摘要
Abstract
Due to long-term water injection for development adjustment in the Daqing Oilfield,the underground pressure system has become complex,with extensive distribution of abnormally high-pressure zones within the formation.Additionally,the oil reservoirs are characterized by shallow burial depth and low ambient temperatures.These conditions reduce the hydration rate and slow down the structural development of cement slurry during the cementing process,as it is affected by low-temperature environments.Consequently,during the gelling process,the cement slurry is prone to invasion by high-pressure formation fluids,resulting in compromised sealing capacity of the cement sheath.Based on the"crystal nucleus induction"theory,this study synthesized hydrated calcium silicate using a chemical precipitation method to prepare a hydrated calcium silicate sol accelerator(designated as DQZ-1).Evaluation showed that with a DQZ-1 dosage of 2%～10%,the 8-hour compressive strength of cement cured at 40℃ increased by 39%～153%compared to neat slurry.Microscopic analysis confirmed that DQZ-1 accelerated the formation of cement hydration products,demonstrating excellent early-strength performance in low-temperature environments.To enhance both the low-temperature early strength and anti-channeling properties of the cement slurry system,hydrated calcium silicate and latex components were incorporated.However,issues such as demulsification,settling stratification,and high slurry consistency arose due to their interaction.To address these,polycarboxylate MD was selected,enabling the cement slurry to maintain low initial consistency while achieving significant early strength.Additionally,a polymer colloid X was chosen to impart excellent anti-settling properties to the system.Through rational formulation,a stable early-strength and anti-channeling emulsion composite(designated as DZK)was developed.This composite promotes oil well cement hydration,generating more hydration products.The cement slurry's performance coefficient(SPN)was lower than 3,and the static gel strength transition time was shortened by 81%compared to the neat slurry.The low-temperature early-strength and anti-channeling emulsion composite was field-tested in 23 adjustment wells in the Daqing Oilfield.It achieved a 100%cementing quality excellence rate,with 96.3%of the oil-bearing sections rated as excellent,demonstrating outstanding field application results.关键词
固井水泥浆/水化硅酸钙/胶乳/低温早强/防窜乳液/调整井/大庆油田Key words
cementing slurry/hydrate calcium silicate/latex/low-temperature early strength/anti-channeling emulsion/adjustment well/Daqing Oilfield分类
石油、天然气工程
