Standards Development

Scope

This document proposes the principles, design, and requirements for mechanical water-control completion of oil wells, including design principle, water-control completion design, procurement, operation requirements and evaluation, etc

Purpose

Horizontal wells are widely used due to their advantages such as larger oil reservoir contact area and higher recovery rate. However, during the production process, issues like heel-to-toe effect, unbalanced fluids influx, and early bottom water cone breakthrough often occur and lead to a significant increase in water cut, severely reducing the production efficiency of horizontal wells, increasing production costs, lowering carbon efficiency, and requiring more surface processing capacities and even significantly affecting the overall economics of oilfield development, making water control urgently needed.

Mechanical water control completion has become an indispensable measure for stable production. It has been widely used globally in regions such as the Middle East, the North Sea, Africa, America, Southeast Asia, and China, with a total application volume of over 3000 wells and continuously growing. With the continuous expansion of application scope and in-depth research, common, mature methods and understandings have been formed, and a standard drafting working group composed of outstanding technical experts from various countries, including China (Yanfeng Cao), Germany (Hou, Michael Zhengmeng), Indonesia (Marda Vidrianto), Russia (Aleksey Kazakov), Argentina (Sebastian Scalisi), the United Kingdom (Kerry Maclean), and Australia (Frank Xu Feng), has been established which possess the professional expertise to write ISO standards.

In terms of international standards, after querying, the only relevant standard for water control at present is API Spec 19 ICD-2020 "Inflow Control Devices", which mainly includes product requirements and guidelines for ICD and AICD, including functional specifications and technical specifications, product design, design verification and validation, material, document and data control, as well as quality requirements. It does not involve selection methods of different water control completion measures and design methods for different oilfield types and well conditions. Currently, mechanical water-control completion design is usually carried out by stead-state, multi-node simulation software (Netool), and dynamic reservoir simulation software if need, which has not yet established a mechanical water control completion design standard, hindering the efficiency and effectiveness of mechanical water-control completions.

CNOOC mechanical water-control completion design involving adapting and selecting ICD and AICD water control method is based on adaptability and regularity of water-control methods in different reservoir conditions, determined by stead-state and dynamic simulation of different types of watercontrol tools. Based on this, product performance requirements are provided to service providers, and the construction design and post-evaluation of mechanical water control completions are completed. CNOOC mechanical water control completion technology has been developed through scientific research for more than ten years since 2008, and has been continuously applied on more than 200 well. The water control measures covering the main water control completion tools and technologies used domestically and internationally, and a complete set of completion water control technology system has been formed. At the same time, the effective rate of measures has significantly increased from an average of 77% before 2020 to 93% in 2023, with remarkable implementation effects becoming an essential measure for stable production and increasing production in oilfield development. In addition, in 2023, China Offshore Oil drafted enterprise standard "Oil and Gas Well Water Control Completion Design Guidelines", which proposes principles for oil and gas well water control, water analysis and control strategies, design content and process, process requirements (drilling, completion, perforation, sand prevention stages), scheme design, performance evaluation, etc.

In conclusion, the oilfield development worldwide has a strong demand for water control, and mechanical water control completion has become a major measure. The design of mechanical water control completion is strongly related to the effectiveness of oilfield development and directly impacting the production of oil wells. Therefore, it is necessary to establish standards to better guide water control design and operations for offshore oil wells, significantly improve the long-term water control effectiveness, and fill the gap of standardisation in the water control field.