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SPE 35161 Pressure Transient Data Acquisition and Analysis Using Real Time Electromagnetic Telemetry L.E. Doublet,* Texas A&M U., J.W. Nevans,* Fina Oil & Chemical Company, M.K. Fisher,* ProTechnics Company, R.L. Heine,* Real Time Diagnostics, Inc., and T.A. Blasingame,* Texas A&M U. *SPE Members Copyright 1996, Society of Petroleum Engineers, Inc. Abstract This paper presents the operational procedures and the results for two pressure buildup tests performed using a wireless telemetry acquisition system (TAS) tool at the North Robertson (Clearfork) Unit (NRU) in Gaines, Co. Tx. Using a single pressure gauge system downhole we obtained real-time telemetry of pressure and temperature data at the surface, as well as a larger sampling of data that were stored in the downhole memory system. This new wireless telemetry acquisition system was developed to provide real-time pressure and temperature data at the surface by using an electromagnetic signal to transmit these data through the formation strata. The tool is fully programmable so that a wide range of sampling frequencies can be used. The system allows pressure and temperature data to be stored downhole (as in the case of a typical "memory" gauge), or these data can be transmitted to surface data acquisition systems. This provides real-time pressure and temperature data for pressure transient tests, stimulation monitoring. and long-term reservoir surveillance. Our objective is to demonstrate the use of this technology for pressure buildup tests in low permeability reservoirs. Our goal in utilizing this technology is to reduce the shut-in time requirements for pressure transient tests - which will ultimately result in a more cost-effective reservoir surveillance program as wells can be returned to production (or injection) as quickly as possible. Once the pressure data were acquired, we performed conventional semilog and log-log analysis, and we simulated test profiles to verify the analyses of the test data. Both surface and downhole pressure data were compared for consistency, and both types of data were analyzed in exactly the same fashion. The results of these analyses were essentially identical. This approach gave consistent estimates of reservoir pressure, permeability, skin factor, and fracture half-length for both of our case histories. Introduction The accurate acquisition and analysis of pressure transient data is an integral part of the reservoir surveillance process. By analyzing the characteristic shape of the pressure-time profile we can determine the reservoir-well model (i.e., homogeneous or dual-porosity reservoir conditions, hydraulically-fractured or horizontal well behavior, wellbore storage conditions, etc.). Specifically, we can use pressure transient data to estimate the following:–average reservoir pressure, –completion efficiency, –reservoir quality, –well drainage radius and reservoir shape, and –flow boundaries or other reservoir heterogeneities. Unfortunately, in the majority of operating environments the critical issue for most pressure transient tests is the timely return of a well to production or injection. This paper presents one methodology that shows promise in minimizing test time while fulfilling the data acquisition requirements. When performing pressure transient tests in the low permeability reservoirs of the Permian Basin (such as the NRU), it has been our experience that a test of at least two to three weeks is required for a comprehensive analysis to be possible. The issue is that the low permeability character of these reservoirs, combined with often severe wellbore storage effects, distorts test data and conventional analysis techniques cannot be used until these effects end. One remedy is a downhole shut-in device. but this device can be difficult to install, it requires considerable well preparation, and is quite expensive. Our approach was to minimize the test time by using real-time data for analysis. Conceptually, we can monitor the test and terminate once a valid analysis is obtained - but in our cases we continued data acquisition until the power source in the tool depleted. We did this for two reasons - first, we wanted to acquire as much data as possible; and second, we wanted to establish the practical operating limits of this data acquisition system. To estimate well drainage radius and identify flow boundaries we have found from pressure falloff tests that a total test duration of between five and eight weeks is required. Obviously, it is not economically feasible to shut-in producing wells for this period of time. In the future we may use the TAS tool for long-term surveillance tests, but at present this task is neither operationally nor economically feasible. P. 149
- Research Report > New Finding (0.67)
- Research Report > Experimental Study (0.66)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (24 more...)
