Injection well

Natural gas cap drive may be supplemented by reinjection of produced gas, with the possible addition of make-up gas from an external source. The gas injection well would be located in the crest of the structure, injecting into the existing gas cap. 

The aquifer response (or impact of the water injection wells) may maintain the reservoir pressure close to the initial pressure, providing a long plateau period and slow decline of oil production. The producing GOR may remain approximately at the solution GOR if the reservoir pressure is maintained above the bubble point. The outstanding feature of the production profile is the large increase in water cut over the life of the field, which is usually the main reason for abandonment. Water cut may exceed 90% in the final part of the field life. As water cut increases, so oil production typically declines a constant gross liquids (oil plus water) production may be maintained. 

When a production or injection well is drilled, it is common practice to cement in place a casing which extends across the reservoir interval. The alternative is to leave the reservoir uncased, in a so-called bare foot completion, which is rarely done. When the drilling department finishes its work on the well, it is often left in the state of a cased hole, as on the left of Figure 9.14. 

Like steam injection, in-situ combustion is a thermal process designed to reduce oil viscosity and hence improve flow performance. Combustion of the lighter fractions of the oil in the reservoir is sustained by continuous air injection. Though there have been some economic successes claimed using this method, it has not been widely employed. Under the right conditions, combustion can be initiated spontaneously by injecting air into an oil reservoir. However a number of projects have also experienced explosions in surface compressors and injection wells. 

If there are significant amounts of both volatile and nonvolatile contaminants, remediation may be achieved by a combination of Hquid and vapor extraction of the former, and bioremediation of the latter. This combination has been termed "bioslurping", where the act of pumping out the Hquid contaminant phase draws in air at other wells to stimulate aerobic degradation (20). Such bioremediation requites that there be enough nutrients to allow microbial growth, and fertilizer nutrients are frequendy added at the air injection wells. Bioslurping has had a number of weU-documented successes. 

Injection Well Considerations. Eluid injection rate can have a significant effect on oil recovery economics. Elow is radial from the wellbore into the reservoir. Thus the region near the injection wellbore acts as a choke for the entire reservoir. 

The polymers exist in saline solution as tightly coiled chains and are readily adsorbed owing to relatively low solubiUty in hard water. Subsequent injection of soft, low salinity water uncoils the adsorbed polymer chains increasing water viscosity and reducing rock permeabiUty. This technology could also be used to reduce the permeabiUty of thief 2ones adjacent to injection wells. However, mechanical isolation of these 2ones may be necessary for cost-effective treatments. 

Gravity override of low density steam leads to poor volumetric sweep efficiency and low oil recovery in steam floods. Nonchemical methods of improving steam volumetric sweep efficiency include completing the injection well so steam is only injected in the lower part of the oil-bearing zone (181), alternating the injection of water and steam (182), and horizontal steam injection wells (183,184). Surfactants frequently are used as steam mobihty control agents to reduce gravity override (185). Field-proven surfactants include alpha-olefin sulfonates (AOS), alkyltoluene sulfonates, and neutralized... 

The oil 2one is fairly cool, and in a viscous oil reservoir this can result in Htde oil movement (Uquid blocking). Reverse combustion, in which oil ignition occurs near the production well, can avoid this problem. The combustion 2one moves countercurrent to the flow of air from the injection well. Oil flows through heated rock and remains mobile. Reverse combustion requires more air and consumes more oil than forward combustion. 

Examination of the records of wastewater injection wells that have been constructed in the United States shows that almost all the wells constructed thus far have been completed by one of three methods or close variations of them. The methods are ... 

Most wastewater injection wells will be constructed with injection... 

FIG. 25-78 Schematic diagram of an industrial-waste injection well completed in competent sandstone. (From Vreeman, H M, Standard Handbook of Hazardous Waste Treatment and Disposal, McGraw-Hill, 1988.)... 

In the primary binary loop, production wells recover 170°C hot water from the geothermal reservoir and deliver 3,036 m /lir at 14 bar to heat exchangers in the power plant. Water leaves the heat exchangers at 70-90°C and is recycled to the ground through a re-injection well at a depth of 400-600 m. In the secondary binary loop, the heat from the hot water evaporates the isobutane working fluid at 36 bar and 150°C (Table 4-2). 

Underground Injection Well Code (UlC) Identification Number... 

