Down-the-hole(DTH)hammer with casing while drilling(CWD)is a technology that has been proven to be able to alleviate many of the problems faced by complex formations.However,the drill bit is suffered from rapid wear,l...Down-the-hole(DTH)hammer with casing while drilling(CWD)is a technology that has been proven to be able to alleviate many of the problems faced by complex formations.However,the drill bit is suffered from rapid wear,low drilling efficiency,and high energy consumption due to the unreasonable tooth arrangement and impact energy selection in drilling process,which affect the application effect of this technology.ABAQUS software was used for numerical simulation of rock breaking behavior under impact load with the single,three,and five teeth arrangement drill bit respectively,to improve the application effect and solve the aforementioned technical problems.Based on the calculated parameters of tooth arrangement,we designed a novel drill bit for hard rocks and provided a theoretical basis for the tooth arrangement of largediameter drill bits.展开更多
Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to ene...Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verified through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction.展开更多
BACKGROUND Fourth degree burns damage the full thickness of the skin and affect underlying tissues.Skin grafting after debridement is often used to cover the wounds of salvageable severe burns.A granulation wound can ...BACKGROUND Fourth degree burns damage the full thickness of the skin and affect underlying tissues.Skin grafting after debridement is often used to cover the wounds of salvageable severe burns.A granulation wound can be formed by drilling the skull to the barrier layer to solve the problem of skull exposure.Low oxygen levels present at high altitudes aggravate ischemia and hypoxia which can negatively impact wound healing.The impaired healing in such cases can be ameliorated by hyperbaric oxygen therapy.CASE SUMMARY We describe a patient who presented with fourth degree burns to the left temporal and facial regions upon admission in December 2018.The periosteum of the skull and the deep fascia of the face were exposed.After the first stage of debridement and skin grafting,the temporal skin did not survive well.Granulation was induced by cranial drilling,and then a local flap was transferred to cover the wound.The left temporal and facial wounds were completely covered and the patient recovered well.CONCLUSION Skin grafting and flap transfer after early debridement to cover the wound and control infection were of great significance.In the later stages of the patient's treatment,survival of the skin graft and skin flap was observed.The second stage repair was performed to achieve successful skin grafting by cranial granulation.Granulation was formed by drilling the skull,and then the wound was closed,which is suitable for cases with skull exposure and wounds with poor blood supply.We consider that hyperbaric oxygen treatment and improving tissue oxygen supply were beneficial in this patient.展开更多
This paper examines the feasibility in air drilling of transmitting down-hole signals by using microwaves. Firstly the basic theory of microwave propagation in the drill-pipe or casing was studied, including power los...This paper examines the feasibility in air drilling of transmitting down-hole signals by using microwaves. Firstly the basic theory of microwave propagation in the drill-pipe or casing was studied, including power loss, cutoff wavelength, and dust scattering. Theoretical analysis indicates that the microwave propagation distance in a cb214mm casing can easily reach 5,000 m. When the effect of dust particles is taken into account, the propagation distance decreases to 2,000 m. We conducted both laboratory experiments and field tests in casings commonly used in oil fields. The field tests show that the effective propagation distance of microwave in the casing is about 1,300 m. The experimental results do not match well with theoretical prediction, but are acceptable. In future commercial applications, by applying multiple relay amplifiers, the microwave propagation distance could be long enough for most drilling wells.展开更多
Deep shale gas reservoirs being developed by SIN OPEC are characterized by significant buried depths,high rock strengths, high temperatures and pressures, multiple layers, low ROPs, prolonged drilling time and prohibi...Deep shale gas reservoirs being developed by SIN OPEC are characterized by significant buried depths,high rock strengths, high temperatures and pressures, multiple layers, low ROPs, prolonged drilling time and prohibitoryhigh costs. All of these factors may negatively affect the economic and effective development of shale gas.Under such circumstances, existing drilling techniques for deep shale gas around the world have been reviewed to highlight technical challenges in deep shale gas drilling in China. With consideration to the previous drilling operations of SINOPEC for deep shale gas, technical solutions for deep shale gas drilling have been proposed with regard to the optimization of casing programs, enhanced drilling, trajectory control, high-density oil-based drilling fluid, cementation for deep shale gas development and other aspects. Some of these research findings have been deployed with great successes in Pingqiao, Jiangdong Block in the 2 nd Phase of Fuling Project, Dingshan Block and other blocks with deep shale gas development. Among them, Well JY-74-2 HF has had a drilling time of only54.25 d, whereas Well JY-187-2 HF has a TVD up to 4024.14 m. Relevant research results may provide valuable guidance and references for the optimization of drilling programs andthe enhancement ofdrilling efficiency for deep shale gas development.展开更多
基金Project of National Key Research and Development of China(No.2018YFC1505303).