An Integrated Geologic and Engineering Reservoir Characterization of the North Robertson (Clearfork) Unit: A Case Study, Part 1
Doublet, L.E. (Texas A&M U.) | Pande, P.K. (Fina Oil and Chemical Company) | Clark, M.B (Fina Oil and Chemical Company) | Nevans, J.W. (Fina Oil and Chemical Company) | Blasingame, T.A. (Texas A&M U.)
BRIEF SUMMARY Infill drilling of wells on a uniform spacing, without regard to reservoir performance and characterization, must become a process of the past. Such efforts do not optimize reservoir development as they fail to account for the complex nature of reservoir heterogeneities present in many low permeability carbonate reservoirs. These reservoirs are typically characterized by:–Large, discontinuous pay intervals –Vertical and lateral changes in reservoir properties –Low reservoir energy –High residual oil saturation –Low recovery efficiency The operational problems we encounter in these types of reservoirs include:–Poor or inadequate completions and stimulations –Early water breakthrough –Poor reservoir sweep efficiency in contacting oil throughout the reservoir as well as in the near-well regions –Channeling of injected fluids due to preferential fracturing caused by excessive injection rates –Limited data availability and poor data quality Infill drilling operations only need target areas of the reservoir which will be economically successful. If the most productive areas of a reservoir can be accurately identified by combining the results of geologic, petrophysical, reservoir performance, and pressure transient analyses, then this "integrated" approach can be used to optimize reservoir performance during secondary and tertiary recovery operations without resorting to "blanket" infill drilling methods. New and emerging technologies such as cross-borehole tomography, geostatistical modeling, and rigorous decline type curve analysis can be used to quantify reservoir quality and the degree of interwell communication. These results can be used to develop a 3-D simulation model for prediction of infill locations. In this work, we will demonstrate the application of reservoir surveillance techniques to identify additional reservoir pay zones, and to monitor pressure and preferential fluid movement in the reservoir. These techniques are: long-term production and injection data analysis, pressure transient analysis, and advanced open and cased hole well log analysis. The major contribution of this paper is our summary of cost effective reservoir characterization and management tools that will be helpful to both independent and major operators for the optimal development of heterogeneous, low permeability carbonate reservoirs such as the North Robertson (Clearfork) Unit. Introduction There are many complicated factors that will affect the successful implementation of infill drilling programs in heterogeneous, low permeability carbonate reservoirs such as the Clearfork/Glorieta of west Texas. Before we began this project, we conducted an extensive literature review to gain a better understanding of the producibility problems we face at the North Robertson Unit (NRU). Fortunately, these reservoirs have a long producing history and there is a large quantity of useful data available from case studies for primary, secondary, and tertiary operations in the Clearfork and other analogous reservoirs. In a 1974 case study concerning waterflooding operations at the Denver (San Andres) Unit, Ghauri, et al gave valuable insights concerning reservoir discontinuity, injector-producer conformance, and the effect of reservoir quality on reservoir sweep efficiency. Poor reservoir rock quality and the existence of discontinuous pay between injection and producing wells resulted in a recommendation to reduce nominal well spacing from 40 acres to 20 acres. An outcrop study on the San Andres was performed to verify reservoir discontinuity. Injection wells were completed and stimulated preferentially in an effort to flood only the continuous layers of the reservoir. The original peripheral injection design was converted to inverted nine-spot patterns in an effort to decrease the amount of water channeling and early water breakthrough via the most permeable members. P. 465
- Overview (1.00)
- Research Report > New Finding (0.67)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.68)
- Geology > Sedimentary Geology > Depositional Environment > Transitional Environment > Tidal Flat Environment (0.68)
- Geology > Mineral (0.67)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.93)
- Geophysics > Seismic Surveying > Seismic Modeling (0.67)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.45)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (27 more...)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- (4 more...)
- Information Technology > Modeling & Simulation (0.87)
- Information Technology > Data Science > Data Quality (0.34)