吉林大学学报（地球科学版）
吉林大學學報（地毬科學版）
길림대학학보（지구과학판）
JOURNAL OF JILIN UNIVERSITY(EARTH SCIENCE EDITION)
2015年
1期
198-206
,共9页
横观各向同性%泥页岩%斜井眼%坍塌压力%井壁稳定%钻井
橫觀各嚮同性%泥頁巖%斜井眼%坍塌壓力%井壁穩定%鑽井
횡관각향동성%니혈암%사정안%담탑압력%정벽은정%찬정
transversely isotropy%mudstone/shale%deviated borehole%collapse pressure%borehole stability%drilling
在以泥页岩为目标储层的非常规油气藏水平井开发中，钻遇井壁的稳定性问题突出，一方面是由于在设计钻井液密度时简单采用各向同性介质模型和 Mohr-Coulomb 强度准则，另一方面则是由于选用的钻井液性能欠佳，难以保证建井全过程的井壁稳定。为此，将地层视为横观各向同性介质，采用 Mogi-Coulomb 强度准则判别岩石基体和层理面的稳定性，同时考虑泥页岩水化作用对岩石力学强度参数的影响，建立了水敏性地层井壁稳定分析模型，分析了坍塌压力随井斜、方位、钻井液性能、钻井时间等因素的变化规律。研究结果表明：对于具有显著层理面结构的泥页岩地层，采用横观各向同性模型比各向同性介质模型更能描述强度的各向异性；采用 Mogi-Coulomb 准则比 Mohr-Coulomb 强度准则得到的坍塌压力值与实际吻合程度更高，在保证井壁稳定的前提下有利于降低钻井液密度，实现钻井提速；提高钻井液封堵能力、减小泥页岩吸水扩散能力，有利于延长坍塌周期。利用东濮、威远、焦石坝等工区多口页岩气水平井的实钻资料对本文方法进行了验证，证实本文方法确定的钻井液密度窗口下值更能满足安全钻井需求。
在以泥頁巖為目標儲層的非常規油氣藏水平井開髮中，鑽遇井壁的穩定性問題突齣，一方麵是由于在設計鑽井液密度時簡單採用各嚮同性介質模型和 Mohr-Coulomb 彊度準則，另一方麵則是由于選用的鑽井液性能欠佳，難以保證建井全過程的井壁穩定。為此，將地層視為橫觀各嚮同性介質，採用 Mogi-Coulomb 彊度準則判彆巖石基體和層理麵的穩定性，同時攷慮泥頁巖水化作用對巖石力學彊度參數的影響，建立瞭水敏性地層井壁穩定分析模型，分析瞭坍塌壓力隨井斜、方位、鑽井液性能、鑽井時間等因素的變化規律。研究結果錶明：對于具有顯著層理麵結構的泥頁巖地層，採用橫觀各嚮同性模型比各嚮同性介質模型更能描述彊度的各嚮異性；採用 Mogi-Coulomb 準則比 Mohr-Coulomb 彊度準則得到的坍塌壓力值與實際吻閤程度更高，在保證井壁穩定的前提下有利于降低鑽井液密度，實現鑽井提速；提高鑽井液封堵能力、減小泥頁巖吸水擴散能力，有利于延長坍塌週期。利用東濮、威遠、焦石壩等工區多口頁巖氣水平井的實鑽資料對本文方法進行瞭驗證，證實本文方法確定的鑽井液密度窗口下值更能滿足安全鑽井需求。
재이니혈암위목표저층적비상규유기장수평정개발중，찬우정벽적은정성문제돌출，일방면시유우재설계찬정액밀도시간단채용각향동성개질모형화 Mohr-Coulomb 강도준칙，령일방면칙시유우선용적찬정액성능흠가，난이보증건정전과정적정벽은정。위차，장지층시위횡관각향동성개질，채용 Mogi-Coulomb 강도준칙판별암석기체화층리면적은정성，동시고필니혈암수화작용대암석역학강도삼수적영향，건립료수민성지층정벽은정분석모형，분석료담탑압력수정사、방위、찬정액성능、찬정시간등인소적변화규률。연구결과표명：대우구유현저층리면결구적니혈암지층，채용횡관각향동성모형비각향동성개질모형경능묘술강도적각향이성；채용 Mogi-Coulomb 준칙비 Mohr-Coulomb 강도준칙득도적담탑압력치여실제문합정도경고，재보증정벽은정적전제하유리우강저찬정액밀도，실현찬정제속；제고찬정액봉도능력、감소니혈암흡수확산능력，유리우연장담탑주기。이용동복、위원、초석패등공구다구혈암기수평정적실찬자료대본문방법진행료험증，증실본문방법학정적찬정액밀도창구하치경능만족안전찬정수구。
Borehole stability in shale/mudstone strata is significant during the construction of horizontal well for unconventional hydrocarbon reservoirs,which is caused by two mainly reasons,one is the current borehole stability design model using simply isotropic media model and Mohr-Coulomb criterion,and the other is the inappropriate performance of drilling fluid.To solve this problem,a new borehole stability model for water-sensitive formation was established,which adopted transversely isotropic media model,Mogi-Coulomb criterion,and the effect of hydration to rock strength.The influence of deviation angle,azimuth,drilling fluid performance and drilling time on collapse pressure were analyzed.The results showed that transversely isotropic model was more suitable to describe strength anisotropy for laminated shale/mudstone; collapse pressure calculated by Mogi-Coulomb criterion is more consistent with drilling practice than Mohr-Coulomb,in this case,lower drilling fluid density can be used to keep borehole stability and promote rate of penetration;enhance sealing capacity and decline shale hydration diffusion capacity were helpful to extend collapse cycle.Several examples of shale gas horizontal wells drilled in Dongpu, Weiyuan and Jiaoshiba districts confirmed that the recommended method is highly reliable and effective.
