Sponsor(s):Sinopec Research Institute of Petroleum Engineering
6 issues per year
Petroleum Drilling Techniques is supervised by China Petrochemical Corporation (Sinopec Group), sponsored by Sinopec Research Institute of Petroleum Engineering. It aims to serve the authors and readers interested in the field of petroleum, and promote the development of petroleum engineering technology. Its scope covers oil exploitation, oil drilling, and oil drilling equipment. Petroleum Drilling Techniques is included in CSCD, CA, EBSCO. Impact factor is 1.650.
Editor-in-Chief: Ma Kaihua
Petroleum Drilling Techniques,2022,No. 03
According to the similarity principle, a device for sand-carrying tests was developed to determine the sand-carrying performance of supercritical CO2 in the horizontal annulus and analyze the effects of key operating parameters on the sand-carrying performance. The device was employed to explore the influence of the injection mass flow, sand concentration, outlet pressure, and fluid temperature of supercritical CO2 on the sand migration in the horizontal annulus. The results showed that supercritical CO2 could effectively carry sand in the horizontal annulus by means of suspension transport, and the increase in its mass flow could enhance the turbulence intensity of the fluid in the annulus and improve the sand-carrying effect by suspension transport. In a high sand concentration, sand beds were likely to occur at the bottom of the annulus, which reduced the open area and raised the sand transport velocity. Under the same injection condition, the sand transport velocity in the annulus decreased with the increase in outlet pressure, but the reduction is gradually lowering. In addition, a rise in fluid temperature was conducive to the accumulation reduction of sand in the annulus in an appropriate temperature range. The research results can provide a reference for optimizing the key construction parameter design in drilling and fracturing with supercritical CO2.
Fracturing Technologies with Profile Control and Water Shutoff for Medium and High Water-Cut Wells in Ultra-Low Permeability Reservoirs of Changqing Oilfield
Petroleum Drilling Techniques,2022,No. 03
Due to the influence of the high-permeability zone, the water cut will increase and reservoir stimulation results are poor when conventional refracturing is implemented in the ultra-low permeability reservoirs of Changqing Oilfield at the medium and high water-cut development stage. Focusing on the long-term injection-production development practices of typical reservoirs and infill well production data, this paper uses 3D geological modeling to analyze the stimulation mechanism of fracturing with profile control and water shutoff in medium and high water-cut oil wells. The influence of fracturing parameters on the effect of repeated stimulation was studied, and a refracturing concept hinging on “profile control and water shutoff in the pad adding stage to control water cut and dynamic multistage temporary plugging fracturing to improve single-well production” was advanced. PEG-1 gel was developed through laboratory experiments and when the mass fraction of its main agent achieved 5%–10%, gel strength would be maintained at a high level. With an optimal injection flow rate of 1.5 m3/min and an injection volume of 300–600 m3, the high-permeability zones at the fracture depth of 40–80 m could be effectively plugged. In this way, the dynamic multistage temporary plugging fracturing technology was optimized. As a result, the net pressure in the fractures was increased to above 5.0 MPa, fractures extended from the low-stress zone to the high-stress zone, and the production of the oil remaining laterally was thereby produced. Field test results showed that average oil production improvement per well was 1.07 t/d and water cut was reduced by 9 percentage points after the measure was implemented, which indicated that the goal of increasing oil production while controlling water was accomplished by refracturing the medium and high water-cut wells. The proposed fracturing technology with profile control and water shutoff provides a new technical concept for the repeated stimulation of medium and high water-cut wells in ultra-low permeability reservoirs of Changqing Oilfield.