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Results
Abstract Nonuniform perforation properties and permeability variations close to the wellbore introduce heterogeneities which affect the injectivity decline in water injection wells. We present a method to calculate these effects and derive results for a simple model which incorporates the dependence of the water- quality-ratio on the entrance porewidths. Common degrees of heterogeneity may lead to significant changes in the injectivity decline, which cannot be described by conventional models of uniform wells. Early damage rates may be orders of magnitude larger than expected and wells with large initial skins are prone to having their half-lifes within this early region. Due to the resulting nonlinearities, extrapolations from test-injections may lead to wrong conclusions and it is usually not possible to predict the half-life by the conventional use of a single value for the water-quality-ratio. P. 631
- North America > United States > Texas (0.28)
- North America > United States > Louisiana (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.35)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
Abstract Since formation failure and sand production problems in water injection wells are less common than in producing wells, no general guidelines on how to complete water injection wells has appeared in the literature. However, formation failure related sand problems in water injection wells are serious enough that they should be taken into account during the selection of a completion method. This paper provides information on field-observed sand related problems encountered in water injection wells, and discusses the mechanisms leading to sand problems. It reviews the injectivity efficiency of several completion options, and provides guidelines for selecting completion methods for water injection wells drilled through formations prone to sand production. The paper emphasizes that even though sand problems in injection wells are less severe than in producing wells, careful selection and design of completion methods for injection wells can significantly reduce the likelihood and severity of future injectivity problems. P. 189
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Water Quality Requirements and Restoring Wells the Injectivity of Waste Water Disposal Abstract Water separated in desalters and other separation units in a gas-oil separation plant contained variable amounts of oil contaminant, suspended solids and chemicals. Two nearby wells are used to dispose the produced water from the plant. Due to the poor quality of the waste water and long shut-in period, one of the two wells encountered a significant drop in well injectivity. A thorough investigation was conducted to identify the damaging mechanism, design a treatment program to restore the well injectivity, and recommend guidelines for water quality needed to minimize formation damage. The study included characterization of the waste water, and conducting coreflood experiments to determine the effects of total suspended solids, oil content, particle size, H2S and iron content on the permeability of reservoir cores (sandstone formation). Finally, coreflood experiments were performed to determine an acid formulation which can be used to remove formation damage while maintaining the integrity of the formation (sandstone). Experimental results indicated that the waste water contained significant amounts of suspended solids (mainly iron sulfide) and oil (up to 250 mg/l). Coarse particles of more than 500 microns were present in the waste water. Coreflood results indicated that the waste water severely damaged reservoir cores. Formation of an external filter cake was the damaging mechanism observed in all coreflood experiments. Iron sulfide played an important role in the damage observed in the lab and field studies. The following water quality requirements were recommended to minimize loss of injectivity total suspended material (solids and oil) should not exceed 50 ppm, mean particle size should not exceed 4 microns, hydrogen sulfide concentration should not exceed 10 ppm, and total iron concentration should not exceed 2 ppm. Also, to prevent formation damage due to particle settling, it was recommended to continuously inject the waste water into the two disposal wells. Shutting in disposal wells for a long period of time will allow most of the particulate material to settle in the pore spaces, which will cause formation damage and loss of injectivity. To restore the injectivity of the damaged well, an acid formulation was designed which took into account formation mineralogy, presence of trapped oil, precipitation of iron, and elemental sulfur. The treatment was applied in the field where the acid was injected using a 1.5" coiled tubing. Ball sealers were added to the acid to ensure better diversion. The treatment was successful, and the well injectivity increased by more than 400%. P. 565
- North America > United States > Louisiana (0.28)
- Asia > Middle East > Saudi Arabia (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.74)
- Geology > Mineral > Sulfide > Iron Sulfide (0.54)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.85)
- Water & Waste Management > Water Management > Lifecycle > Treatment (0.76)
A STIMULATION TREATMENT AND EVALUATION OF A GRAVEL PACKED WELL; A CASE STUDY FROM THE STATFORD FIELD Abstract Several wells in the Statfjord field are restricted from producing at their maximum potential due to sand production. To optimize production different sand control techniques have been implemented. Gravel packed wells have contributed significantly to maintain production capacity. Typical production increase after gravel-packing has been 2 – 4000 Sm3/d. However, rapid plugging problems have been experienced after water breakthrough. Extensive scale dissolver and scale inhibitor treatments have been performed with varying success. Plugging problems experienced in the gravel packed wells are difficult to predict and overcome, In order to improve the productivity of the well and to establish a better understanding of the damage mechanisms, it was decided to perform a scale dissolver treatment and evaluate the stimulation effect by the use of a production logging tool (PLT). Well C-32, having a 55.5 m cased hole gravel packed interval was selected. The well was stimulated by a 2% KCl treatment prior to water breakthrough and treated by a scale dissolver and inhibitor shortly after water breakthrough. Production logging performed after installation of the gravel pack in November 1991 gave a basis for comparison, The evaluation of the data has shown that the plugging process is complex and difficult to interpret. We can conclude, however, that injection of fluids has improved the gravel pack productivity. The erosion potential has also been minimized due to reduced draw down across the gravel pack. The plugging mechanism is most likely a combination of scale and fines plugging the wire wrapped screens and the poorly filled perforation tunnels. The first stimulation operation had a payback time of 3 days and the second operation including production logging had a pay back time of 17 days. P. 313
- North America > United States (1.00)
- Europe > Norway > North Sea > Northern North Sea (0.85)
- Europe > United Kingdom > North Sea > Northern North Sea (0.70)
- Europe > Norway > North Sea > Tarbert Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > Statfjord Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 050 > Block 34/10 > Gullfaks Field > Statfjord Group (0.99)
- (11 more...)
- Well Completion > Sand Control > Gravel pack design & evaluation (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- (3 more...)