model was validated by use of different simulation cases generated with a commercial compositional reservoir simulator for a variety of reservoir and well conditions. The results show a good agreement between the simulation cases and the integrated model. After validating the integrated model against the simulated cases, the model was used to analyze production data for a rich-gas/condensate field (initial condensate/gas ratio of 180 bbl/ MMscf). THP data for four wells were used along with basic reservoir and production data to obtain original fluids in place and PIs of the wells. The estimated parameters were then used to forecast the gas and condensate production above and below the dewpoint. The model is also capable of predicting reservoir pressure, bottomhole flowing pressure, and THP and can account for completion changes when they occur.

Optimization of Well Spacing for Tight Sandstone Gas Reservoirs - Case Study of Eastern Sulige Gas Field

2012 ◽  
Vol 616-618 ◽  
pp. 762-766
Author(s):  
Rui Lan Luo ◽  
Ji Wu Fan ◽  
Hong Mei Liao ◽  
Wen Xu
Keyword(s):  
Early Stage ◽  
Production Performance ◽  
Test Time ◽  
Production Data ◽  
Tight Gas ◽  
Gas Wells ◽  
Tight Sandstone ◽  
Gas Field ◽  
Gas Well ◽  
Well Spacing

Influenced by special geologic condition and stimulation, the production performance of tight fractured gas well is obviously different from that of conventional gas well. During deliverability testing, the hydraulic fractured gas well can never reach steady state with limited test time. It is difficult to calculate reserve and drainage area accurately at early development stage. Take eastern Sulige gas field for example, by correctly recognizing the percolation characteristics and production performance of hydraulically-fractured tight gas wells, and combined with core analysis, 116 hydraulically fractured tight gas wells in eastern Sulige gas field have been analyzed. A prediction chart of recoverable reserve for estern Sulige gas field is established. With this chart, the ultimately recoverable reserves, drainage sizes, drainage lengths and drainage widths of 116 hydraulically-fractured tight gas wells in eastern Sulige gas field are predicted based on early stage of production data, and finally a reasonable well spacing for this field is suggested. Only utilizing routine production data without employing additional resources, this method is a good predictive guide to launch a development plan of tight gas field.

scholarly journals An Optimization-Based Method for the Explicit Production Data Analysis of Gas Wells

2022 ◽  
Vol 9 ◽  
Author(s):  
Lixia Zhang ◽  
Yong Li ◽  
Xinmin Song ◽  
Mingxian Wang ◽  
Yang Yu ◽  
...  
Keyword(s):  
Data Analysis ◽  
Balance Equation ◽  
Gas Flow ◽  
Material Balance ◽  
Gas Production ◽  
Production Data ◽  
Variable Rate ◽  
Material Balance Equation ◽  
Gas Wells ◽  
Gas Reservoir

This work aims at the exploration of production data analysis (PDA) methods without iterations. It can overcome limitations of the advanced type curve analysis relying on the iterative calculation of material-balance pseudotime and current explicit methods reckoning on specific production schedule assumptions. The dynamic material balance equation (DMBE) is strictly proved by the integral variable substitution based on the gas flow equation under the boundary dominated flow (BDF) condition and the static material balance equation (SMBE) of a gas reservoir. We introduce the pseudopressure level function γ(p) and the recovery factor function R(p) to rewrite the DMBE in terms of observed variable Y and estimated variable Ye; then the PDA can be transformed into an optimization problem of minimizing the error between Y and Ye. An optimization-based method for the explicit production data analysis of gas wells (OBM-EPDA), therefore, is developed in the paper, capable of determining the BDF constant and gas reserves explicitly and accurately for variable rate and/or variable flowing pressure systems. Three stimulated cases demonstrate the applicability and validity of OBM-EPDA with small errors less than 1% for estimated values of both reserves and Y. Not second to previous studies, the field case analysis further proves its practicability. It is shown that the nonlinear relation of γ to R can be represented by a polynomial function merely dependent on the inherent properties of the gas production system even before sorting out the production data. The errors of observed variable Y provided by OBM-EPDA facilitate the data quality control, and the elimination of outliers not subject to the BDF condition improves the reliability of the analysis. For various gas systems producing whether at a constant rate, a constant bottomhole pressure (BHP), or under variable rate and variable BHP conditions, the proposed method gives insights into the well-controlled volume and production capacity of the gas well whether in a low-pressure or high-pressure gas reservoir, where the compressibilities of rock and bound water are considered.

