Feasibility evaluation on UGSs rebuilt from low-permeability sandstone gas reservoirs with water:Examples from Xujiahe 2 gas reservoirs,Zhongba gasfield,Sichuan Basin
It is rather unusual and complex for underground gas storages(UGSs)rebuilt from low-permeability gas reser-voirs with water.To provide guidance for feasibility evaluation on the rebuilding from similar reservoirs,the second mem-ber of Xujiahe Formation(Xujiahe 2 Member),Zhongba gasfield,Sichuan Basin,was taken as an objective to clarify its geological feasibility in UGS construction.And then,some dynamic characteristics were summed up,such as water inva-sion and waterbody scale.Thirdly,by means of relative-permeability experiments on cores and numerical simulation,both rebuilding feasibility and effective storage capacity were discussed.Finally,one method was created for this feasibility eval-uation.Results show that(ⅰ)regional faults and roof or floor enjoy better sealing capacity;(ⅱ)the mobilization ratio of res-ervoir space is still able to maintain at a higher level;(ⅲ)all the gas reservoirs represent weak to medium water driving with edge and bottom water in subactive to inactive state,which exerts less influence on the main UGS site;and(ⅳ)static and dynamic characteristics suggest that both pure gas area and gas-water transitional area in the main structure are avail-able for UGS construction.In conclusion,rebuilding one UGS in Zhongba gasfield from Xujiahe 2 gas reservoirs is feasi-ble.What's more,the effective storage capacity is 106.80×108 m3 under the original formation pressure of 27.25 MPa.
Sichuan BasinLow permeability,Gas reservoir with waterUnderground gas storageZhongba gasfieldStor-age capacity
NETL
NSTL
万方数据
