A Method To Convert Multiple-Shot Section Openhole Completions Into Cased-Hole Completions With Zonal Isolation
Abstract: A method to convert multiple shot section open hole completions into cased hole completions has been developed and tested. This method provides zonal isolation between shot sections thus helping prevent injection fluid loss to non-pay intervals. The process, called "Puddle-Pack", involves formulating a permeable resin fill material and placing the material in the shot open hole to fill the large voids. The excess material is then drilled out and underreamed to allow a liner to be run and cemented in place. Thi… Show more
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Cited by 5 publications
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Tracer Surveys To Identify Channels for Remedial Work Prior to CO2 Injection at MCA Unit, New Mexico
A tracer program to identify channels within the Grayburg/San Andres formations prior to CO2 injection has been performed and analyzed at the Maljamar Cooperative Agreement (MCA) Unit. For safety and costs reasons two separate interwell tracer surveys or phases were conducted. In the Phase 1 tests tritium was injected into 62 wells through injection headers to identify field areas where channelling occurs. Within 12 weeks, 25 out of 177 producing wells sampled had a response. Tritium was used because it has a larger acceptable response window between its minimum detectable level and the maximum safe peak response than other available radioactive tracers. This first survey provided important design information for the second survey which included tracers with smaller response windows. The Phase 2 tests included the 19 producers with the larger Phase 1 responses and their 27 active offset injectors. With the use of multiple tracers, the Phase 2 tests identified 14 problem injection wells as channelling sources. Unexpectedly, the source of some channels was farther away than the nearest offset injectors. In addition, the two tracer surveys showed that tracer flow is sensitive to changes in operating conditions. Thus, every reasonable effort should be made to perform tracer surveys under normal operating conditions. Introduction Since EOR injection fluids such as CO2 are expensive, every reasonable effort should be taken to increase their efficiency. Flow channels between injection and production wells can cause inefficient use of injected fluids. Such channels need to be identified early to allow remedial work ore injection wells before the EOR project begins. Well-to-well tracers are an effective way to identify such flow channels and their field wide directional trends. For safety and costs reasons, two separate tracer surveys were conducted at the Maljamar Cooperative (MCA) Unit prior to a proposed CO2 trod of the Grayburg/San Andres formations. In the first survey, tritium was injected into all active injection wells within the proposed CO2 Project Area to identify areas with channeling With tritium, a large area can be surveyed at a relatively low cost. The second survey required the use of three tracers (tritium, carbon-14, and iodine-125) to identify the source injection wells within each early responding area. Besides identifying the channelling areas, the first survey provided important design information for the second survey. Tritium is a relatively safe tracer that has a much higher allowable peak response under Nuclear Regulatory Commission (NRC) guidelines than other alternative radioactive tracers. in addition, tritium is relatively easy and inexpensive to detect. By knowing the amount of tritium causing a given response at a producing well, the required amount of carbon-I 4 or iodine-125 in the second survey could be more reliably estimated. Then, the more stringent NRC response ceilings for carbon-I 4 and iodine-125 could be safely met. At the same time, the designed response had to exceed the detection threshold of available counting instruments. The window between the minimum detectable level and the maximum safe peak response is much wider for tritium. The first survey took advantage of this larger window. MCA UNIT BACKGROUND The 8,040 acre [32 × 106 m2] MCA Unit occupies a large part of the Maljamar Field in western Lea County, New Mexico (Figure 1). The Grayburg-San Andres pool was discovered in 1926, followed by the majority of development drilling in the early 1940s. P. 567^
Tracer Surveys To Identify Channels for Remedial Work Prior to CO2 Injection at MCA Unit, New Mexico
A tracer program to identify channels within the Grayburg/San Andres formations prior to CO2 injection has been performed and analyzed at the Maljamar Cooperative Agreement (MCA) Unit. For safety and costs reasons two separate interwell tracer surveys or phases were conducted. In the Phase 1 tests tritium was injected into 62 wells through injection headers to identify field areas where channelling occurs. Within 12 weeks, 25 out of 177 producing wells sampled had a response. Tritium was used because it has a larger acceptable response window between its minimum detectable level and the maximum safe peak response than other available radioactive tracers. This first survey provided important design information for the second survey which included tracers with smaller response windows. The Phase 2 tests included the 19 producers with the larger Phase 1 responses and their 27 active offset injectors. With the use of multiple tracers, the Phase 2 tests identified 14 problem injection wells as channelling sources. Unexpectedly, the source of some channels was farther away than the nearest offset injectors. In addition, the two tracer surveys showed that tracer flow is sensitive to changes in operating conditions. Thus, every reasonable effort should be made to perform tracer surveys under normal operating conditions. Introduction Since EOR injection fluids such as CO2 are expensive, every reasonable effort should be taken to increase their efficiency. Flow channels between injection and production wells can cause inefficient use of injected fluids. Such channels need to be identified early to allow remedial work ore injection wells before the EOR project begins. Well-to-well tracers are an effective way to identify such flow channels and their field wide directional trends. For safety and costs reasons, two separate tracer surveys were conducted at the Maljamar Cooperative (MCA) Unit prior to a proposed CO2 trod of the Grayburg/San Andres formations. In the first survey, tritium was injected into all active injection wells within the proposed CO2 Project Area to identify areas with channeling With tritium, a large area can be surveyed at a relatively low cost. The second survey required the use of three tracers (tritium, carbon-14, and iodine-125) to identify the source injection wells within each early responding area. Besides identifying the channelling areas, the first survey provided important design information for the second survey. Tritium is a relatively safe tracer that has a much higher allowable peak response under Nuclear Regulatory Commission (NRC) guidelines than other alternative radioactive tracers. in addition, tritium is relatively easy and inexpensive to detect. By knowing the amount of tritium causing a given response at a producing well, the required amount of carbon-I 4 or iodine-125 in the second survey could be more reliably estimated. Then, the more stringent NRC response ceilings for carbon-I 4 and iodine-125 could be safely met. At the same time, the designed response had to exceed the detection threshold of available counting instruments. The window between the minimum detectable level and the maximum safe peak response is much wider for tritium. The first survey took advantage of this larger window. MCA UNIT BACKGROUND The 8,040 acre [32 × 106 m2] MCA Unit occupies a large part of the Maljamar Field in western Lea County, New Mexico (Figure 1). The Grayburg-San Andres pool was discovered in 1926, followed by the majority of development drilling in the early 1940s. P. 567^
