新型油井水泥触变剂的研究与应用

常规油井水泥触变剂常存在触变性不够强、影响施工安全、综合性能欠佳等问题。为此，通过将合成聚合物和超细无机材料以2∶3的比例复配，开发出一种新型油井水泥触变剂BCJ-200S，研究了其应用性能。结果表明，该触变剂可显著提高水泥浆触变性，且温度影响小，90℃加入1.5% BCJ-200S后水泥静浆静置10 min的胶凝强度从2.3 Pa增加到61.0 Pa，静置前后的φ₃₀₀读数分别为206和210，再静置10 min胶凝强度为61.3 Pa，其触变结构可逆性良好，对水泥浆稠化、失水、强度等性能没有产生不良影响；其还可改善水泥石的力学性能，增强水泥石抗破坏能力；另外，配伍性研究结果表明，该触变剂具有良好的现场适应性。其在大港油田官38-22油井进行了首次应用，该井采用12 m3触变水泥浆封堵Ng2出水井段，一次封堵成功，最高挤注压力达16 MPa，钻塞后对封堵层试压8 MPa合格，解决了该井出水难题。 

Study and Application of a Novel Thixotropic Additive for Oil Well Cement

Conventional thixotropic additives used in oil well cement have some shortages such as weak thixotropy and poor overall performance which negatively affecting operation safety. A new thixotropic additive BCJ-200S has been developed to overcome these shortages. BCJ-200S is made of a synthetic polymer and an ultra-fine inorganic powder in a ratio of 2:3. Studies on the performance of BCJ-200S showed that it remarkably improves the thixotropy of oil well cement. A cement slurry treated with 1.5% BCJ-200S had 10 min gel strength increased from 2.3 Pa to 61.0 Pa after standing 10 min. The φ300 readings of the cement slurry before and after standing were 206 and 210, respectively. The gel strength of the cement slurry became 61.3 Pa after standing 10 min more. These data indicate that the cement slurry treated with BCJ-200S had good reversible thixotropy, and BCJ-200S did not negatively affect the thickening, filtration and strength performances of the cement slurry. Laboratory studies also showed that BCJ-200S helps improve the mechanical performance of set cement and enhance the resistance of set cement to breaking. BCJ-200S is also well compatible with other commonly used oil well cement additives. BCJ-200S was first used on the well Guan38-22 in Dagang oilfield. The Ng2 water section in the wellbore was sealed off with 12 m3 thixotropic cement slurry successfully on the first try. The maximum squeezing pressure used to pump cement slurry was 16 MPa. After drilling out the cement plug, the wellbore section sealed was pressure tested with 8 MPa, with no leaking. With the use of BCJ-200S, water cut was finally suppressed.