石油钻探技术
石油鑽探技術
석유찬탐기술
PETROLEUM DRILLING TECHNIQUES
2015年
4期
19-24
,共6页
宫智武%张亮%程海清%刘延民%任韶然
宮智武%張亮%程海清%劉延民%任韶然
궁지무%장량%정해청%류연민%임소연
天然气水合物%海洋钻井%井控%分解动力学
天然氣水閤物%海洋鑽井%井控%分解動力學
천연기수합물%해양찬정%정공%분해동역학
natural gas hydrate%offshore drilling%well control%dissociation dynamics
为分析天然气水合物分解对海洋钻井安全的影响,根据海底天然气水合物特征,结合天然气水合物分解动力学和热力学条件,研究了不同钻井工况下天然气水合物分解产气规律,估算了天然气水合物分解后的产气量。结果表明,在钻进天然气水合物层过程中,天然气水合物分解产气速率和累计产气量逐渐增大;在天然气水合物饱和度一定的情况下,近井天然气水合物层内的天然气水合物完全分解产气量与井身轴向半径呈平方关系;随着钻井液与天然气水合物层温差增大,天然气水合物分解速率呈指数增长;浅水区钻遇天然气水合物层易导致其分解,随着水深增加或井筒压力增大,天然气水合物分解越来越困难。研究表明,钻穿天然气水合物层时,提高钻进速度可减少天然气水合物分解;钻井过程中应根据钻前预测结果调整钻井液温度和密度来控制天然气水合物分解,同时采取必要的井控措施,以保证在适当的天然气水合物分解产气条件下安全钻进。
為分析天然氣水閤物分解對海洋鑽井安全的影響,根據海底天然氣水閤物特徵,結閤天然氣水閤物分解動力學和熱力學條件,研究瞭不同鑽井工況下天然氣水閤物分解產氣規律,估算瞭天然氣水閤物分解後的產氣量。結果錶明,在鑽進天然氣水閤物層過程中,天然氣水閤物分解產氣速率和纍計產氣量逐漸增大;在天然氣水閤物飽和度一定的情況下,近井天然氣水閤物層內的天然氣水閤物完全分解產氣量與井身軸嚮半徑呈平方關繫;隨著鑽井液與天然氣水閤物層溫差增大,天然氣水閤物分解速率呈指數增長;淺水區鑽遇天然氣水閤物層易導緻其分解,隨著水深增加或井筒壓力增大,天然氣水閤物分解越來越睏難。研究錶明,鑽穿天然氣水閤物層時,提高鑽進速度可減少天然氣水閤物分解;鑽井過程中應根據鑽前預測結果調整鑽井液溫度和密度來控製天然氣水閤物分解,同時採取必要的井控措施,以保證在適噹的天然氣水閤物分解產氣條件下安全鑽進。
위분석천연기수합물분해대해양찬정안전적영향,근거해저천연기수합물특정,결합천연기수합물분해동역학화열역학조건,연구료불동찬정공황하천연기수합물분해산기규률,고산료천연기수합물분해후적산기량。결과표명,재찬진천연기수합물층과정중,천연기수합물분해산기속솔화루계산기량축점증대;재천연기수합물포화도일정적정황하,근정천연기수합물층내적천연기수합물완전분해산기량여정신축향반경정평방관계;수착찬정액여천연기수합물층온차증대,천연기수합물분해속솔정지수증장;천수구찬우천연기수합물층역도치기분해,수착수심증가혹정통압력증대,천연기수합물분해월래월곤난。연구표명,찬천천연기수합물층시,제고찬진속도가감소천연기수합물분해;찬정과정중응근거찬전예측결과조정찬정액온도화밀도래공제천연기수합물분해,동시채취필요적정공조시,이보증재괄당적천연기수합물분해산기조건하안전찬진。
When subsea natural gas hydrate (NGH) dissociation is encountered ,offshore drilling safe-ty is notably influenced .Gas production performances of NGH were analyzed and gas production after hy-drate deposition was estimated under different drilling conditions according to the dynamics and thermody-namics of NGH dissociation . The calculations were based on the fundamental characteristics of subsea NGH ,which provided the basis for evaluating quantitatively the influence of natural gas hydrate dissocia-tion on the safety of offshore drilling .The results showed that as drilling proceeded through hydrate bear-ing zones ,gas production rate and cumulative gas production of hydrate dissociation tends to rise ,and that the gas production was in a squared exponential relationship with the NGH dissociation radius under cer-tain NGH saturation .NGH dissociation rate rose exponentially with the increase of the temperature differ-ence between drilling fluid and NGH sediment ,and drilling through hydrate layers in shallow water tended to break it down and as water depth and wellbore pressure rised ,NGH dissociation became more difficult . Increasing the drilling rate was preferable for reducing NGH dissociation when drilling through hydrate layers .It was demonstrated that NGH control during offshore drilling should focus on NGH prediction be-fore drilling ,and that drilling fluid density and temperature adjustment and essential well control measures should be taken to ensure drilling safety under the condition of certain gas hydrate decomposition.