An inventive application for Roller Cone (TCI) and Polycrystalline Diamond Compact (PDC) bits (all sizes) that involves reusing the bits in future wells for similar well design types. With factory drilling being carried out in one of the Gas field (among other areas in gas) with over 50 runs a year provides an excellent opportunity to utilize rerun bits, both TCI and PDC, that have a 90-95% life remaining. Using this approach provides an effective and efficient way of cost saving during drilling.
While the cost of new bits in the country is very high compared to markets outside, mainly due to logistics issues with recent and continuous enhancements in bit designs, it makes complete sense to reuse these bits; especially when a huge inventory is available due to so many rigs drilling the similar type well designs in one or similar gas fields. The main criterion is to keep a track of all sizes of bits used on all gas rigs in the area and in the tool house (warehouse). Often, a particular size bit, either TCI or PDC, is used to drill a very short interval in a particular section due to a technical reason for the bit in the well being pulled out of hole, and is almost in brand new condition. Having an up-to-date inventory of these bits from the gas rigs, the tool house, and bit vendors makes it easy to identify such bits and utilize them in new wells, which provides significant cost savings.
Using the rerun bit approach immediately takes the bit cost for that particular hole section to 0$ and so we can achieve additional drilling optimization by utilizing a mud motor in that section, i.e., 12-in., 8-3/8 in., or 5-7/8 in., and further increasing the rate of penetration (ROP) by maintaining the same cost/ft ($/ft) in the section and even breaking bit record runs. In the last few wells it has been evident that by using this approach, the cost/ft for the 12-in. section drilling in the Gas Field field is seen as low as 52% of the new bit for the same year; providing a benchmark for the field. This would not have been possible without utilizing the rerun bits from previous wells. This approach is proving to be very beneficial. As a result of a number of these TCI and PDC bits available in reusable condition as a result of a large number of wells drilled every year in gas fields, significant cost savings have been achieved, which translates into millions of dollars in savings.
The rerun bits have substantial advantages over the new bits, primarily due to cost savings and enhanced bit designs with high durability and bit life over the last decade. For particular application in gas drilling, it is clear that having a large inventory of rerun bits available for almost all hole sizes will enable drilling cost optimization.
For many years, Saudi Aramco has searched for a way to replace the practice of drilling out the DV’s and Shoe Track with a tricone bit, followed by a polycrystalline diamond cutter (PDC) bit to drill the new formation to the next casing point. Many bit manufacturers have conducted trials to overcome the challenge, with limited success. This paper discusses a successful, single-run technology to drill out and continue drilling using only a PDC bit.
Investigations of the root causes of failure and erratic performance led to extensive review of bit design and drilling practices, but fail to overcome the single-run challenge posed by cutter wear and damage experienced during the drill out.
Recently developed shear cap technology provides a means of installing high-grade tungsten carbide caps on the PDC cutters. The caps protect the cutters during the drill out, and then wear away to expose the cutters in pristine condition for drilling the formation.
The shear cap technology has been tested extensively and optimized using various bottom-hole assemblies. The result has been a considerable breakthrough in the success rate for drilling the formation section, accompanied by a time reduction that has resulted in huge savings in offshore oil drilling operations.
The standard PDC bits fitted with the protective technology are successfully providing a one-trip capability, saving a round trip to change the bit and achieving a 100% success rate in drilling to the next the casing point. When drilling in the casing, the tungsten carbide shearing caps are effectively mitigating the cutter damage typically experienced when drilling out the shoe track. Drilling performance in the formation and the ability to efficiently drill the full section, demonstrates the undamaged condition of the cutters when the bit exits the casing. Overcoming the longstanding efficiency challenge of drilling both shoe track and formation in a single run is being achieved with the novel technology’s ability to enable optimal formation drilling by protecting cutters during the shoe drill out.
