Standards Development

Scope

This document specifies the requirements for the design, technical specifications, testing and inspection, packaging, storage, and transportation of downhole throttles for gas well hydrate mitigation.

Purpose

Natural gas is a vital clean energy source that supports the normal operation of the global economy and daily life. It is abundant in reserves and accounts for more than 23% of global primary energy consumption. Currently, there are over 2.5 million gas wells worldwide, most of which rely on surface choking for pressure reduction during production. However, this approach often leads to hydrate formation in surface pipelines. Hydrate blockages can significantly reduce well productivity or even lead to shutdowns, while also posing safety risks due to equipment overpressure. Therefore, effective hydrate prevention is essential for the efficient development of natural gas resources. Downhole choking technology is a cost-effective and environmentally friendly method for hydrate prevention. At its core is the downhole choke tool, which is installed in the production tubing to reduce gas pressure within the wellbore. The geothermal heat in the well is then utilized to inhibit hydrate formation. This technology can significantly reduce the cost of hydrate management while promoting energy conservation and emission reduction.

Since the 1980s, downhole choking technology has been widely applied in hydrate prevention for gas wells. After decades of development, a series of downhole choke tools has been established to suit various tubing sizes (2", 2", 3½", 4½"), including both fixed and adjustable types, with three levels of 35 MPa, 70 MPa, and 105 MPa. These tools are suitable for complex well environments containing condensate and hydrogen sulfide.

To date, downhole throttles have been successfully applied in more than 10,000 wells worldwide, across Asia, North America, and Europe. International applications include 310 installations in Aktobe, Kazakhstan, at depths ranging from 700m to 2,500m. Since 2013, new production wells in Canada’s Tupper Field have routinely adopted downhole throttling technology. The technology has also been applied in fields such as Placid Montney (Canada) and Santo Stefano Mare (Italy, Adriatic Sea). downhole throttles are extensively utilized in China's oil and gas fields such as TotalEnergies and Shell in China, downhole throttles have been deployed in more than 90% of wells. These practices highlight the importance of internationally recognized tool quality and inspection standards for promoting technical mutual recognition and cooperation. Across China-particularly in the Sichuan–Chongqing gas provinces and the Changqing and Jianghan fields-downhole throttling is widely adopted for hydrate control, with maximum operating differential pressures of up to 62MPa and hydrogen sulfide concentrations as high as 94.3g/m³. It has become the principal technology for gas well hydrate mitigation in China. Together with the international deployments above, Chinese installed base evidence mature manufacturing and testing capabilities, supported by international expertise and market demand, thereby laying a solid foundation for an international standard.

In the absence of an internationally recognized standard for downhole throttles, a number of issues have emerged between users and manufacturers/service providers during field application and international technical cooperation. These include the absence of a unified classification and naming system for the tools, resulting in differing understandings between parties, causing technical policies to fail to meet well conditions and making technical sharing and mutual recognition impossible; the lack of internationally accepted quality and inspection standards for the tools, which hinders the alignment of technical trade needs among stakeholders and provides no authoritative basis for resolving quality disputes; the existence of these issues has adversely affected technological progress and international technical trade cooperation. Therefore, it is essential to develop an international standard to establish technical consensus, support global trade, promote tool innovation, and contribute to global energy efficiency and emission reduction efforts.