Standalone Screen Design and Evaluation for Cased and Perforated Application in Unconsolidated Formations: The Role of Perforation Strategy and Sand Control Design on Well Productivity
Productivity of cased and perforated wellbores completed with standalone screen depends on the interactions of parameters such as perforation diameter, length, phasing and density, the gap between the casing and the standalone screen, and standalone screen aperture/pore size. Moreover, the permeability of the sand in the gap plays a major role in the overall productivity. This study aims at providing a numerical estimation of pressure drop for such completions. This study uses Computational Fluid Dynamics (CFD) in order to simulate the flow around a wellbore equipped with cased and perforated completion with standalone screen. Slotted liner was used as the standalone screen in this study. Details of such a complex completion were imported into the Finite Volume (FV) based numerical simulation via Computer-Aided Design (CAD). In addition to the geometrical design of the completion, different scenarios for the perforation stability, which affect the permeability of the perforation tunnel and result in potential fill-up of the annular gap between the slotted liner and perforations, were investigated. A large number of simulations (over 200 models) were completed to cover the different scenarios for perforation design and strategy along with different Open to Flow Area (OFA) values for the standalone slotted liner. Based on the results, completion efficiency is strongly changed by perforation and gap flow properties. The OFA for the standalone slotted liner completion has minor influence on the overall pressure drop if the gap between the casing and the standalone screen and the perforation is clean, unless the perforations are collapsed and the annular gap between the casing and slotted liner is filled up with sand. This is mainly because perforation parameters, such as penetration and diameter dominate the effect of all the other parameters, including slotted liner configuration. The results emphasize the effect of the completion geometry, perforation strategy, and opening size on the skin and productivity. Another main observation was the need to better understand the stability of the perforations and sanding potential from perforations, which dictate the permeability of the perforation and annular space. The results of this study highlight the comparative importance of different standalone screen designs and perforation parameters on well productivity. This study is the basis for optimizing the sand control and perforation strategy as an alternative to other completion types such as gravel packing in cased and perforated completions in vertical and slant wells.
SPE Members Abstract A major obstacle to the successful implementation of an enhanced oil recovery project is the proper completion of the injection wells to prevent fluid loss. The injectants are often expensive and highly corrosive. Further, economics dictate in many cases that the wells to be completed and used as the input wells for the injectant be existing wells; the economics simply do not allow for the drilling of new injection wells. These wells were originally designed without this purpose in mind and are very often old, at least thirty years. Most of these wells suffer from poor casing integrity and small casing sizes. Again, economics do not allow for the use of corrosion resistant high nickel chrome alloy liners. To solve these problems, a unique completion method was designed using fiberglass casing and a drillable permanent packer as the liner hanger. The permanent packer was also used as the injection packer. This system allows the use of corrosion resistant fiberglass for control of the corrosive injection fluids and imparts the ability to drill out the permanent packer and the fiberglass liner to prevent the loss of the well bore in the future, if mechanical problems do arise. problems do arise. This paper will describe in detail the development of the injection system, and the remedial procedures required. Case histories from an procedures required. Case histories from an operator in southeastern New Mexico will demonstrate the successful recompletion of existing well bores into injection wells, supported by injection profite data that demonstrates injected fluid control. Economics demonstrating cost effectiveness of the unique completion design are also presented. Introduction The slimline fiberglass liner system was developed to allow an operator to successfully and economically implement a tertiary CO2 miscible flood. A pilot CO2 injection project had demonstrated the potential revenue to be realized by tertiary oil recovery. There were, however, major economic and operational concerns to be addressed before a field-wide CO2 injection program could be undertaken. The existing injection wells were all over 30 years old. Originally drilled as producing wells, these wells had been converted to water injection wells during the implementation of a field-wide water flood program in the early 1960's. These injection wells all had two common problems; poor casing integrity and small casing sizes. Injection profiles indicated a significant amount of injected water-as much as 90% in some cases-was lost to non-pay intervals and the majority of the injection wells had four and one half inch (4 1/2") casing, with the balance having five and one half inch (5 1/2") casing. Since the loss of only a small amount of CO2 into a non-pay interval could significantly reduce the profitability of the project, the injection wells profitability of the project, the injection wells would have to be repaired. If the wells could not be repaired, replacement injection wells would have to be drilled and the old wells plugged and abandoned. The estimated 14 million dollars this would require, would severely effect the economics of the project. The CO2 pilot project had also shown the injectant to be extremely corrosive. Standard carbon steel liners would not, in all probability, survive the life of the CO2 injection flood. Corrosion of the liners would lead to the loss of CO2 into non-pay intervals. In addition, the small casing sizes were a handicap. If a carbon steel alloy liner was run and corrosion caused a loss of casing integrity, it would mean the loss of the well bore. There was not enough room to run another liner, and it was not economically feasible to attempt fishing and milling operations to recover the steel liner and recomplete the well. P. 321
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