How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth ...How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth can be predicted by the maximum hydraulic extension depth prediction model. To overcome the disadvantage that previous prediction model did not consider the effects of temperature and only applies to horizontal wells, a prediction model of maximum hydraulic extension depth for ultra deep wells considering effects of temperature is established. Considering the effects of temperature coupled with the constraints of drilling pump rated pressure and rated power, the prediction result of ultra deep well's maximum hydraulic extension depth is modified. An ultra deep well developed by Sinopec in Shunbei oilfield, China, is analyzed, and its wellbore temperature profile and maximum hydraulic extension depth are analyzed and predicted. Results show that the maximum hydraulic extension depth with considering temperature is larger than that without considering temperature. With the identical depth, the higher inlet temperature and the greater geothermal gradient mean the higher drilling fluid temperatures in the drill string and annulus as well as the larger maximum hydraulic extension depth. Besides, the maximum depth decreases with the increase in drilling fluid flow rate and density, while it increases with the increase in drilling pump rated pressure and rated power. To ensure the designed depth can be reached, there exists the maximum drilling fluid flow rate and density, as well as the minimum drilling pump rated pressure and rated power. This study is important for accurately predicting the ultra deep well's maximum depth within the limit capacity of drilling pump. In addition, it also plays a major role in avoiding drilling hazards.展开更多
Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the f...Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the fact that conventional computational models for predicting circulating pressure drop are inapplicable to hydraulics design of deep wells. With the adoption of helical flow theory and H-B rheological model, a computational model of velocity and pressure drop of non-Newtonian fluid flow in the eccentric annulus was established for the cases where the drill string rotates. The effects of eccentricity, rotation of the drill string and the dimensions of annulus on pressure drop in the annulus were analyzed. Drilling hydraulics was given for an ultra-deep well. The results show that the annular pressure drop decreases with an increase in eccentricity and rotary speed, and increases with a decrease in annular flow area. There is a great difference between static mud density and equivalent circulating density during deep well drilling.展开更多
Abnormal oil casing pressure appeared in the process of test production of multiple Ultra-Deep Gas Wells in Tarim Basin. The super 13Cr oil pipe string was used to analyze the causes of pipe string failure in view of ...Abnormal oil casing pressure appeared in the process of test production of multiple Ultra-Deep Gas Wells in Tarim Basin. The super 13Cr oil pipe string was used to analyze the causes of pipe string failure in view of the oil casing channeling well during the test and blowout period. The construction process of the well was analyzed in detail. Combined with the review of the operation flow and the detection of fracture string material and fracture morphology, the causes of pipe string fracture were analyzed and calculated in detail. Through field investigation, analysis and calculation, it was found that the main cause of cracking of super 13Cr tubing in this well is the decrease of vibration natural frequency caused by excessive fluid velocity in pipe and too long span of pipe string. At the same time, the mixed failure of stress corrosion cracking and stress load interaction occurred in Cl−1 environment and other corrosion environments.展开更多
Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was establishe...Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was established to analyze dynamic change characteristics of the uplift force of drill string during the shut-in period, and then a management procedure for the uplift risk during the shut-in period after gas overflow in the ultra-deep well was formed. Cross section method and pressure area method were used to analyze the force on drill string after shut-in of well, it was found that the source of uplift force was the "fictitious force" caused by the hydrostatic pressure in the well. When the fictitious force is in the opposite direction to the gravity, it is the uplift force. By adopting the theory of annular multiphase flow, considering the effects of wellbore afterflow and gas slippage, the dynamic change of the pressure and fluid in the wellbore and the uplift force of drill string during the shut-in period were analyzed. The magnitude and direction of uplift force are related to the length of drill string in the wellbore and shut-in time, and there is the risk of uplift of drill string when the length of drill string in the wellbore is smaller than the critical drill string length or the shut in time exceeds the critical shut in time. A set of treatment method and process to prevent the uplift of drill string is advanced during the shut-in period after overflow in the ultra-deep well, which makes the risk management of the drill string uplift in the ultra-deep well more rigorous and scientific.展开更多
To deal with the exploitation difficulties of gas fields in Northeast Sichuan with deep marine strata, after researching the relative standards domestic and abroad extensively, summarizing and promoting the successful...To deal with the exploitation difficulties of gas fields in Northeast Sichuan with deep marine strata, after researching the relative standards domestic and abroad extensively, summarizing and promoting the successful experiences and failure lessons of project construction technology application scientifically, Sinopec has established an integrated technical standard system for the exploration and development of ultra deep and high sour gas fields. The system consists of 51 enterprise standards and covers 7 professions including geophysical prospecting, drilling, drilling log, well logging, gas formation test and production, sour gas gathering and transferring system, and HSE (health,safety,environment). It guides and guarantees the safe, high-quality and high-efficiency project construction effectively by means of enhancing the engineering design criterion, recommending the data processing and interpretation methods, identifying the requirements of operation and field inspection and standardizing the application of technical equipments.展开更多