The First Behind-Casing Fiber-Optic Installation in a High-Pressure High-Temperature Deep Gas Well in Oman

2022 ◽  
Author(s):  
Sultan Salim Al Shoaibi ◽  
Juan Chavez Florez ◽  
Shaima Al Farsi ◽  
Adnan Al Hinai ◽  
Alvaro Nunez ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Fiber Optic ◽  
Production Performance ◽  
Distributed Temperature Sensing ◽  
Gas Wells ◽  
Fiber Optic Cable ◽  
Gas Well ◽  
High Pressure High Temperature ◽  
The Impact

Abstract This paper discusses the first fiber-optic (FO) installation in a vertical high-pressure high-temperature deep gas well in PDO, Oman. A specially designed fiber-optic cable was successfully installed and cemented behind the production casing, which was subsequently perforated in an oriented manner without damaging the cable. This paper also describes how the fiber-optic cable was used afterwards to acquire Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) data for the purpose of hydraulic fracturing diagnostics. Fiber-optic surveillance is becoming an increasingly important activity for well and reservoir surveillance. The added complexity of the fiber-optic installation will affect the well design, which is one of the elements that requires focused attention, especially when the fiber is installed behind casing. The impact on casing design, wellhead design, perforation strategy, and logging requirements will all be discussed. In order for a well to be completed with a permanent fiber-optic cable, a few critical procedures need to be followed, including: –modifying the wellhead design to include feedthrough ports for the cable;–optimizing the cement design;–imposing strict procedures to ensure the cable is installed behind the casing without getting stuck;–changing the perforation phasing to avoid damaging the cable;–mapping the location of the cable to allow the gun string to be oriented away from the cable. The fiber-optic cable itself needed to be designed to be protected in such a way that it would not be damaged during installation and completion (perf/frac) activities. Furthermore, the cable was also optimized to improve its detectability, to aid the oriented perforation. In deep gas wells, much more than in conventional shallow water injectors or oil producers, the well integrity aspect should be given special attention. Specifically, any risks related to unwanted gas leaks, either through the control line, poor cement, or because of other design errors should be avoided. In deep gas wells, high temperature and pressure will also play a big role in the expected lifespan of the cable. Finally, the well was hydraulically fractured in four stages, using the "plug-and-perf" technique, during which DAS and DTS data were acquired continuously and across all depths of the well. The data provided valuable information on the effectiveness of each of the frac stages, it could be used to analyze screen-outs and detect out-of-zone injection, and recommendations for the optimizations of future hydraulic frac designs could be derived. The fiber-optic data were also integrated with other open-hole data for improved understanding of the reservoir performance. The next step will be to acquire repeated time-lapse DAS and DTS data for production profiling, to gain more insights of how the long-term production performance is affected by the hydraulic frac operations.

scholarly journals A Semianalytical Model for Analyzing the Infill Well-Caused Fracture Interference from Shale Gas Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sidong Fang ◽  
Yonghui Wu ◽  
Cheng Dai ◽  
Liqiang Ma ◽  
Hua Liu
Keyword(s):  
Shale Gas ◽  
Control Volume ◽  
Material Balance ◽  
Production Performance ◽  
Production Data ◽  
Model Parameters ◽  
Hydraulic Fractures ◽  
Late Time ◽  
Fracture Characterization ◽  
Proposed Model