If yourfacility has a permit to inject a waste containing the toxic chemical into Class 1 deep wells, enter the 12-digit Underground Injection Well Code (UlC) identification number assigned by EPA or by the State under the authority of the Sate Drinking Water Act. If your facility does not hold such a p>ermit(s), enter not applicable, NA, in Section 3.1 la. You are only required to provide the UlC number for wells that receive the toxic chemical being reported. 

In Section 5, you must account forthe total aggregate releases of the toxic chemical to the environment from your facility for the calendar year. Releases to the environment include emissions to the air, discharges to surface waters, and on-site releases to land and underground injection wells. If you have no releases to a particular media (e.g., stack air), enter not applicable, NA do not leave any part of Section 5 blank. Check the box on the last line of this section if you use Part IV, the supplemental information sheet. 

Zero Releases. If you have no releases of a toxic chemical to a particular medium, report either NA, not applicable, or 0, as appropriate. Report NA only when there is no possibility a release could occur to a specific media or off-site location. If a release to a specific media or off-site location could occur, but either no release occurred orthe annual aggregate release was less than 0.5 pounds, report zero. However, if you report zero releases, a basis of estimate must be provided in column B. For example, if hydrochloric acid is Involved in the facility processing activities but the facility neutralizes the wastestreams to a pH of 6-9, then the facility reports a 0 release for the chemical. If the facility has no underground injection well, it enters NA for that item on the form. If the facility does not landfill the acidic waste, it enters NA for landfills... 

Releases to Underground Injection. Your facility performs no underground injection and therefore has no Underground Injection Well Code identification number. Not applicable, NA, should be entered in Part I, Section 3.11 and in column A.2 of Part III, Section 5.4. 

Maxiniizing the lvalue of the reservoir requires that full reservoir dynamics be considered in drilling wells and in extracting oil. Gas and water must be recycled through the strategic placement of injection wells wells with high gas-oil or water-oil ratios must be closed or not drilled and the rate of oil production must be controlled to maintain underground pressure. 

Exempt wastes are usually disposed of on location following permission from the state oil and gas division. Liquid wastes, if not evaporated or fixated on location, are usually injected into Class II injection wells—refer to Chapter 6, Environmental Considerations. Solid wastes, if not acceptable to local landfills, are remediated onsite or buried in some instances. Table 4-175 shows exempt and nonexempt waste [234]. 

Development Extension well QO (Step-out well) Development well Q (Production well) Service well 0 (Injection well, observation well, disposal well, etc.) Wells for production purposes - Production well 0 - Injection well 0 - Production- OO injection well - Appraisal well O - Piezometric well Special wells Disposal well O Absorptive well O Development well OOO Service well 0 Miscellaneous wells Appraisal well 00 (Extension well) Production well 0 (Exploitation well)... 

Classification by status Production well Dry well Production well Observation well Injection well Suspended well Abandoned well Gas-storage well Plugged and abandoned well Suspended well Gas producer Oil producer Injection well Exhausted producer... 

Development Development well OO Development well OO Exploration well O Auxiliary well O Production well O - oil - gas Injection well O - water - gas - in-situ combustion Appraisal well OO Development well O... 

Classification by status Abandoned well Suspended well Observation well Injection well Oil producer Gas producer Exhausted producer Production well Observation well Injection well Abandoned well Suspended well Geological research well - oil - gas Production well (active) - oil - gas Production well (inactive) Parametric well Injection well Abandoned well - dry - exhausted - technical reasons Well being drilled Abandoned well Suspended well Oil producing well Gas producing well Gas and oil producing well Injection well Well under observation Producing well depleted... 

Development Development well Q Development well 0 Service well 0 Development 0O0 well Service well 0 Development well - Development 0 test well - Development well0 - Injection well 0 - Observation well 0 Special well - Disposal well 0 - Storage well, etc. 0 Development well 0 Injection well 0... 

Figure 1. DC-biased, ten-well superlattice. A shaped laser field excites a wave packet localized initially in the injection well. The objective is to created the maximum density possible in the detection well, at a chosen target time.

The sum of all releases of the chemical to air, land, water, and underground injection wells. 

H2S production caused by the growth of sulfate-reducing bacteria in a biofilm in the reservoir rock close to the injection well (biofilm model)... 

Small-particle-size cement has found a number of uses in production and injection well casing repair jobs [440]. Oil-based cement is particularly useful for water shutoff jobs, because the hydrocarbon slurry sets only in the presence of water, so the oil-producing sections of a reservoir remain relatively damage free after water shutoff. The selective water shutoff with oil-based cement also has been used with polymers crosslinked by metal crosslinkers [442,1178]. 

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