Abstract

Early phases of development for projects with hydrate mitigation strategies incorporating low dose hydrate inhibitors (LDHIs) are often subjected to assumptions in LDHI dosing requirements, which impact both CAPEX (tanks, pumps, umbilicals) and OPEX (chemical spend). These assumptions can influence the viability of projects moving forward, especially in low-cost environments, and has reemphasized the need for a critical evaluation of the state of the industry for LDHI performance under a variety of conditions. Within this paper, a series of tests examining the impact of produced water salinity and water cut on LDHI effectiveness using a range of hydrocarbon fluids was carried out using high pressure rocking cells. Standard test conditions were utilized throughout the investigation in constant mass rocking cells with an initial pressure of 2,500 psi using synthetic Green Canyon gas. Salinity sensitivity studies maintained held water cuts constant at 40 vol% while varying the salinity from condensed water up to 250,000 TDS NaCl. Water cut sensitivity studies examined both, 35,000 TDS (seawater) and 125,000 TDS, brine conditions while the water cut was varied from 5% to 80%. Salinity sensitivities were repeated using two commercially available anti-agglomerates (AAs) as standards and three hydrocarbon phases, including two different black oils and kerosene. Water cut sensitivities were conducted with one commercially available AA and two hydrocarbon phases: a black oil and kerosene. The significance of these matrices demonstrates that project planning should include baseline testing with fluids representing actual expected field conditions to better assess AA requirements for new developments. In many cases, project assumptions about costs or chemical performance should be reexamined.

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