Summary: In the petroleum and gas industry, optimizing cost-effectiveness remains a paramount objective. One of the key challenges is enhancing predictive models for the rate of penetration (ROP), which are intricately tied to the delicate interplay between significant parameters and drilling efficiency. Recent research has hinted at the potential of temporal and sequential elements in drilling, but a detailed exploration and understanding of these dynamics remain underdeveloped. Addressing this research gap, our primary innovation is not just the introduction of a model but rather the employment of the attention-based long short-term memory (LSTM) network as a tool to deeply analyze the role of sequential features in ROP prediction. Beyond merely applying the model, we furnish a robust foundation for sequential analysis, detailing data processing methods and laying out comprehensive data analytics guidelines for such temporal assessments. The utilization of the LSTM network, in this context, ensures meticulous capture of real-time drilling data nuances, providing insights that are both profound and actionable. Through empirical evaluations with real-world data sets, we accentuate the vital importance of time-sequential dynamics in refining ROP predictions. Our methodological approach, tailored for the oilfield domain, is both rigorous and illuminating, achieving an R2 score of 0.95 and maintaining a relative error under 10%. This effort goes beyond simply proposing a new predictive mechanism. It establishes the centrality of sequential analysis in the drilling process, charting a course for future research and operational optimization in the petroleum and gas sector. We not only offer enhanced modeling strategies but also pioneer insights that can shape the next frontier of industry advancements.

Well deviation is a prevalent problem in deep oil and gas exploration, leading to a significant increase in drilling costs. The conventional bottom-hole assembly (BHA) anti-deviation design method does not consider the impact of the BHA structure on lateral vibration. This paper proposes an integrated BHA design method that takes into account both anti-deviation and vibration reduction. This method evaluates the BHA’s anti-deviation ability using the drilling trend angle. A negative value of the drilling trend angle indicates that the BHA can correct well deviation. A finite element linearized dynamics method is used to evaluate the lateral vibration intensity of the BHA. This method involves calculating the bending displacement caused by mass imbalance and then determining the magnitude of the bending strain energy based on this displacement. The structural factors affecting the anti-deviation ability and potential lateral vibration intensity of pendulum BHAs and bent-housing mud motor (BHMM) BHAs were studied, and field tests were conducted for verification. The research shows that for pendulum BHAs, the factor that has the greatest impact on anti-deviation ability and vibration intensity is the distance from the stabilizer to the drill bit. For BHMM BHAs, the length of the short drill collar has a significant impact on the vibration intensity. Compared with current design methods, the mechanical specific energy (MSE) of the single stabilizer pendulum BHA decreased by 12%, while the MSE of the BHMM BHA decreased by 26.4%. Both decreases indicate a reduction in vibration intensity. This study will help to further increase drilling speed while preventing well deviation.

LiuHua4-1 &LiuHua19-5 oil/gas fields are the first batch of Chinese self-developed projects using subsea production system in the Pearl River Marine Basin (PRMB) of South China Sea. We installed 10 sub-sea horizontal trees by a single hull vessel "HYSY708" and a semi-submersible "NH5" in the block, the completion execution phase was performed on Moored Mobile Offshore Drilling Units (MODU) with no prior experience in subsea completions from June 2011 to January 2014. Value creation activities were employed to raise the awareness and competence of the rig team to transform improvement opportunities into high performance goals. This paper presents an integrated completion program developed and implemented for reservoir characterization and formation evaluation in South China Sea. Completion fluid and treatment fluid were carefully selected and tested for well-specific conditions. The program used a combination of various completion techniques such as material corrosion, hydrate prevention, subsea horizontal tree installation, work string design optimization, subsea canned dual ESP completion system, intelligent well completion, emergency response in complex condition, etc. The integrated completion programs were designed and modified to meet the project delivery timeline and cost constraints, while responding to the challenge of properly testing the oil/gas reservoir. This paper also presents completion data analysis results and summarizes the encountered challenges and learned lessons from field operations. Specifically, we present field operation results and explain the key program elements. The learned lessons and gained experiences from the field operation presented here provide valuable guidance for future deep-water oil /gas exploration and development operations.