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Productivity and injectivity of horizontal wells. Quarterly report, October 1--December 31, 1993

Description: A number of activities have been carried out in the last three months. A list outlining these efforts is presented below followed by brief description of each activity in the subsequent sections of this report: Progress is being made on the development of a black oil three-phase simulator which will allow the use of a generalized Voronoi grid in the plane perpendicular to a horizontal well. The available analytical solutions in the literature for calculating productivity indices (Inflow Performance) of horizontal wells have been reviewed. The pseudo-steady state analytic model of Goode and Kuchuk has been applied to an example problem. A general mechanistic two-phase flow model is under development. The model is capable of predicting flow transition boundaries for a horizontal pipe at any inclination angle. It also has the capability of determining pressure drops and holdups for all the flow regimes. A large code incorporating all the features of the model has been programmed and is currently being tested.
Date: March 10, 1993
Creator: Fayers, F. J.; Aziz, K. & Hewett, T. A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, July 1, 1993--September 30, 1993

Description: A number of research activities have been carried out in the last three months. A list outlining these efforts is presented below followed by brief description of each activity in the subsequent sections of this report: (1) The available analytical solutions in the literature for steady state critical rates of horizontal wells are examined. Application of these methods to a cresting example show significant uncertainties in prediction of critical rates. (2) Sensitivity computations have been run for evaluating the effects of shale distribution on the performance of horizontal wells in heterogeneous reservoirs. (3) A number of single phase (water and oil) and two-phase (water and air) experiments have been completed in the Marathon Wellbore Model and the collected data are being analyzed. (4) A presentation of our project was given in the International Technology Forum DEA-44/67 on Horizontal, Slimhole, and Coiled Tubing, held by Maurer. (5) Our draft review report entitled ``Opportunities for Horizontal Wells and Problems in Predicting Their Performance`` has been completed.
Date: December 1, 1993
Creator: Fayers, F. J.; Aziz, K. & Hewett, T. A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, April 1, 1995--June 30, 1995

Description: The following activities have been carried out in the last three months: Work on developing a three-dimensional Voronoi grid simulator is progressing. Extensive testing of the grid generation and visualization modules of the simulator is continuing while modifications and improvements are being made to these capabilities; The recently developed semi-analytical method for calculating critical cresting rates is being extended for the case of simultaneous gas and water coning toward a horizontal well; The accuracy of available correlations and analytical models for breakthrough times of horizontal wells is being investigated through simulations of a field case; Work on developing methods for coupling between reservoir and the werbore through a network modeling approach is progressing. The current stage of the study involves evaluation of available analytical methods; The necessary modifications have been made to the rig at the Marathon facility and the high rate two-phase flow experiments are about to commence; new correlations for wall friction and interfacial friction factors have been developed for the stratified flow in horizontal and inclined pipes. After further testing this new approach will be used in our mechanistic model; and this quarterly report has been entirely devoted to the task fisted in the last item above and we only present an abridged version of the Masters report of Mr. Liang-Biao Ouyang on which it is based. The complete study will be included in the next Annual Report of the Project.
Date: August 1, 1995
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, July 1--September 30, 1995

Description: During this quarter the authors have extended their earlier semi-analytical method for determining critical cresting rates in horizontal wells to the case of both water and gas cresting. The method and the procedure will be briefly described below. They also show the application of the method to an example problem and compare the results with direct numerical simulation.
Date: November 1, 1995
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, April 1--June 30, 1996

