高温高压油藏井壁沉淀物成因研究——以准噶尔盆地高探1井为例

油气藏开采过程中出现的井壁沉淀物会产生一系列地质和工程问题。以中国陆上油气勘探最近取得重大突破的准噶尔盆地南缘高探1井为例，针对高温高压条件下原油开采过程中井壁出现的大量黑色固体不溶沉淀物，通过对该沉淀物进行系统的岩石学和地球化学分析，包括族组分、气相色谱、液相色谱、含蜡量及热解实验等，明确了沉淀物的组成，进而探讨了其成因与意义。结果表明，高探1井井壁沉淀物由可溶有机质和泥粉砂质组成，其中可溶有机质主要由沥青质组成，泥粉砂质以细粉砂为主。高探1井原油开采过程中，从地层到井筒，温度和压力迅速下降，其轻质组分优先分逸流出，原油动态稳定体系被破坏，造成溶解于原油中的沥青质析出、絮凝，并吸附在井壁上，在此过程中，井底的泥沙随流体流动混入沥青析出物中，一起长大堆积。这可能是高温高压条件下油气开采过程的普遍现象，需筛选强极性沥青分散剂来增加原油体系稳定性，对已结垢的井筒采用强极性试剂进行化学清洗，增加井底滤网，减少砂泥固体颗粒。 

Origin and significance of wellbore sediment in reservoir development: a case study of well Gaotan 1 in Junggar Basin

During the development of oil and gas reservoirs, wellbore sediment will bring a series of problems, so it is important to identify the cause of wellbore sediment. The discovery in well Gaotan 1 is an important milestone in the history of oil and gas exploration in the Junggar Basin. However, with the exploitation of crude oil in this well, a large amount of black solid insoluble sediment blocked the wellbore. The composition of the sediment was clarified by various experimental analysis methods, such as group component analysis, gas chromatography, liquid chromatography, wax content analysis and pyrolysis experiments. The results allowed the study of the formation mechanism of the solid-phase sediment in well Gaotan 1 and the development of site control measures. The sediment in well Gaotan 1 is composed of soluble organic matter (mainly asphaltene) and silty sand (mainly fine silt). In the process of crude oil exploitation, the temperature and pressure of crude oil decrease from stratum to wellbore, and the light components in crude oil are preferentially separated and flow out, destroying the dynamic stability of the crude oil, and asphaltene dissolved in the crude oil to precipitate and flocculate, and finally to be adsorbed on the pipe wall. At the same time, silty sand at the bottom of the well is mixed with the asphalt precipitate with fluid flow, and grows with asphalt precipitate. This may be a common phenomenon in the oil and gas production process under high temperature and high pressure conditions. It is necessary to choose strong polar asphalt dispersants to increase the stability of the crude oil system, and use strong polar reagents for chemical cleaning of the scaled wellbore. More bottom hole filters are required to reduce sand and mud solid particles.