1. Background and Requirements

Drilling fluid, known as the "blood" of drilling construction, bears multiple tasks such as carrying drilling cuttings and balancing formation pressure during drilling. The rich "nutrients" in high-density drilling fluid make the "blood" viscous or high-temperature viscosity reducing, and the pumping pressure is high - very similar to the "three high" blood fluid. Using conventional ultra-high temperature and high density drilling fluid is like "three highs" patients working outdoors in scorching summer, with extremely high risks and difficulties. In addition, for every 100 meters increase in the depth of the formation, the temperature will increase by 2-3℃, and the formation pressure will also increase. Low drilling fluid density can cause accidents such as "blowout", while high density can cause leakage or damage to the formation. It can be said that without good "blood" - drilling fluid, oil exploration and development cannot proceed.

With the gradual advancement of oil and gas drilling targets towards deep formations, high-temperature and high-density drilling fluids with excellent performance are necessary conditions to ensure normal drilling construction. High density drilling fluid is prone to losing control of its rheological properties under high temperatures, affecting world-class problems such as drilling speed, pump pressure, displacement, and the degradation or failure of treatment agents. Regarding the research on ultra-high temperature and high-density drilling fluid technology, foreign countries focus on the development of high-performance specialized products, and the overall technology is relatively mature;The research on key treatment agents in China is mostly limited to the laboratory, with relatively few series of products formed, and the comprehensive performance of the system is also difficult to meet on-site needs.

Previously, most deep and ultra deep wells in China used key drilling fluid additives and technologies from abroad, which were very expensive. The "ultra high temperature and high density drilling fluid technology using low-priced barite weighting" successfully developed by Sinopec Petroleum Engineering Technology Research Institute has broken the monopoly position of foreign drilling companies in key technologies of high-temperature and high density drilling fluid, and significantly reduced drilling costs. Only the weighting agent can save about 40% of the cost compared to drilling fluids using weighting methods such as composite salts.

Lin Yongxue, a senior expert at Sinopec Group, proudly said “The ultra-high temperature and high-density drilling fluid technology developed this time has broken foreign technological monopolies and occupied the international forefront of technology, providing guarantees for Sinopec to build a 'one base, two wings, and three new' industrial pattern and build a world leading enterprise. It has made contributions to enhancing oil and gas exploration and development efforts, increasing speed, cost reduction, and efficiency.”

2. Breakthrough and Innovation

In order to solve the problems existing in high-temperature and high-density drilling fluid technology, the engineering institute adopted a combination of molecular simulation design and experimental methods to conduct research on the performance impact of drilling fluid systems under ultra-high temperature and high pressure conditions. Specific structures were introduced into the molecular structure to enhance the rigidity of the molecular chain, and the ultra-high temperature sealing and fluid loss agent SMPFL-UP was developed. The product molecules contain swelling micro regions, which improves the ability to resist mild sealing; Introducing special functional groups into the molecular structure ensures strong adsorption and hydration at high temperatures. An ultra-high temperature and high-density dispersant SMS-H has been developed, which allows the surface hydration film of the dispersed weighting agent particles to have a certain thickness at ultra-high temperatures, preventing the aggregation and sedimentation of the weighting agent particles, maintaining high-temperature stability, and improving the temperature resistance and viscosity reduction rate of the dispersant at high temperatures; Based on the two key treatment agents mentioned above, a high-temperature and high-density drilling fluid system was developed, using barite weighting. The drilling fluid with a density of 2.40 grams per cubic centimeter has good rheological properties and long-term high-temperature settlement stability at a high temperature of 220℃. Currently, over 90% of the high-temperature and high-pressure key exploration wells deployed in Sinopec have been successfully applied, with significant results.

The ultra-high temperature sealing and fluid loss agent SMPFL-UP adopts the "micro swelling sealing" mechanism for the first time, and the apparent viscosity and high-temperature and high-pressure filtration loss of the product's aqueous solution are lower than similar products at home and abroad; The viscosity reduction rate of ultra-high temperature and high density dispersant SMS-H is as high as 65%, which is superior to similar products at home and abroad. It has outstanding technical advantages when used in high-density drilling fluids.

We, DICO Energy Co., Ltd., have also developed and produced a series of fluid loss additives and dispersants, with performance and efficacy comparable to above SMPFL-UP and SMS-H. Please see below several products’ brief introductions. For specific information, you can search the product details page on our website www.dicoenergy.com:

High temperature Fluid loss Agent DOC-G86S is a kind of widespread use agent, has the characters of anti-salt,quick strength development and few free water. It is suitable for temperatures ranging from 0 to 230℃.

Multifunctional Fluid Loss Agent DOC-511Lcontains a large amount of -CONH2, -SO3H, -COOH and other highly adsorbable groups,for anti-salt, anti-temperature, adsorption of free water, loss of water plays an important role. Applicable temperature is 150℃ or below.

High Effective Cementing Dispersant DOC-F46S can adsorb on the surface of cement particles, reduce the consistency of cement slurry, improve the rheological properties of cement slurry, and is suitable for temperatures of 180℃ or below.

Dispersant DOC-F45L is a polycarboxylic acid dispersant product that can significantly reduce the consistency of cement slurry and improve the rheological properties of cement slurry. It is suitable for temperatures of 180 ℃ or below.

At present, the high-temperature and high-density drilling fluid developed by the Engineering Institute has been applied in 30 wells in the southwest, northwest, and northeast work areas of Sinopec, solving the prominent problems of controlling the flowability and suspension stability of high-density drilling fluid under high-temperature and high-pressure conditions. In the application, the drilling fluid has good performance, stable wellbore, and no settlement phenomenon has occurred, significantly reducing downhole complexity, improving drilling speed, saving drilling cycle and investment, The effect is significant. In 2010, it was successfully applied in the Guanshen 1 well, setting a record of "maximum drilling fluid density of 2.87 grams per cubic centimeter" both domestically and internationally, breaking the technical prohibition zone of authoritative foreign oil drilling fluid research institutions that "using barite as a weighting agent, the drilling fluid density cannot exceed 2.64 grams per cubic centimeter"; Set the record for the first deep well in Asia at the time at Shunbei Ying-1 well (8588 meters); Shunnanpeng 1 well won the competition with renowned foreign companies due to its excellent long-term high-temperature (bottom temperature of the completed well reaching 207.4 ℃) settlement stability performance. The completion acceptance was evaluated as "excellent" by Northwest Oilfield Company.

The ultra-high temperature and high-density drilling fluid technology has effectively ensured the exploration and discovery, increased storage and production, and low-cost and efficient development of Sinopec's deep formation oil fields, improved the technical level of drilling fluid for deep and ultra-deep wells in China, and will provide great guidance for the exploration of high difficulty ultra-deep formation oil and gas in the southwestern and southern regions of Shunbei, Shunnan, and other areas of Sinopec. It will also provide low prices for localization The popularization and promotion of high-quality drilling fluid products is of great significance!

3. Development and Prospects

According to reports, China's deep and ultra deep oil and gas reserves account for about 34% of the total resources, making them an important field for future oil and gas exploration and development. With the continuous deepening of oil and gas exploration and development in China, the application of ultra-high temperature and high-density drilling fluids will become the norm. The Engineering Institute will continue to deepen research, continue to carry out research in depth and breadth, increase research on the stability of ultra-high temperature settlement, the impact of high-pressure hot water on drilling fluid treatment agents and systems, and improve the technical level of Sinopec's ultra-high temperature and high-density drilling fluid, and provide technical support for efficient exploration and development of domestic oil and gas resources.