Study On Identification Method Of Fracture Distribution In Low Permeability Reservoirs

It is considered that fractures are important factors that affect the development oflow-permeability reservoirs. With the reservoir development, fractures not onlyintensify the formation heterogeneity, but also constantly impact on reservoirproduction. On account of the lack of systematic research on the fracture distributionin the early development, adverse situation that well network not matching, injectedwater incursion, rapid increase of the water consumption and decline of productionhave arisen.In the research, dynamic data of production are used to identify fractures andhigh permeability zones, which instruct distribution regulation of the fractures andhigh permeability zones in low permeability reservoirs, and the relation betweencharacteristic of water driving and regulation.1. It is indicated by the research on geological features and development statusthat reservoir rock is mainly medium-grained fine-grained sandstone and finesandstone which are mainly composed of subaqueous distributary channel, whosebanded distribution extends from northwest to southeast. That well sorted pore-throat,low porosity and permeability of Reservoirs, and advanced injection mode ofproduction laid the foundation for identification of fractures and high permeabilityzones.2. It is researched that characteristic of oilfield development, which includedeliverability and water flooding effect, is influenced by fracture distribution inflooding pattern, especially the width, length and permeability of fracture inLiumaoyuan area as an example.3. Some indexes relating to the fractures and high permeability zones areobtained by analyses of reservoir engineering theory, gray correlative theory andproduction formula transformation. Indexes of connectivity and permeability betweenwells in actual performance are used to identify fracture and high permeability zones.To ensure the accuracy of calculation, four methods are adopted as follows: ratecorrelation, the quantitative calculation of the dynamic data, the inter-well penetrationanalysis and multiple parameters discrimination. All the methods are convenient topractice and to make division by technical boundaries, and they could also be widelyused in the research of fracture and high permeability zones.4. Referring to dynamic data of production, fractures are preliminary identifiedby multiple parameters discrimination method. Then they are sophisticatedlyidentified by rate correlation, the quantitative calculation of the dynamic data, and theinter-well penetration analysis. Finally distribution regulation of high permeabilityzones is obtained that the zones are mainly in the junction of central and north/southstudy area, and nine fractures are developed that mostly have east-west extensionexcept the two fractures in central area.