Meeting the Ultra HTHP Fluid Challenge

Abstract

Ultra high temperature, high pressure (uHTHP) conditions have a different definition depending on the region and the operator and Service Company. In this paper the definition used for uHTHP fluid performance is that of a fluid able to perform above 500°F and 30,000 psi. This paper describes the development of innovative drilling fluids specific to these well conditions. When bottomhole temperatures exceed 400°F, the design and engineering of drilling fluids can be challenging. Drilling fluids that destabilize can cause a variety of fluid control problems that could lead to drilling and completion issues. With Invert emulsion fluids, the major challenges encountered under these conditions are related to the thermal degradation of the emulsifier and wetting package that can lead to gelation and syneresis. Another challenge is fluid loss which is related to the emulsion stability and to the degradation of the fluid loss control additives. Finally, efficient control over the rheological properties – critical to the success of any well - can also be challenging, where effects from emulsion instability, filtration control degradation and rheology control additive degradation are coupled with increases in drilled solids, rapidly leading to rheological instability. This can manifest itself as high fluctuating rheologies and gelation, or loss of rheological properties that can give rise to sag of weight material, both potentially leading to associated well control problems. The paper describes the development of the new fluid system designed for such uHTHP environments, highlighting the chemical differences and compares the test data of the system with more conventional HTHP invert emulsion fluids. Data is presented showing the stability and performance of the new fluid over extended exposure to temperature >500°F, demonstrating tolerance to various contaminations and showing the rheological behavior and stability to 600°F and 40,000 psi.

Meeting Drilling Fluid Challenges in Gulf of Thailand Ultra-High Temperature Exploration Wells

“…Based on extensive laboratory testing during the fluid system development by the research and development group, it was determined that the combination of a nitrogen-free novel emulsifier (designed for thermal stability in excess of 550°F) and a modified naturally occurring polymer could be formulated to be stable up to more than 520°F (Stamatakis et al 2012). …”

Effect of Synthetic Quadripolymer on Rheological and Filtration Properties of Bentonite-Free Drilling Fluid at High Temperature

“…The sulfonic acid group of AMPS plays a role of hydration, and the side group -(CH 3 ) 2 CH 2 SO 3 Na can enhance the rigidity of the molecular chain, thus improving the thermal stability of the product. The rigid group of benzene ring contained in SSS monomer has a strong hindering effect [27,28]. Then, two double bonds in the molecule of DMDAAC contribute to form mesh structure.…”

Utilization of Nano and Micro Particles to Enhance Drilling Mud Rheology

“…HTHP drill holes are known as high temperature high pressure (HTHP) wells with bottom-hole temperatures ranging from (150-250 o C) and pressures from (689.48 to 1723.68 bar) [1]. The rheological parameters of drilling fluids are difficult to control at extreme temperatures and pressures [2], thus requiring the use of special formulations and systems.…”