Drilling infill well has been widely used in many plays to enhance the recovery of shale gas, but the infill well-caused fracture interference is a very important issue that should be taken into consideration. The well interference makes it difficult for the conventional models to make production predictions, fracture characterization, and production data analysis. In this paper, a semianalytical model is proposed for this purpose by discretizing the whole control volume of the parent and infill wells into several linear flow zones. In this way, three important issues can be further handled very naturally, including fracture connection between the parent and infill wells, different SRV properties for zones with different distances to the wellbore, and different production times for adjacent wellbores. The approximate expressions for different flow regimes are used in making production predictions in the time domain, and a flowing material balance method and a simple iteration are used to update the model parameters step by step. The proposed model is shown to be reasonable and accurate for handling multiwell interference problems after comparing with the commercial numerical simulator tNavigator. The synthetical cases show that the fracture parameters, SRV properties, and well infill time have a significant influence on the production performance of both the parent and infill wells. The results show that the production of the parent well will be dramatically enhanced when it is connected with the infill well via high-conductive hydraulic fractures. Longer unconnected fractures and more fracturing stages/clusters for the infill well will result in higher production for the infill well, but a negative effect is observed for the parent well. The permeability of the distant well SRV has a similar influence on the parent and infill wells. The results also show that late time well interference will result in a more significant increase in production rate on the log-log plots for the severe depletion around the parent well. Finally, the proposed model is used to analyze the production data of a field case from Fuling shale in Southwestern China. After analyzing the production data, several parameters can be obtained for both parent and infill wells, including the fracture lengths and conductivities, numbers of connected fractures, and the near and distant well permeabilities of the SRV. This gives a basic and practical technique for production prediction, formation and fracture evaluation, and well connectivity analysis from shale gas wells with fracture connection.

Prediction Method of Production Performance of Gas Well

2014 ◽  
Vol 522-524 ◽  
pp. 1547-1551
Author(s):  
Xu Zhang ◽  
Wei Hua Liu
Keyword(s):  
Prediction Models ◽  
Material Balance ◽  
Prediction Method ◽  
Production Performance ◽  
Well Performance ◽  
Gas Well ◽  
Wellhead Pressure ◽  
Performance Factors ◽  
Bottom Hole ◽  
Method Of Production

Production performance prediction is the foundations for technical and economic evaluation of production system of gas well. Based on Material Balance Equation and Back Pressure Equation, it provides two prediction models of gas well performance, for two production modes (constant production mode and constant pressure mode) separately. These models can exhibit the change of some important production performance factors with time, such as Production, Recovery Efficiency, Wellhead Pressure, Bottom Hole Pressure, Formation Pressure, etc. By examples and discussion, it can be seen that, this method for predicting production performance is feasible and reasonable. Compared with other methods, the prediction model method expands the prediction range. It can predict the whole production periods of gas well (Stable Period, Decline Period, and Pressure-increasing Period).

SYSTEM ANALYSIS OF GEOLOGICAL-AND-PRODUCTION DATA FOR PREDICTION TEMPERATURE REGIME OF GAS WELLS OPERATION USING A GEOLOGO-TECHNOLOGICAL MODEL

2015 ◽  
pp. 56-61
Author(s):  
A. V. Kustyshev ◽  
A. V. Krasovskii ◽  
E. S. Zimin ◽  
D. A. Tatarikov
Keyword(s):  
Process Parameters ◽  
Temperature Regime ◽  
System Analysis ◽  
West Siberia ◽  
Production Data ◽  
Gas Wells ◽  
Method Of Calculation ◽  
Technological Model

An algorithm has been developed, and a method of calculation of wellhead temperature in gas wells has been realized based on the geologo-technological model. The developed method enables to calculate the forecast process parameters taking into consideration the temperature regime of gas wells. The method was tested using the above mentioned model of the Cenomanian deposit of one of West Siberia fields. The results of these calculations have been later taken into account in designing the deposit development.

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