基金supported by Sinopec Research Institute of Petroleum Engineering,Beijing,Chinathe National Natural Science Foundation of China (Grant No. 51821092)+1 种基金the New Technology for Design and Control of Complex Well and Cluster Well (Grant No. 2017ZX05009-003)the Key Technology of Drilling Technology and Wellbore Working Fluid(Grant No. 2016YFC0303303)。
文摘How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth can be predicted by the maximum hydraulic extension depth prediction model. To overcome the disadvantage that previous prediction model did not consider the effects of temperature and only applies to horizontal wells, a prediction model of maximum hydraulic extension depth for ultra deep wells considering effects of temperature is established. Considering the effects of temperature coupled with the constraints of drilling pump rated pressure and rated power, the prediction result of ultra deep well's maximum hydraulic extension depth is modified. An ultra deep well developed by Sinopec in Shunbei oilfield, China, is analyzed, and its wellbore temperature profile and maximum hydraulic extension depth are analyzed and predicted. Results show that the maximum hydraulic extension depth with considering temperature is larger than that without considering temperature. With the identical depth, the higher inlet temperature and the greater geothermal gradient mean the higher drilling fluid temperatures in the drill string and annulus as well as the larger maximum hydraulic extension depth. Besides, the maximum depth decreases with the increase in drilling fluid flow rate and density, while it increases with the increase in drilling pump rated pressure and rated power. To ensure the designed depth can be reached, there exists the maximum drilling fluid flow rate and density, as well as the minimum drilling pump rated pressure and rated power. This study is important for accurately predicting the ultra deep well's maximum depth within the limit capacity of drilling pump. In addition, it also plays a major role in avoiding drilling hazards.
基金supported by the National 863 Program (2006AA06A19-2)
文摘Due to the slim hole at the lower part of the ultra-deep and deep wells, the eccentricity and rotation of drill string and drilling fluid properties have great effects on the annular pressure drop. This leads to the fact that conventional computational models for predicting circulating pressure drop are inapplicable to hydraulics design of deep wells. With the adoption of helical flow theory and H-B rheological model, a computational model of velocity and pressure drop of non-Newtonian fluid flow in the eccentric annulus was established for the cases where the drill string rotates. The effects of eccentricity, rotation of the drill string and the dimensions of annulus on pressure drop in the annulus were analyzed. Drilling hydraulics was given for an ultra-deep well. The results show that the annular pressure drop decreases with an increase in eccentricity and rotary speed, and increases with a decrease in annular flow area. There is a great difference between static mud density and equivalent circulating density during deep well drilling.
文摘Abnormal oil casing pressure appeared in the process of test production of multiple Ultra-Deep Gas Wells in Tarim Basin. The super 13Cr oil pipe string was used to analyze the causes of pipe string failure in view of the oil casing channeling well during the test and blowout period. The construction process of the well was analyzed in detail. Combined with the review of the operation flow and the detection of fracture string material and fracture morphology, the causes of pipe string fracture were analyzed and calculated in detail. Through field investigation, analysis and calculation, it was found that the main cause of cracking of super 13Cr tubing in this well is the decrease of vibration natural frequency caused by excessive fluid velocity in pipe and too long span of pipe string. At the same time, the mixed failure of stress corrosion cracking and stress load interaction occurred in Cl−1 environment and other corrosion environments.
基金Supported by China National Science and Technology Major Project(2016ZX05020-006)
文摘Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was established to analyze dynamic change characteristics of the uplift force of drill string during the shut-in period, and then a management procedure for the uplift risk during the shut-in period after gas overflow in the ultra-deep well was formed. Cross section method and pressure area method were used to analyze the force on drill string after shut-in of well, it was found that the source of uplift force was the "fictitious force" caused by the hydrostatic pressure in the well. When the fictitious force is in the opposite direction to the gravity, it is the uplift force. By adopting the theory of annular multiphase flow, considering the effects of wellbore afterflow and gas slippage, the dynamic change of the pressure and fluid in the wellbore and the uplift force of drill string during the shut-in period were analyzed. The magnitude and direction of uplift force are related to the length of drill string in the wellbore and shut-in time, and there is the risk of uplift of drill string when the length of drill string in the wellbore is smaller than the critical drill string length or the shut in time exceeds the critical shut in time. A set of treatment method and process to prevent the uplift of drill string is advanced during the shut-in period after overflow in the ultra-deep well, which makes the risk management of the drill string uplift in the ultra-deep well more rigorous and scientific.
文摘To deal with the exploitation difficulties of gas fields in Northeast Sichuan with deep marine strata, after researching the relative standards domestic and abroad extensively, summarizing and promoting the successful experiences and failure lessons of project construction technology application scientifically, Sinopec has established an integrated technical standard system for the exploration and development of ultra deep and high sour gas fields. The system consists of 51 enterprise standards and covers 7 professions including geophysical prospecting, drilling, drilling log, well logging, gas formation test and production, sour gas gathering and transferring system, and HSE (health,safety,environment). It guides and guarantees the safe, high-quality and high-efficiency project construction effectively by means of enhancing the engineering design criterion, recommending the data processing and interpretation methods, identifying the requirements of operation and field inspection and standardizing the application of technical equipments.