This paper presents an overview of the technical challenges in the design of floating offshore wind turbines (FOWTs) and the recent development of design guidelines for FOWTs. Extensive case studies, which evaluated the characteristic load conditions and global responses of FOWTs, are carried out to verify the design criteria. Three design concepts, including a Spar-type, a TLP-type, and a Semisubmersible-type floating wind turbine support structure and their associated stationkeeping systems, are selected for the case studies. Representative operational and extreme storm environmental conditions of the East, West and Gulf of Mexico coastal regions on the US Outer Continental Shelf (OCS) are considered. State-of-the-art simulation techniques are employed for the fully coupled aero-hydro-servo-elastic analysis of the integrated FOWT model. Relative importance of various design parameters as well as its impact on the development of design criteria are evaluated through parametric analyses. The paper is concluded with a brief introduction of the recently published ABS Guide for Building and Classing Floating Offshore Wind Turbine Installation.
A significant portion of offshore wind energy resources in the United States are available in water depths greater than 30 meters in the offshore regions near highly populated coastal states. At this and greater water depths, floating offshore wind turbines (FOWTs) could become more economical than bottom-founded designs.
Existing design concepts of floating support structures and stationkeeping systems for FOWTs are mostly developed based on experience from the offshore oil and gas industry, which has witnessed nearly 60 years of designing and operating floating offshore structures. There is a wealth of knowledge about hydrocarbon-related offshore structures installed on the US Outer Continental Shelf (OCS). What makes FOWTs unique, however, is the presence of wind turbines that follow a very different design approach. Strong interactions between the wind turbine, floating support structure and stationkeeping system also pose a great challenge to the design of FOWTs. Economic considerations for typically unmanned FOWTs further require leaner designs, serial production and mass deployment.
For these reasons, it is not technically sound or economically acceptable to transfer existing technologies of hydrocarbon-related offshore structures directly to FOWTs without further calibrations and necessary modifications. To address this, the Bureau of Safety and Environmental Enforcement (BSEE), U.S. Department of the Interior, awarded a research project to ABS in 2011 under its Technology Assessment and Research Program. The project was aimed at conducting a thorough review of existing technologies relevant to FOWT floating support structure and stationkeeping system designs and evaluating global load and response characteristics using the latest simulation methods. A draft design guideline for FOWT floating support structures and stationkeeping systems also was proposed based on the research findings of that project.
This paper presents a summary of the BSEE-funded research (Yu and Chen, 2012) as well as the subsequent development of the ABS Guide for Building and Classing Floating Offshore Wind Turbine Installation (ABS, 2013).
Seismic interferometry provides tools for redatuming physical data to a receiver or event location. Placing a virtual source close to a structure of interest yields many benefits for imaging. For example, it allows to mitigate the effect of velocity uncertainty in the overburden. Here, we consider the problem of estimating the Green''s function between two earthquakes located inside a subducted slab using earthquake data recorded at the surface. Our primary focus is to obtain an accurate time-image of a subducted interface. Known techniques, such as classical or source-receiver interferometry, are not directly applicable due to inadequate acquisition geometry. We propose a two-step kinematically correct redatuming procedure that first redatums the data from earthquakes below the subducted interface to the surface via classical interferometry, and then utilizes source-receiver wavefieled interferometry to redatum virtual surface seismic data to the location of a particular earthquake event.
The Hoop Fault complex in the Southwestern Barents Sea presents an imaging challenge to accurately model the sharp velocity contrast across a major fault boundary. Improperly accounting for this velocity discontinuity would lead a poorly focused image and false structures. We present an approach that leverages interpreted fault planes as well as marker horizons to drive and constrain tomographic velocity updates.
Exploiting information from multiple data sets can improve the quality of the estimated parameters and thereby the reliability of the resulting reservoir predictions. Combination of multiple data types can be done sequentially, where the model parameters are updated based on the information from one data type at the time; or simultaneously, where at each parameter update, the joint information from all available data types is taken into account. The latter approach has the prospect of stabilising the inversion by constraining the inversion with a higher degree of information. In this work, we present a method for structure-coupled joint inversion of controlled source electromagnetic (CSEM) data and seismic AVO data with application to production monitoring. By reformulating the unknown model parameters in terms of common structural relationships, we obtain a common model parameter that shares sensitivity to both data sets. The performance of the structurally coupled inversion is tested on synthetic examples where we compare the results of joint versus separate inversion of the data sets. We also investigate into the robustness of the joint inversion strategy with respect to a specific type of modelling errors.
