Recently, the Shiqian 5 well located in the Zhundong New Area of Tuha Oilfield applied deep and ultra deep fracturing technology and a low-cost, low damage ultra-high temperature fracturing fluid system. After production, the daily gas production reached 14500 cubic meters, with a maximum daily gas production of 220000 cubic meters, breaking the single well production record of deep tight sandstone gas reservoirs in Tuha Oilfield.

The "highway" for the expansion of deep tight gas reservoirs in Tuha Oilfield has achieved a 100% success rate in reservoir fracturing construction at depths of over 5000 meters

In recent years, the exploration and development of Tuha Oilfield has entered the unconventional, deep and ultra deep fields. The reservoir has a depth of 4000 to 7000 meters and exhibits characteristics of density, low porosity, and low permeability. Artificial fractures must be generated through hydraulic fracturing in order for oil and gas wells to have production. At the same time, deep and ultra deep fracturing is accompanied by harsh conditions such as ultra-high temperature, ultra-high pressure, and high stress, which pose greater challenges to fracturing technology and urgently require the development of deep and ultra deep fracturing technology.

The technical personnel of Tuha Oilfield have started from the aspects of fracturing tubing, fracturing fluid system, and key fracturing parameters, relying on scientific research projects to carry out reservoir property evaluation, rock mechanics analysis, predict formation fracture pressure, and jointly research with China Petroleum Exploration and Development Research Institute and Engineering Technology Research Institute to select high pressure resistant and large-diameter fracturing tubing, ensuring the safety of the wellbore and the demand for high displacement construction.

The previous fracturing fluid had a temperature resistance range of 80 to 90 degrees Celsius. The current deep temperature is 150 degrees Celsius, which can cause a decrease in viscosity and degradation of the fracturing fluid, poor sand carrying capacity, and lead to sand blockage during construction. Technicians have developed a low friction and low damage fracturing fluid system with a temperature resistance range exceeding 150 degrees Celsius through technological breakthroughs, solving the contradiction between the "reservoir temperature resistance" and "wellbore friction" of fracturing fluids. Among them, the function of delayed crosslinking has the greatest potential for application, which can achieve a delay of 2 to 5 minutes, allowing the fracturing fluid to maintain low viscosity in the wellbore and reduce friction, while maintaining high viscosity in the reservoir and carrying proppants that support fractures. Meanwhile, through on-site testing and further optimization, the concentration of fracturing fluid additives has reached the optimal ratio, meeting the requirements of low cost and low damage.

Integrated innovative deep and ultra deep fracturing supporting technology. In response to the problems of tight reservoirs, high fracture pressure, and difficulty in creating fractures, Tuha Oilfield has carried out the integrated application of "small particle size sand plug grinding+low concentration sand plug prediction+combined particle size proppant support+real-time pump injection adjustment" technology. The fracturing transformation depth exceeds 6000 meters, the construction pressure can reach up to 128 megapascals, and the construction displacement can reach up to 14 cubic meters per minute, achieving the transformation of deep and ultra deep reservoirs from "pressed" to "well pressed".

Form a template for deep and ultra deep fracturing technology. Based on the characteristics of the reservoir, Tuha Oilfield has determined the transformation mode of "high displacement, high viscosity, and long fractures throughout the entire process, low sand ratio combined particle size proppants, and real-time pressure control to ensure wellbore safety", expanding the "small hole throat" of deep tight sandstone into a "highway".

The deep and ultra deep fracturing technology in Tuha Oilfield continuously breaks through the boundaries of depth, pressure, and temperature. Currently, more than 20 fracturing operations have been completed, and the success rate of fracturing operations in reservoirs deeper than 5000 meters has reached 100%, with a design compliance rate of 100%. The increasingly mature deep and ultra deep fracturing technology in Tuha Oilfield provides strong technical support for later development and production.