Haddad, Mohamed (ADNOC Offshore) | Rashed Al-Aleeli, Ahmed (ADNOC Offshore) | Toki, Takahiro (ADNOC Offshore) | Pratap Narayan Singh, Rudra (ADNOC Offshore) | Gumarov, Salamat (Schlumberger) | Benelkadi, Said (Schlumberger) | Bianco, Eduardo (Schlumberger) | Mitchel, Craig (Schlumberger) | Burton, Phil (Schlumberger)
Injection of drilling waste into subsurface formations proves to be an environmentally-friendly and cost-effective waste management method that complies with zero discharge requirements. It has now become the technology of choice in offshore Abu Dhabi.
The aim of cuttings reinjection (CRI) is to mitigate risks associated with subsurface waste injection and reduce cuttings processing time and cost. In order to meet these goals, a cuttings reinjection subsurface assurance methodology was developed to improve cuttings processing and continuously monitor drilling waste injection operations.
Preparing for CRI operations required extensive drilling cuttings slurry testing to minimize processing time and develop optimum particle size distribution to reduce cost and increase the injected waste volume. The improvements were accompanied by downhole pressure and temperature monitoring of the injection well, thus facilitating analysis of injection pressures. Fracture containment was verified through a combination of pressure decline analysis, periodic injectivity test, temperature survey, and periodic modelling for fracture waste domain mapping. A backup injection well was used also as an observation well to monitor the pressure signitures in the injection formation.
More than 1 million barrels of drill cuttings and associated drilling waste have been safely and successfully disposed of into a single injection zone of CRI well over three years of operations.
The cuttings reinjection subsurface assurance method optimizes grinded cuttings particle size distribution, detects and identifies potential risks to provide mitigation options to prolong the life of the injector.
The proactive subsurface injection monitoring-assurance program was built into the fit for purpose CRI injection procedure to continually avoid injecting any rejected hard material, improve and update the process as per subsurface injection pressure responses, thus reducing processing time and cost, mitigating injection risks, and extending the injection well life.
This paper presents the unique and technically challenging cuttings slurry properties design and pressure interpretation experience learned in this project; the enhancement of cuttings processing helped increase injection volumes and an in-depth interpretation of fracture behavior which behaved like a risk-prevention tool with mitigation options. Significant enhancement was developed in slurry treatment procedures to avoid injectivity loss and maximize the disposal capacity.
Wei, Zhiyuan (CGG) | Xuan, Yi (CGG) | Huang, Rongxin (CGG) | Theriot, Christian (Shell Global) | Rodenberger, Douglas (Shell Global) | Chang, Mark (Anadarko Petroleum Corporation) | Morton, Scott (Hess) | Zouari, Mehdi (Anadarko)
Summary Large spectral differences exist between streamer and ocean bottom seismometer (OBS) data, mostly due to different surface-related ghost effects - streamer data have both shot-and receiver-side ghosts, while OBS data have only the shot-side ghost. In a recent OBSstreamer time lapse study in deepwater Gulf of Mexico, we investigated three schemes of spectral matching between OBS and streamer data: conventional 1D matching of streamer to OBS, receiver deghosting of streamer data only, and full deghosting of both data sets. The study demonstrated the benefits of receiver deghosting on streamer data over 1D matching, particularly because it provided a better match between the streamer and OBS data before migration and an increased 4D signal-to-noise ratio (S/N) after migration. However, we found that shot deghosting on both surveys did not improve the 4D results; instead, the spectra of streamer and OBS, especially at lower frequencies, were more different after shot deghosting. Receiver deghosting alone on the streamer data gave the best 4D results among the three schemes.
Salehi, Saeed (University of Louisiana - Lafayette) | Hussmann, Stefanie (University of Louisiana At Lafayette) | Karimi, Moji (Weatherford) | Ezeakacha, Chinedum Peter (University of Louisiana - Lafayette) | Tavanaei, Amirhossein (University of Louisiana At Lafayette)
Wellbore stability issues are continually plaguing the industry and it is important to understand the mud properties that contribute to these issues. The effects of mud cake build up and filtration with time aids the understanding of formation damage and wellbore stability. The increase of drilling in high temperature and pressure zones (HTHP) necessitates studies that can predict filtrate invasion, and particle bridging. The most common hydraulically challenged zones are: depleted sands or intervals with very low pore pressure and fracture pressure, wellbore ballooning zones encountered in deep water drilling where surge and swab pressures could be a serious challenge, and complete lost circulation/no return zones.
Filtrate invasion and mud cake build up can be considered as primary factors controlling wellbore stability while drilling. Decreasing the near wellbore permeability by forming an ultra low mud cake can strengthen the wellbore and mitigate further lost circulation problems. Very few studies have investigated filtration and filter cake build up under HPHT situations where effect of different mud particles and bridging solids can be analyzed.
This paper focuses on experimental methods quantifying water based muds used by the industry and investigating effects on particle bridging, filtrate invasion and permeability. Then adding lost circulation material (LCM) to optimize the particle size distribution of bridging solids as needed. To show the particle bridging effect, high temperature and pressure (HTHP) filtration tests were conducted at different time steps on sandstone cores of 50 mD and 750 mD. The Scanning Electron Microscope (SEM) analysis conducted on the cores presents an expected trend of particle invasion with depth and time, internal mud cake formation in the porous media, and pore plugging.
The technically challenging development of the marginal resources in the mature fields in the North Sea requires new levels of planning and execution to control the drilling process.
Over the past few years, improved dataflow between drilling rigs and shore-based operator and service providers support organizations has created a renewed interest in automated monitoring of drilling parameters. Development of data transmission systems like InterACT and data formats like WITSML have initiated the search for and the development of new sensors that can be used for automated real-time monitoring of critical drilling fluid parameters.
Increased focus on HSE in general and the use of harmful test chemicals, vapors and the risk of explosions in particular also has been an important driver for this development. Introducing a level of automation described in this paper can reduce by 70-80% the exposure time of fluids engineer in the rig laboratory without compromising service quality.
Moreover, the development and use of advanced hydraulic simulation programs frequently employed for extended reach drilling and managed pressure drilling (MPD) have increased the focus on more reliable and more frequent operational inputs. The precision of modern simulation software represents a sharp contrast to the current practice of manual rig testing and reporting.
This paper details the selection of fluid parameters considered most important for automation. The authors will describe the sensors developed for monitoring the most important parameters, including Electrical Stability (ES), density, temperature, water content in invert emulsion drilling fluid, XRF elemental analysis, in-line particle size distribution (PSD) and full 3D rheology tests. The parameters that could be monitored with existing sensor technologies used in other industries will be discussed, as well as those requiring development based on current field equipment. In addition, the paper will describe the installation and first field experiences with a full range of automated instruments on various rigs in the North Sea.