We present a new data adaptive method for smoothing 3D post-stacked seismic attributes. This method reduces random noise while preserving structure without prior information of the structure orientation. Our method works by smoothing the data along a set of orientations defined within a neighborhood sub-window; the best result is then selected for output. The best orientation often approximates the true structure orientation embedded in the data; therefore, the embedded structure is preserved. The selection criterion for the “best” orientation depends on the data type and purpose of maneuver: it can be 1) minimum deviation, and 2) maximum or minimum or absolute-maximum summation. Our method can be further combined with median, alpha-trim, symmetric near neighbor, or edge-preserving filters. Based on preliminary results, our method effectively reduces random noise, eliminates footprints, and enhances coherence and curvature attributes. We also foresee its usage in processing of seismic data, such as to enhance auto-picking of horizons, first arrivals and refraction events.
In 2008, a marine field trial with a coil shooting design was acquired at Heidrun. In the preliminary processing of the data, some noise filters were used that assume straight line geometries and thus do not take the 3D nature of the data properly into account. Moreover, due to sparseness of data outside the 7 km
Goussev, Serguei (Fugro Gravity and Magnetic Services Inc.) | Yalamanchili, S.V. (Rao) (Fugro Gravity and Magnetic Services Inc.) | Hassan, Hassan (Fugro Gravity and Magnetic Services Inc.) | Davies, Marianne Rauch (NEOS GeoSolutions) | Smith, Paul A. (NEOS GeoSolutions)
In East Texas/North Louisiana Basin, the basinal sediments are often nearly flat-layered in their upper part and overly deep basement rocks. This geological structure creates a favorable subsurface environment for detection of residual gravity anomalies associated with elements of subsurface structure in the middle part of the sedimentary section. Within this depth range, a number of wells penetrated shales and reservoir quality sands and allowed the recognition of two types of stratigraphic plays. These plays are modeled as the “incised valley” and “lateral thinning-out” facies. Integration of the gravity, magnetic, seismic and well datasets made it possible to interpret the magnetic basement depth structure, dominant fault trends in the basement and sedimentary cover and identify the localized sedimentary mini-basins where reservoir sands accumulated. 2D gravity forward modeling demonstrated that such mini-basins could generate detectable gravity anomalies. Using seismic sections as a calibration tool, a “tuning” filter was designed to visualize the residual gravity anomalies generated by mini-basins with both types of stratigraphic plays. Application of this filter to the Bouguer gravity separates mini-basins'' residual anomalies from the gravity field components associated with the basement depth structure and delineates several areas of the most probable location of the recognized stratigraphic plays/facies.
Zhou, Bin (CNOOC Ltd-Tianjin) | Zhou, Joe (CGGVeritas Singapore) | Wang, Zhiliang (CNOOC Ltd-Tianjin) | Guo, Yonghe (CGGVeritas Singapore) | Xie, Yi (CGGVeritas Singapore) | Ye, Guoyang (CGGVeritas Singapore)
In the oil rich Bohai area, the Tanlu Fault zone plays an important role in hydrocarbon exploration and production. The strong velocity contrast across the high dipping fault structures, serious shallow water multiple problem and low signal noise ratio in the target zone prevent clear and accurate fault imaging from the conventional pre-stack time migration, previous attempt using Kirchhoff PSDM also failed to improve the image quality without first solving the low signal noise issues and creating accurate velocity model. In 2010, a complete reprocessing of the LD blocks using the most recent developments of the Pre-stack Depth Migration technology including the TTI (tiled transverse isotropy) model building and High Fidelity Controlled Beam Migration (HFCBM). Combined with the Shallow Water De-multiple (SWD) technology, the reprocessing provided a step change in the imaging quality in these areas, great improvement has been observed both in the structure images and signal noise ratio. TTI HFCBM should be considered as a viable tool to image the complex structure and decrease the exploration risk in this area.