K. Kapadia, Neil Rodrigues, Justin B. Hayes, Jade Juzswik, Yogesh Kapoor
{"title":"Optimization of Fortified Section Length in HIPPS System","authors":"K. Kapadia, Neil Rodrigues, Justin B. Hayes, Jade Juzswik, Yogesh Kapoor","doi":"10.2118/191616-MS","DOIUrl":null,"url":null,"abstract":"\n In the recent era of low commodity prices, the offshore oil & gas industry has focused on economic tie-backs rather than standalone projects to exploit potentially stranded reserves in the Gulf of Mexico. High pressure tie-backs to existing infrastructure may be lucrative, but they are often challenging with respect to pressure & safety ratings.\n A high integrity pressure protection system (HIPPS) can be used to safely contain pressures in a subsea flowline system when the shut-in tubing pressure (SITP) of a well exceeds the maximum allowable operating pressure (MAOP) of the tieback. As stated in API Standard 17O, a HIPPS system should be designed with highly responsive control systems, fast acting safety valves, and fortified sections of pipe known as \"burst free zones.\" The burst free zone is designed to have a higher MAOP than the rest of the flowline system. Optimizing the length of this zone can be achieved by accurately determining both the SITP and the time it takes for the system to reach the maximum SITP. These two key parameters are dictated by how the reservoir pressure responds during shut-in.\n With the availability of fast-transient multiphase flow simulation, it is possible to simulate the SITP and optimize the fortified section length. However, currently-available thermodynamic multiphase flow simulators do not provide an option to simulate near-wellbore reservoir phenomena. These software packages only simulate the shut-in of the well as an instantaneous pressure buildup, which is often very conservative for HIPPS and predicts fortified sections lengths that are longer than necessary.\n To simulate appropriate pressure buildup from the reservoir, a multiphase transient package is coupled with a reservoir simulation software that accounts for reservoir response and near-wellbore behavior. This model more accurately simulates the time required to reach the SITP, thus optimizing the selection of fortified section lengths. Additionally, reservoir and production factors that influence the fortified section length were also studied. One of the main influencing factors identified was fluid GOR. This is because a higher GOR fluid is more compressible; therefore, the time it takes to reach the maximum SITP increases, ultimately decreasing the required fortified section length. This paper will discuss how to apply known reservoir pressure responses to a coupled reservoir and multiphase transient simulator tieback scheme to optimize fortified section lengths when a HIPPS system is applied. It will also analyze the influence that production and reservoir characteristics have on the fortified section length and discuss how to optimize that length.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"143 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Day 3 Wed, September 26, 2018","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.2118/191616-MS","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
In the recent era of low commodity prices, the offshore oil & gas industry has focused on economic tie-backs rather than standalone projects to exploit potentially stranded reserves in the Gulf of Mexico. High pressure tie-backs to existing infrastructure may be lucrative, but they are often challenging with respect to pressure & safety ratings.
A high integrity pressure protection system (HIPPS) can be used to safely contain pressures in a subsea flowline system when the shut-in tubing pressure (SITP) of a well exceeds the maximum allowable operating pressure (MAOP) of the tieback. As stated in API Standard 17O, a HIPPS system should be designed with highly responsive control systems, fast acting safety valves, and fortified sections of pipe known as "burst free zones." The burst free zone is designed to have a higher MAOP than the rest of the flowline system. Optimizing the length of this zone can be achieved by accurately determining both the SITP and the time it takes for the system to reach the maximum SITP. These two key parameters are dictated by how the reservoir pressure responds during shut-in.
With the availability of fast-transient multiphase flow simulation, it is possible to simulate the SITP and optimize the fortified section length. However, currently-available thermodynamic multiphase flow simulators do not provide an option to simulate near-wellbore reservoir phenomena. These software packages only simulate the shut-in of the well as an instantaneous pressure buildup, which is often very conservative for HIPPS and predicts fortified sections lengths that are longer than necessary.
To simulate appropriate pressure buildup from the reservoir, a multiphase transient package is coupled with a reservoir simulation software that accounts for reservoir response and near-wellbore behavior. This model more accurately simulates the time required to reach the SITP, thus optimizing the selection of fortified section lengths. Additionally, reservoir and production factors that influence the fortified section length were also studied. One of the main influencing factors identified was fluid GOR. This is because a higher GOR fluid is more compressible; therefore, the time it takes to reach the maximum SITP increases, ultimately decreasing the required fortified section length. This paper will discuss how to apply known reservoir pressure responses to a coupled reservoir and multiphase transient simulator tieback scheme to optimize fortified section lengths when a HIPPS system is applied. It will also analyze the influence that production and reservoir characteristics have on the fortified section length and discuss how to optimize that length.