Description And Development And Utilization Of Jurassic Karloff-Oxfordian Gas Reservoirs In The Biepi Gas Field On The Right Bank Of The Amu Darya

After opened the upper Jurassic Callovian-Oxfordian reservoir of the Turkmenistan Amu Darya right bank area in Bereketli-Pirgui gas field,strong blowout suddenly occurred from several wells which caused borehole abandonment,what's worse,massive natural gas resource waste and environmental pollution seriously affected the development of Bereketli-Pirgui gas fields at the same time.Based on multi wells drilling and logging data?principles of carbonate and reservoir geology?drilling?seismic and logging interpretation,the paper comprehensively analyzed the characteristics of the the upper Jurassic reservoirs in Bereketli-Pirgui gas field and described the gas reservoir formation,reservoir,gas reservoir type,gas reservoir distribution and finally designed a applicable development and utilization project.It is hoped that this research can effectively reduce the drilling risks and increase the output of gas field development.The stratigraphic sequence of the field from botton to top was as follows:Jurassic?Cretaceous?Paleogene and Neogene,among them,the upper Jurassic Callovian-Oxfordian stage has developed from the bottom up to six layers,the X VI layer,the X V a2 layer,the??z layer,the ??a1 layer and the ??hp layer,specifically,the limestone in ??hp???a1 and ??a2 are the main reservoirs of the upper Jurassic Callovian-Oxfordian stage;the sedimentary environment of Callovian-Oxfordian stage in Bereketli-Pirgui gas field is carbonate rock gentle slope model.The structure of the field was a large anticline,it had two local high points:P-21 and P-23 well area,the structures of different small layers(?? hp???z and ??)were inherited,and their basic structural characteristics were similar with each other,all of them were anticline structure.There were 12 faults in this area:fault?,fault?,fault?in total 3 strike slip faults and 9 reverse faults.The main reservoir rocks in Bereketli-Pirgui gas field were bioclastic limestone,bioclastic rock,sand crumb limestone and dolomitization limestone,longitudinally,they were mainly grown in ?? hp???a1 and ??a2 layer,the thickness of reservoir rocks varied greatly from 7m to 69m,and mainly located in P-23 wells area.The reservoir was generally poor with low-middle porosity and low permeability;the storage space was mainly composed of pores and fractures,and the pore structure was identified as small pore throat type,the storage space type is fissure-pore.The gas reservior type was lithologic to structural type with edge and bottom water.The main body belonged to the abnormal high pressure and normal temperature system,it had 4 gas water systems,the gas area was 126.7km2.Gas reservoirs mainly distributed in the ??hp and ??ai layers vertically and in the B-22?P-21 wells area on the plane.In view of the characteristics of abnormal high pressure in the reservoir of the Callovian-Oxfordian reservoir,the deep development and pressure reduction method was adopted,and B-P-1D,B-P-2D,B-P-3D and B-P-4D development wells were deployed.In addition,the gas reservoir had been transported from the wellbore to the Cretaceous Santonian stage which also had an abnormal high pressure.Shallow wells were used to reduce the pressure and deployed Q-1 and Q-2 development wells.Finally,the effect of the governance was remarkable.