The recent period of depressed oil prices which reached as low as $US 5.97/bbl for heavy oil drove major reviews in heavy oil recovery economics, and led to a substantial shift in the operation of four (4) of Petrotrin's thermal projects. The shift was predicated upon key factors such as:experience derived from the North Fyzabad project, a mature steamflood which was converted to a heat scavenging project in 1996the need to assure project viability by maintaining a reasonable lifting cost.at least sustain the present level of decline rates associated with each project. In February 1999, North Palo Seco, Apex Quarry and Bennett Village, three (3) mature thermal projects at Petrotrin were placed on the water-alternating-steam-process (WASP) and another, Central Los Bajos was converted in August 1999. The four (4) projects are in close proximity each exploiting the Lower Morne L'enfer sandstone and their operating and reservoir characteristics are quite similar. In two (2) of the schemes, selected patterns were converted to WASP, the other patterns being kept on continuous steam. The criteria for pattern selection were pattern temperature, steam-oil-ratio, produced WOR, susceptibility to steam breakouts, and minimal alteration to main piping system. The paper discusses capital expenditure for the conversion which was kept to an absolute minimum, operating cost which was subsequently reduced; profitability which increased; reservoir response to water injection which resulted in an increase in oil production rate and problems associated with implementation. The paper also discusses techniques of day-to-day flood monitoring, highlights operational problems and presents future operating strategies.
Based on the success of the Cruse ‘E’ Pilot steamflood, Petrotrin decided to venture into a large-scale thermal project called the Cruse ‘E’ (IADB) Expansion Steamflood. The project area consists of 270 acres in the zone of interest, the Upper Cruse ‘E’ sand. Surface and infrastructure work began in January 1994, and was followed by rig work - drilling, recompletions, and workovers. Sixty (60) new wells comprising twenty-eight (28) injectors and thirty-two (32) offtakes were drilled and completed to form twenty-eight (28) patterns. Also thirty-five (35) existing wells were utilized as offtakes. The project was commissioned in January 1996 when steam injection began. It was predicted in 1992 by reservoir simulation that 11 million barrels of heavy oil would be recovered over fifteen (15) years with production peaking in the year 2000. However, in 1998 when oil production reached 900 bopd, the project was adversely affected by environmental concerns to a residential area in the vicinity of the steamflood and it was actually shutdown by order of the Environmental Management Agency in November 1998. Extensive environmental work was undertaken by Petrotrin in the areas of communication, training and operations to improve the safety and environmental aspects of the steamflood, and ensure that it was brought up to required environmental standards. After forty (40) months of inactivity, approval was finally obtained in March 2002 from the environmental regulatory agency to restart steam injection. This paper discusses the performance of the steamflood during steam injection and during no injection, the operational and economic aspects of the project, and the environmental upgrade conducted. The paper also discusses the production response since restart, the amended forecast from history-matched reservoir simulation and future operating strategies. Introduction The Cruse ‘E’ (IADB) steamflood is situated in the southwestern part of Trinidad in the Parrylands area, about 8 miles from the town of Point Fortin [Fig. 1]. It is one of several active thermal projects being operated by Petrotrin, and is the most recent steamflood developed by the company. Some of the very mature steamfloods have been converted to heat scavenging projects. Oil production from these thermal projects and heat scavenging schemes account for eighty percent [80%] of EOR production. The Cruse ‘E’ Expansion Steamflood was undertaken following the success of the Cruse ‘E’ Pilot Project. With loan financing from the Inter-American Development Bank, twenty-eight [28] new patterns were formed by drilling sixty [60] wells and incorporating thirty-five [35] existing wells in the thermal area [Fig. 2]. Steam generation and distribution equipment and production facilities were installed during 1995 and actual steam injection began in January 1996. The shallow Cruse ‘E’ sands were ideal for steamflooding, and as a result response was obtained in just nine (9) months. Twenty-two (22) months later production reached 1200 bopd. For environmental reasons, the flood was shut down in November 1998 and approval was not obtained to re-start until March 2002. The factors that will contribute to the success of this project are:high reserves of shallow heavy oil of average 17° API.reliable, adequate supplies of fresh water for injection and natural gas for steam generation.good reservoir continuity with the project limits.the accumulated expertise gathered in the past thirty [30] years in enhanced oil recovery from Petrotrin's predecessor companies.the success of the Pilot Project.
Based on the success of the Cruse ‘E’ Pilot steamflood, Petrotrin decided to venture into a large-scale project of a similar nature called the Cruse ‘E’ (IADB) Expansion Steamflood. The project area consisted of 270 acres, with an estimated original oil in place of 31.1 million barrels in the zone of interest, the Upper Cruse ‘E’ sand. Surface and infrastructure work began in January 1994, which was followed by rig work - drilling, recompletions, and workovers. Sixty (60) new wells comprising twnty-eight (28) injectors and thirty-two (32) offtakes were drilled and completed to form twenty-eight (28) patterns. Also thirty-five (35) existing wells were utilized as offtakes. The project was commissioned in January 1996 when steam injection began. This brought the number of active steamfloods and WASP projects at Petrotrin to eight (8). It was predicted by reservoir simulation that 11 million barrels of heavy oil would be recovered over fifteen (15) years with production peaking in the year 2000. However, in 1998 when oil production reached 877 bopd, the project was adversely affected by environmental concerns to a residential area in the vicinity of the steamflood and it was actually shutdown by order of the regulatory body in November 1998. Extensive environmental work was undertaken in the areas of communication, training and operations to improve the safety and environmental aspects of the steamflood, and ensure that it was brought up to the environmental standards required. After forty (40) months of inactivity, approval was finally obtained in March 2002 from the regulatory body to restart steam injection. This paper discusses the performance of the steamflood during steam injection and during no injection, the technical, operational and economic aspects of the project, and the environmental upgrade conducted.. The paper also discusses the restarting exercise conducted for steam injection and presents future operating strategies. Introduction The Cruse ‘E’ (IADB) steamflood is situated in the southwestern part of Trinidad in the Parrylands area, about 8 miles from the town of Point Fortin [Fig. 1]. It is one of several on-going thermal projects being operated by Petrotrin, and is the most recent steamflood developed by the company. Some of the very mature steamfloods have been converted to heat scavenging projects. Oil production from these thermal projects and heat scavenging schemes account for fifty percent [50%] of EOR production. The Cruse ‘E’ Expansion Steamflood was undertaken following the success of the Cruse ‘E’ Pilot Project. With the help of financing from the Inter-American Development Bank, twenty-eight [28] new patterns were formed by drilling sixty [60] wells and incorporating thirty-five [35] existing wells in the thermal area [Fig. 2]. Steam generation and distribution equipment and production facilities were installed during 1995 and actual steam injection began in January 1996. The shallow Cruse ‘E’ sands were ideal for steamflooding, and as a result response was obtained in just three (3) months, and twenty-two (22) months later reached 1200 bopd. For environmental reasons, the flood was shut down in November 1998 and approval was not obtained to re-start until March 2002. The factors that will contribute to the success of this project are:high reserves of shallow heavy oil of average 17° API.reliable, adequate supplies of fresh water for injection and natural gas for steam generation.
Summary The Cruse ‘E’ steamflood was designed and developed by Petrotrin from 1994 to 1996. This paper discusses the performance of the steamflood during steam injection and during a 4-year period of noninjection. It also covers the operational and economic aspects of the project and discusses the production response since restart, the amended forecast from history-matched reservoir simulation, and future operating strategies.
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