Determination of reservoir characteristics from transient pressures created by underbalanced perforating can enable an operator to decide whether a well is commercially productive before permanent completion. Several techniques exist to analyze such data. In this work, closed-chamber testing and log-log-and Cartesian-plotted short producing times are used to analyze data collected from a multiwell project in the Gulf of Mexico. Pressure data were obtained from underbalanced perforating and backsurge-washing treatments. Results of these analyses compared favorably with buildup tests performed after the wells were completed.
Determination of reservoir characteristics from formation pressure created by underbalanced perforating may enable an operator to decide whether a well is commercially productive prior to permanent completion. With the use of several existing techniques, it is possible to analyze such data. With closed chamber testing techniques, wellhead pressures are used to calculate variable sandface rates during and shortly after the well is underbalance perforated. Superposition is employed to create a rate-time function for plotting with bottom hole pressure data. The straight-line portion of the pressure versus ratetime function plot can be fitted using linear regression to solve the radial flow equation. Calculated parameters include effective permeability, skin effects and initial reservoir pressure. Also presented, is a method proposed by Soliman to analyze short producing time data. Delta pressure versus total time data is plotted on a Log-Log graph where the time axis combines producing time with build up time. A negative one (−1) slope on this plot indicates the existence of radial flow, from which reservoir characteristics can be calculated if the flow regime is known. A cartesian plot can be used to estimate initial reservoir pressure. This paper illustrates the use of the aforementioned techniques on data collected from a multi-well project in the Gulf of Mexico. Analyses of oil wells were investigated. The results of these analysis methods for oil cases are compared with buildups performed after the wells were completed. These analysis techniques have also been applied to formation back surge data with similar results.
Evaluation of cement placement is an important part of the majority of deepwater wells. Cement placement confirmation is an important step following a cementing operation. More than one technique can be used to provide information about the top of cement (TOC) and about the depth interval of a good bond between the formation and the casing. Determining the length of annular cement coverage, which is an indication of correct cement placement, is useful knowledge before drilling and/or completion operations can proceed. The requirement for additional and improved cement evaluation techniques is greater now than ever before. A variety of methods can be used to evaluate cement placement. The routine approach after a casing or liner cement job uses a job chart to calculate lift pressure and actual vs. predicted system pressure. These data enable an estimate of cement height in the annulus to be made, but they do not confirm the TOC. These methods vary in accuracy and difficulty, depending on well conditions. Common TOC evaluation methods in specific wellbore casing/liner sections typically require running a temperature survey or cement bond log (CBL) sensors/systems on a wireline. These operations use the rig's critical path time for each wireline run, which can add risk or difficulties, depending on the well trajectory. In addition, cement bond evaluation for large diameter casing can be technically challenging because it can reach the upper threshold measurement limitations for conventional wireline-conveyed CBL tools. Many operators now use logging-while-drilling (LWD) sonic sensors for compressional and shear data acquisition in openhole environments. Using the same sonic systems, with minimal additional rig time, logging data acquired through the casing/liner strings while running a drilling or clean out assembly can be evaluated to confirm the TOC. This paper demonstrates how LWD sonic technology can provide confirmation of the TOC, saving a considerable amount of rig time, as compared to performing a dedicated wireline evaluation run or potentially unnecessary cement squeeze operations. The paper presents and discusses Gulf of Mexico (GOM) case studies. Based on various specific challenges, through correct data analysis, TOC evaluation best practices are implemented to optimize the LWD acoustic data acquisition inside the casing/liner. New data examination techniques are reviewed that can be applied to different scenarios, such as TOC evaluation behind dual pipes and real-time assessment for quick data analysis turn-around. In conjunction with the case studies, the paper also provides information about the LWD cased-hole logging techniques, analysis, and results of the data application.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.