This paper presents an overview of BP's approach to Hydrate Management on new Gulf of Mexico (GoM) Deepwater Developments and Operations using the first and second generation (low and high water cut) Anti Agglomerate Low Dosage Hydrate Inhibitors (AA LDHIs). It also describes how these AA LDHIs are used in conjunction with more conventional hydrate management approaches to reach an optimal cost effective field hydrate management solution.
The paper also outlines how the challenges outlined by BP and other major oil producers to the oilfield chemical suppliers at various subsea conferences were taken seriously, and how suppliers have risen to these challenges both in terms of cost, chemical technology development and product delivery to the field.
Logistics, HSE, chemical injection and life of well operating envelope challenges need careful consideration at all stages of hydrate management and the paper outlines an integrated approach to cover these on a life of asset development. The impact of AA LDHIs and methanol on downstream transportation and refining facilities are also described as well as impacts on crude marketability and crude quality banks.
The paper will touch on all these aspects and outline new challenges that are being faced as we move towards High Pressure High Temperature (HPHT) Developments with record water depths and drilling depth challenges.
BP has historically managed hydrate challenges in their GoM operations using methanol, glycol, gas dehydration, insulation and line depressurization to ensure safe operations and in doing so has made sure there is at least one secondary method for hydrate mitigation. However, the demand on these existing techniques has stretched their capabilities and new innovative methods have become necessary as we have moved from relatively shallow water of 500 feet through 3,000 feet and then on to newer depth horizons and challenges in 6,000+ feet water depth.
These new depths, longer flowline tie backs, longer riser lengths, and installation challenges on hardware and equipment have put an appreciable focus on new materials, novel pipe in pipe and heated systems1 as well as challenged traditional chemical hydrate management methods such as methanol. In light of this, BP, a few other major operators and several oilfield service companies started to explore the possibility of alternate hydrate inhibitors to methanol which would function in a different way to traditional thermodynamic hydrate inhibitors. The first major full scale production and application of these was on the ETAP development in the North Sea2 and these materials are being used there even today.
BP initially focused on kinetic hydrate inhibitors (KHI's) for the North Sea region as the typical levels of hydrate subcooling are in the region of 10 to 17°F range which are within the 23°F maximum limit for most KHI's. In addition KHI's functionality is time dependent and most only offered limited duration of hydrate inhibition. These limitations of KHI's remain even yet, but the chemical suppliers are re-focusing efforts on developing new KHI products that may unlock the subcooling barrier and enhance the length of time these chemicals function.