Liquid–Solid Phase-Change Autogenous Proppant Fracturing Fluid─Phase-Change Behavior Research and Field Application

Abstract

Hydraulic fracturing is an important technology for the stimulation of oil and gas reservoirs. In recent years, a new technology called self-generated proppant fracturing that abandons the traditional "sand-carrying" mode has become a research hot spot. This technology can solve many deficiencies and limitations of a conventional fracturing technology, so it has been widely studied by scholars at home and abroad. This article studies the phase-change behavior of the self-generated proppant fracturing fluid system for this new technology, specifically analyzing the effects of temperature, time, and accelerants on the phase-change behavior and conducting on-site applications. The research shows that (1) the phase-change behavior can be divided into three parts: initiation of phase-change, solid production, and pressure-resistant solid formation. Tertiary amines were selected as the best accelerant for the new fracturing fluid system to control the time and temperature of phase-change. (2) The accelerant can reduce the phasechange temperature with a non-linear trend. (3) When the temperature is below 40 °C, the dosage of the accelerant is more than 0.6%; when the temperature is in the range of 40−60 °C, the dosage of the accelerant is about 0.4−0.6%; when the temperature is higher than 80 °C, the accelerant dosage design should be less than 0.2%. (4) Through on-site application, it has been confirmed that the new fracturing fluid system is feasible for normal construction under the existing construction conditions and effective for reservoir transformation. Under the same renovation scale, interval, and production system, the daily gas production of the well (2.23 × 10 4 m 3 /d) which used the new fluid system is higher than the adjacent wells (1.68 × 10 4 m 3 /d) according to production data.