文摘Down-the-hole(DTH)hammer with casing while drilling(CWD)is a technology that has been proven to be able to alleviate many of the problems faced by complex formations.However,the drill bit is suffered from rapid wear,low drilling efficiency,and high energy consumption due to the unreasonable tooth arrangement and impact energy selection in drilling process,which affect the application effect of this technology.ABAQUS software was used for numerical simulation of rock breaking behavior under impact load with the single,three,and five teeth arrangement drill bit respectively,to improve the application effect and solve the aforementioned technical problems.Based on the calculated parameters of tooth arrangement,we designed a novel drill bit for hard rocks and provided a theoretical basis for the tooth arrangement of largediameter drill bits.
基金support from the national projects (Grant No.: 2009ZX05009-005 and 2010CB226703)
文摘Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verified through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction.
文摘BACKGROUND Fourth degree burns damage the full thickness of the skin and affect underlying tissues.Skin grafting after debridement is often used to cover the wounds of salvageable severe burns.A granulation wound can be formed by drilling the skull to the barrier layer to solve the problem of skull exposure.Low oxygen levels present at high altitudes aggravate ischemia and hypoxia which can negatively impact wound healing.The impaired healing in such cases can be ameliorated by hyperbaric oxygen therapy.CASE SUMMARY We describe a patient who presented with fourth degree burns to the left temporal and facial regions upon admission in December 2018.The periosteum of the skull and the deep fascia of the face were exposed.After the first stage of debridement and skin grafting,the temporal skin did not survive well.Granulation was induced by cranial drilling,and then a local flap was transferred to cover the wound.The left temporal and facial wounds were completely covered and the patient recovered well.CONCLUSION Skin grafting and flap transfer after early debridement to cover the wound and control infection were of great significance.In the later stages of the patient's treatment,survival of the skin graft and skin flap was observed.The second stage repair was performed to achieve successful skin grafting by cranial granulation.Granulation was formed by drilling the skull,and then the wound was closed,which is suitable for cases with skull exposure and wounds with poor blood supply.We consider that hyperbaric oxygen treatment and improving tissue oxygen supply were beneficial in this patient.
文摘This paper examines the feasibility in air drilling of transmitting down-hole signals by using microwaves. Firstly the basic theory of microwave propagation in the drill-pipe or casing was studied, including power loss, cutoff wavelength, and dust scattering. Theoretical analysis indicates that the microwave propagation distance in a cb214mm casing can easily reach 5,000 m. When the effect of dust particles is taken into account, the propagation distance decreases to 2,000 m. We conducted both laboratory experiments and field tests in casings commonly used in oil fields. The field tests show that the effective propagation distance of microwave in the casing is about 1,300 m. The experimental results do not match well with theoretical prediction, but are acceptable. In future commercial applications, by applying multiple relay amplifiers, the microwave propagation distance could be long enough for most drilling wells.
文摘Deep shale gas reservoirs being developed by SIN OPEC are characterized by significant buried depths,high rock strengths, high temperatures and pressures, multiple layers, low ROPs, prolonged drilling time and prohibitoryhigh costs. All of these factors may negatively affect the economic and effective development of shale gas.Under such circumstances, existing drilling techniques for deep shale gas around the world have been reviewed to highlight technical challenges in deep shale gas drilling in China. With consideration to the previous drilling operations of SINOPEC for deep shale gas, technical solutions for deep shale gas drilling have been proposed with regard to the optimization of casing programs, enhanced drilling, trajectory control, high-density oil-based drilling fluid, cementation for deep shale gas development and other aspects. Some of these research findings have been deployed with great successes in Pingqiao, Jiangdong Block in the 2 nd Phase of Fuling Project, Dingshan Block and other blocks with deep shale gas development. Among them, Well JY-74-2 HF has had a drilling time of only54.25 d, whereas Well JY-187-2 HF has a TVD up to 4024.14 m. Relevant research results may provide valuable guidance and references for the optimization of drilling programs andthe enhancement ofdrilling efficiency for deep shale gas development.
