Study On The Efficient Throughput Development Of Fractured-cavity Carbonate Reservoirs

At present,the reserves and production of fractured-type carbonate reservoirs have a large proportion of oil and gas resources found in the world.The improvement of oil recovery is one of the key research fields in oil and gas field development.The geological characteristics of the fractured-type carbonate reservoirs are complex and the seepage mechanism is specific.The key development technology is very different from the sandstone reservoirs.At present,the mature and efficient development mode has not yet been formed.Taking Tahe M as an example,the quasi-continuum medium geological characteristics is re-understood through the static and dynamic correlation analysis method and the numerical simulation method.Based on the geological characteristics of re-understanding,typical well water injection Huffn and gas Huff and development results are analyzed.Moreover,well site selection principle is summarized.On this basis,the reservoir numerical simulation method is employed to optimize the design parameters and the prediction of the development effect of the typical wells,providing the guidance for the field construction.The main results and conclusions are as follows:(1)The development of fractures in carbonate reservoirs is complex,especially in the vertical direction of the wellbore.The development of the matrix in the plane of the well leads to the disconnection of the fractured cave;the vertical development of the interlayer;the size of the upper and lower vertical water body and the development scale of the fracture-cave unit in the plane both influence the energy of the fracture-cavity unit.By means of numerical simulation,the connecting correlation of fracture-cave and the distribution of residual oil could be depicted.It is found that the near-local control of the hole and the long-distance communication of the fracture are features of the reservoir.The whole quasi-continuum medium and the local discontinuous medium are prominent.The remaining oil distribution has both the overall regularity and the great difference between the wells,later of which is more prominent.This determines the diversity of the parameters for the gas injection Huff.(2)The principle of water injection and stimulation well selection is as follows.The fractures shall be well developed in the reservoir;there should be no bottom water body or the water body is poor;the water production in the oil well shall be low.Gas well stimulation well selection principle:there are sufficient energy at the bottom of the reservoir body of water;wells around the local are well developed.(3)The optimal oil displacement scheme of CY1 well in near-constant volume reservoir is:injection medium nitrogen,gas injection rate 2600 m~3/h,gas injection rate80,000 m~3,siltation time 26 days,liquid production rate 40 m~3/d.The optimal oil displacement scheme for CY2 well of non-constant volume reservoir is:using nitrogen gas and water as the injection medium,gas injection rate of 4200 m~3/h,gas injection amount of 500,000 m~3,boring time of 25 days,liquid production rate of 60 m~3/d.