No abstract

Hydraulic fracturing has become a key technology for the unconventional oil and gas development. Due to the complexity of geological conditions and the limitation of monitoring technology, it is still very difficult to accurately understand the three-dimensional distribution characteristics of hydraulic fractures. Based on the acoustic emission monitoring and three-dimensional laser scanning for large scale (762 mm * 762 mm * 914 mm) hydraulic fracturing test, hydraulic fracture morphology characterization is measured. The control method of acoustic emission signal quality based on amplitude, root-mean-square phase and multi-channel contrast signal recognition was explored. A multi-parameter constrained grid search and location method was established, which significantly improved the location accuracy and realized the dynamic and static real-time characterization of hydraulic fracture space expansion under indoor conditions. The results show that: based on laser scanning technology, the detailed characterization method of hydraulic fracture morphology is established, and the fracture morphology in laboratory experiment can be improved from two-dimensional observation to three-dimensional display. Due to mutual influence of natural fracture and in situ stress field, the hydraulic fracture appears complex geometry such as turning and bifurcation. The accuracy of acoustic emission location is improved by 10%, and the consistency with the actual fracture scale reaches 95%. The processing method of acoustic emission signal in this paper can be directly used in the optimization of field microseismic monitoring to guide the evaluation of unconventional reservoir stimulation, which shows a broad application prospect.

No abstract

Abstract.In-fissure divert fracturing technology, in which diverting agent is added. It can create new branch fractures and micro fractures, increase the area of fluid-release and achieve the goal of production and injection increase. This paper introduces a new diverting agent material with different kinds of petroleum resins. A series of evaluation including compatibility, efficiency and dissolved time was put forward. The results showed that the soluble rate of this agent is from 6 h to 12h and with increasing temperature and prolonging dissolved time, soluble rate reach 96% at 110 indicated good solubility. The critical flow velocity of sand production increases more than 30 60 times with adding fiber. The highest breakthrough pressure can reach 0.5MPa in 10 cm cores containing 9 diverting agent in the fracturing fluid. Meanwhile, it has minimal impact on flow conductivity .It had good flow back after treatment the viscosity was 13-54 mPa.s.Moreover, a special instrument was introduced to evaluate the performances of fracture conductivity and diverting. More than 24 treatments with this new material in X oil field have been performed with encouraging results with an average post-fracturing rate 11m 3 /d. It has great influences on new chemical material for improving complex fractures net-work of hydraulic fracturing in tight oil and gas reservoirs.

Deep oil and gas reservoirs enjoy great opulence in resources, and yet the ultra-deep burial, high temperature, high pressure and natural fractures in reservoirs bring great difficulties to propped fracturing. Given the challenge of propped fracturing in deep reservoirs, a new cost saving and high density fracturing fluid system was developed, of which the performance was evaluated and formulation was optimized, and with this fracturing fluid system, wells that cannot be treated before, can now be effectively stimulated. The advanced fracturing fluid system has been applied to eight layers in five wells, which all proved to be successful and effective, with remarkable reservoir stimulation efficacy. The post-production in the formation testing grew twice of the pre-fracturing production, and two wells were seen gas production exceeding one million cubic meters. The advanced fracturing fluid system greatly expands the well depth range of exploration and development, and lays a solid technical foundation for implementation of propped fracturing in deep reservoirs.