Operators Optimize High-Pressure/High-Temperature and Ultrahigh-Pressure Perforation Strategies Using Laboratory Testing

Abstract

Multiple perforation laboratory programs have been conducted during recent years to support high-pressure/high-temperature (HP/HT) and ultrahigh-pressure (UHP) oil and gas field developments at various offshore locations globally. This paper highlights six such projects that supported activities within the Asia-Pacific, North Sea, and US Gulf of Mexico (GOM) (both Miocene and Lower Tertiary) regions. Each program was designed and conducted in collaboration with an operator and field operations personnel to help reduce potential risks, improve operational efficiency, and optimize well performance across a variety of challenging environments. Laboratory experiments were based on API RP 19B Sections 2 and 4, with test conditions customized to match specific downhole environments of interest (rock and fluid properties, stress, pressure, temperature, and flow scenarios). Matching downhole conditions at the laboratory proved important because this yields results that can be quite different from those obtained at surface (or scaled) test conditions. Reliable estimations of field perforation skin, sanding propensity, and the effectiveness of subsequent stimulation operations depend on realistic perforation and flow data obtained at relevant downhole conditions. The overriding goal for test design is to create and expose the laboratory perforation in an environment that matches its field counterpart as closely as possible. Beyond obtaining accurate flow data for skin and/or sanding propensity determination, post-test diagnostics, such as computed tomography (CT) and optical techniques, provide additional essential insight into the characteristics of the perforation tunnel, core interior, and the hole through the casing and cement. Results from these various programs were used to confirm or, in some cases, guide the field perforating strategy.