High-quality images from an LWD ultrasonic imaging tool are used to identify natural and induced fractures and optimize hydraulic fracturing practices in wells drilled with oil-based mud. A newly designed LWD ultrasonic imager was developed due to the high demand for acquiring high-quality wellbore images in oil-based mud environments where traditional resistivity tools usually do not provide the desired detailed. Characterization of natural and induced fractures, and wellbore geometry are used to identify and characterize formation characteristics just hours after the well reaches TD. This enables the timely detection of fracture dominated zones enabling optimization of the ongoing hydraulic fracturing operations. The ultrasonic imager provides 360-degree measurements of travel time and amplitude around the wellbore, taking advantage of the rotation of the drill string; the travel time measurements are used to provide a high-resolution caliper and the amplitude is used to detect formation features such as bedding planes, fractures and borehole breakouts. The image acquisition while drilling in high rate-of-penetration (ROP) and high revolutions per minute (RPM) scenarios allows the downhole logging sensor to acquire azimuthal data in a cost-efficient scenario which does not require additional rig downtime after the well is drilled. The characterization of the natural fracture network and induced fractures helps to better assess their potential interaction with hydraulic fractures and thus allowing the implementation of hydraulic fracturing practices that allow porosity and permeability enhancement in virgin areas of the field. The application of unique LWD technology which allow for timely reservoir characterization to further enhance completions optimization provides reservoir productivity enhancement without affecting drilling operations in unconventional shale reservoirs.
{"title":"Characterizing Fractures to Improve Hydraulic Fracturing Efficiency in Shale Reservoirs Through use of an LWD Ultrasonic Imager Designed for Oil-Based Mud Environments","authors":"C. Amorocho, C. Langford","doi":"10.2523/iptc-19845-ms","DOIUrl":"https://doi.org/10.2523/iptc-19845-ms","url":null,"abstract":"\u0000 High-quality images from an LWD ultrasonic imaging tool are used to identify natural and induced fractures and optimize hydraulic fracturing practices in wells drilled with oil-based mud.\u0000 A newly designed LWD ultrasonic imager was developed due to the high demand for acquiring high-quality wellbore images in oil-based mud environments where traditional resistivity tools usually do not provide the desired detailed. Characterization of natural and induced fractures, and wellbore geometry are used to identify and characterize formation characteristics just hours after the well reaches TD. This enables the timely detection of fracture dominated zones enabling optimization of the ongoing hydraulic fracturing operations.\u0000 The ultrasonic imager provides 360-degree measurements of travel time and amplitude around the wellbore, taking advantage of the rotation of the drill string; the travel time measurements are used to provide a high-resolution caliper and the amplitude is used to detect formation features such as bedding planes, fractures and borehole breakouts.\u0000 The image acquisition while drilling in high rate-of-penetration (ROP) and high revolutions per minute (RPM) scenarios allows the downhole logging sensor to acquire azimuthal data in a cost-efficient scenario which does not require additional rig downtime after the well is drilled. The characterization of the natural fracture network and induced fractures helps to better assess their potential interaction with hydraulic fractures and thus allowing the implementation of hydraulic fracturing practices that allow porosity and permeability enhancement in virgin areas of the field.\u0000 The application of unique LWD technology which allow for timely reservoir characterization to further enhance completions optimization provides reservoir productivity enhancement without affecting drilling operations in unconventional shale reservoirs.","PeriodicalId":393755,"journal":{"name":"Day 1 Mon, January 13, 2020","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124292735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Viscoelastic surfactant (VES) gels are used for well stimulation. Breakers such as ethylene glycol mono butyl ether, are compounds that reduce viscosity of VES gels, and are required after the stimulation job to prevent formation damage. The focus here was to delineate the steps involved in the breaking of a VES gel in the presence of model oils. It also aimed to determine the effect of increasing aliphatic chain length on the gel breaking rate. A sulfobetaine VES (40 g/L) was mixed with calcium chloride (600 mM) and three model oils (280 mM) in water. The model oils were n-decane, n-dodecane, and n-hexadecane. The complex viscosity (frequency-dependent viscosity) with time was measured for at most 24 hours at 10 rad.s-1 and strain of 2 % using a rheometer. The rheological experiments were conducted at 50 °C. The viscosity of the VES/oil mixtures increased with time and reached a maximum. The magnitude of the maximum viscosity was dependent on the oil. In the presence of n-decane and n-dodecane, the maximum viscosity steadily dropped for a few minutes before a sharp drop occurred. The drop continued until the viscosity was close to 1 cp. Meanwhile, n-hexadecane increased the viscosity and steadily dropped for 24 hours. The complex viscosity after 24 hours was > 150 cp. The time it took for the gel to break depended on the type of oil. The breakage time increased in the following order: n-decane