Description: A number of activities have been carried out during this quarter of research. A list outlining these efforts is presented including: (1) The design and planning of the next phase of the two-phase flow experiments have moved forward. The necessary modifications to allow the use of wire-wrapped screens have been made. The flow loop and the data acquisition system are currently being tested and the new experiments are about to commence. (2) Work on obtaining exact well models for a horizontal well or a well of any general profile has continued. (3) Work on the application of horizontal wells in gas condensate reservoirs has progressed. The available methods and models are being critically evaluated with the aid of simulation runs. (4) Research work on developing coarse grid methods to study cresting in horizontal wells has continued. Correlations for optimum grid size, breakthrough time, and post breakthrough behavior (i.e. water-oil ratio) are being developed and tested for the problem of water cresting. (5) The Ph.D. project on three-dimensional flexible grid simulator (FLEX) was successfully defended in June. The FLEX simulator will be used in future studies as well as in future developments. The dissertation report will be submitted soon to the US DOE. This quarterly report is based on the last activity listed above. It shows the advantage of the new flexible grid simulator.
Date: August 1, 1996
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Coorelations for cresting behavior in horizontal wells. Quarterly report, October 1, 1996--December 31, 1996

Description: The following activities have been carried out in the last three months. (1) The fourth review meeting of the Horizontal Well Industrial Affiliates Program was held on October 10-11 at Stanford. The meeting was well attended and well received. In addition to the project presentations, a number of member presentations were also made at the meeting. (2) Draft plans for the continuation of the two-phase flow experiments were drawn up and sent to Marathon and other members for their review and comments. Series of new experiments with and without the wire wrapped screens used in 1996 are being considered for 1997. (3) Work on the application of horizontal wells for producing gas condensate reservoirs was continued. After verification of the black oil formulation, emphasis is being put on the compositional case where simulation runs have been set up to check the results against a semi-analytical solution. (4) The previous work on the effects of heterogeneities on horizontal well performance was continued and a paper on the subject was completed. Future work in this area will deal with a careful analysis of the interaction of heterogeneity and production performance. (5) Research work on developing coarse grid methods to study cresting in horizontal wells was continued. The previous correlations for optimum grid size, breakthrough time, and post breakthrough behavior (i.e., water-oil ratio) were further tested and optimized. Procedures to derive pseudo-functions either using numerical correlations or coarse grid simulations have been proposed and successfully tested.
Date: December 31, 1996
Creator: Aziz, K. & Hewett, T. A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, July 1--September 30, 1996

Description: This quarterly report reports on the efforts on Task 2, effects of reservoir heterogeneities on performance prediction of horizontal wells. Performance prediction of horizontal and non-conventional wells based on both analytical and numerical tools rarely match actual performance. Even a history matched case with sufficient production data fails to give reliable predictions for long times. In this study the authors explore reasons for the inability of predictive tools to make accurate predictions. They consider a case where a vertical well has been drilled and cored. Then, they generate twenty consistent geostatistical descriptions of permeability and porosity that are all constrained to hard data obtained from the vertical well. Simulations with these realizations show large differences in production rate, WOR and GOR predictions as a result of variations in reservoir properties. It is also shown that the effect of well index (WI) on simulation results is large. Furthermore, for the example considered, analytical models for critical rate and productivity calculations were found to have limited practical use.
Date: December 31, 1996
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, October 1--December 31, 1996

Description: This report describes progress on Tasks 1 and 4, Correlations for cresting behavior in horizontal wells. Research work on developing coarse grid methods to study cresting in horizontal wells was continued. The previous correlations for optimum grid size, breakthrough time, and post breakthrough behavior (i.e., water-oil ratio) were further tested and optimized. Procedures to derive pseudo-functions either using numerical correlations or coarse grid simulations have been proposed and successfully tested. The results reported here and other calculations show that the correlations developed in this work can be applied to a wide range of conditions for predicting the water break-through time (BT) and the water-oil-ratio (PBB) for horizontal wells. All of the correlations are based on the assumption of two-phase, two-dimensional flow in homogeneous reservoirs.
Date: January 30, 1997
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Annual report, March 10, 1996--March 9, 1997

Description: Progress is reported on the following tasks: advanced modeling of horizontal wells; heterogeneous effects of reservoirs; development of improved methods for calculating multi-phase pressure drops within the wellbore; pseudo-functions; development of multi-well models;testing of HW models with field examples; enhanced oil recovery applications; and application studies and their optimization.
Date: June 1, 1997
Creator: Aziz, K.; Hewett, T.A.; Arbabi, S. & Smith, M.
Partner: UNT Libraries Government Documents Department