Research On Hydraulic Fracture Interpretation In Low Permeability Reservoirs Based On Micro-seismic Monitoring And In-situ Stress Analyzing

In recent years, reservoirs in low permeability are becoming an important part ofincreasing oil production in the world. The low permeable petroleum’s explorationand development is difficult due to their characteristics with “three lows”(lowabundance, low voltage and low yield). Currently, micro-seismic monitoringtechnology of hydraulic fracturing is a widely used and effective method for enhancedhydrocarbon recovery from low permeable reservoirs at home and abroad. Accurateaccess to the orientation and morphology information of hydraulic fracture mayoptimize the pattern arrangement, optimize water injection scheme and assess theproduction of oil and gas etc. It will promote petroleum’s exploration anddevelopment effectively. During hydraulic fracturing on the spot, accurately grasp thehydraulic fracture morphology is essential. At present, in spite of a lot of work hasbeen carried out on hydraulic fracture monitoring at home, but there is less researchon fracture interpretation. This paper aims at explaining the orientation and geometryof hydraulic fracture accurately. This paper depicts the outline of hydraulic fracture,determines the direction of fracture extension according to combining stress analyzingwith the source location of micro-seismic monitoring inversion. It also makes areasonable explanation for hydraulic fracture and the method of hydraulic fractureinterpretation presented in this paper which is applied to hydraulic fracturing on siteachieves the desired effects.This paper focuses on the topic and its significance analyzing the currentresearch of hydraulic fracture monitoring technology and micro-seismic fracturemonitoring technology. After the comparison of fracture monitoring capabilities ofdifferent methods, this paper selects micro-seismic monitoring as getting the fractureinformation.To achieve the goals in the research, this paper made a deep research onmicro-seismic monitoring technology first. We detailed the theoretical foundation,methods and system of micro-seismic monitoring technology. We also made anoverall design for the micro-seismic fracture monitoring system. This paper studied relative technologies of in-situ stress because of the close relations between hydraulicfracture parameters and ground stress distribution. Started from the basic concepts ofground stress, then, summarized its distribution, influencing factors and acquisitionmethod. This paper mainly analyzed the forming mechanisms and the factors thatimpact the morphology of hydraulic fracture, studied the forming mechanisms fromthe view of mechanics, given the conditions to produce vertical and horizontalfracture respectively in theory. Among the numerous factors which influence fracturemorphology, this paper systematically analyzed how in-situ stress, fault plane, naturalfractures and the pressure curves of bottom-hole influence the morphology ofhydraulic fracture. Finally, aimed at the micro-seismic monitoring experimentconducted in Shanxi loufan, in-situ stress on the fracture area was analyzed in detail.The extending direction and outline of the hydraulic fracture was determined bycombining in-situ stress analyzing with results of micro-seismic monitoring. We alsocalculated the hydraulic fracture parameters. The hydraulic fracture orientationanalyzed by in-situ stress is consistent with which is obtained by micro-seismicmonitoring in the fracturing experiment on site.