To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problem...To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problems such as leakage, collapse and sticking in slim-hole sidetracking, and difficult evaluation of remaining gas were gradually overcome, and a set of drilling and completion technology, well deployment optimization technology and geo-steering technology suitable for sidetracking horizontal wells in tight sandstone gas reservoirs have been worked out. By making full use of the old well, sidetracking horizontal wells can greatly reduce development costs, enhance the producing degree of inter-well remaining reserves, and get production 3-5 times of that of adjacent vertical wells.Its production effect is influenced by encountered sandstone length, the position of the horizontal segment in the reservoir, produced effective reservoir thickness, gas saturation, controlled reserves and fracturing effect, etc. Up to now, in Block Su10 and Su53, 12 sidetracking horizontal wells have been drilled, which have an average drilling cycle of 49 days, average horizontal section length of 689 m,average effective drilling ratio of 61.5%, average well-head pressure of 16.2 MPa, and daily output of 4.7×10~4 m^3 at the initial stage after production. By the end of 2017, the average yield increment was more than 1 000×10~4 m^3 with good effect. With the increase of low yield old wells, wells in the enrichment regions tend to be saturated and the rest gas-bearing areas are lower in grade, therefore, sidetracking horizontal well can be used for optimization of well pattern, well deployment mode and exploitation of remaining oil areas.展开更多
Organic rich dark shale of Q Formation can be found in many areas(e.g.,in the North of S Basin).The shale target stratum is easy to hydrate and often undergoes spallation.Therefore,centering the casing in the horizont...Organic rich dark shale of Q Formation can be found in many areas(e.g.,in the North of S Basin).The shale target stratum is easy to hydrate and often undergoes spallation.Therefore,centering the casing in the horizontal section of the irregular borehole is relatively difficult.Similarly,achieving a good cementflushing efficiency under complex borehole conditions is a complex task.Through technologies such as centralizer,efficient preflushing,multi-stageflushing and ductile cement slurry,better performances can be achieved.In this study,it is shown that the cementing rate in the DY2H horizontal section is 97.8%,which is more than 34%higher than that of adjacent wells.This cementing matching technology for sidetracking horizontal wells can be used to improve the cementing quality of continental shale and provides a reference for future applications in thisfield.展开更多
The scaling criteria of physical modeling of a horizontal well production are discussed. A scaled experimental model was designed and realized. The experiments of a sidetrack horizontal well production have been carri...The scaling criteria of physical modeling of a horizontal well production are discussed. A scaled experimental model was designed and realized. The experiments of a sidetrack horizontal well production have been carried out in the system, and the production curve variation is analyzed. The oil recovery of a sidetrack horizontal well production is compared with that of a vertical well, and the effect of factors such as sidetrack drilling time, water driving rate and the length of horizontal section on oil recovery are discussed. The production of a horizontal well changed both the fluid flow direction and pressure distribution in the reservoir; as a result the remaining oil in the dead oil region is recovered, and the ultimate oil output is raised.展开更多
基金Supported by the Project of Great Wall Drilling Company in CNPC(2015A25-2(2012))
文摘To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problems such as leakage, collapse and sticking in slim-hole sidetracking, and difficult evaluation of remaining gas were gradually overcome, and a set of drilling and completion technology, well deployment optimization technology and geo-steering technology suitable for sidetracking horizontal wells in tight sandstone gas reservoirs have been worked out. By making full use of the old well, sidetracking horizontal wells can greatly reduce development costs, enhance the producing degree of inter-well remaining reserves, and get production 3-5 times of that of adjacent vertical wells.Its production effect is influenced by encountered sandstone length, the position of the horizontal segment in the reservoir, produced effective reservoir thickness, gas saturation, controlled reserves and fracturing effect, etc. Up to now, in Block Su10 and Su53, 12 sidetracking horizontal wells have been drilled, which have an average drilling cycle of 49 days, average horizontal section length of 689 m,average effective drilling ratio of 61.5%, average well-head pressure of 16.2 MPa, and daily output of 4.7×10~4 m^3 at the initial stage after production. By the end of 2017, the average yield increment was more than 1 000×10~4 m^3 with good effect. With the increase of low yield old wells, wells in the enrichment regions tend to be saturated and the rest gas-bearing areas are lower in grade, therefore, sidetracking horizontal well can be used for optimization of well pattern, well deployment mode and exploitation of remaining oil areas.
基金funded by the CNPC Science and Technology Department Project(2021ZZ10-03)。
文摘Organic rich dark shale of Q Formation can be found in many areas(e.g.,in the North of S Basin).The shale target stratum is easy to hydrate and often undergoes spallation.Therefore,centering the casing in the horizontal section of the irregular borehole is relatively difficult.Similarly,achieving a good cementflushing efficiency under complex borehole conditions is a complex task.Through technologies such as centralizer,efficient preflushing,multi-stageflushing and ductile cement slurry,better performances can be achieved.In this study,it is shown that the cementing rate in the DY2H horizontal section is 97.8%,which is more than 34%higher than that of adjacent wells.This cementing matching technology for sidetracking horizontal wells can be used to improve the cementing quality of continental shale and provides a reference for future applications in thisfield.
基金This work is part of results of National Key Science and Technology Research Projects from 1995 to 2000 (Grant number 95-108-01-02).
文摘The scaling criteria of physical modeling of a horizontal well production are discussed. A scaled experimental model was designed and realized. The experiments of a sidetrack horizontal well production have been carried out in the system, and the production curve variation is analyzed. The oil recovery of a sidetrack horizontal well production is compared with that of a vertical well, and the effect of factors such as sidetrack drilling time, water driving rate and the length of horizontal section on oil recovery are discussed. The production of a horizontal well changed both the fluid flow direction and pressure distribution in the reservoir; as a result the remaining oil in the dead oil region is recovered, and the ultimate oil output is raised.
