Loss circulation is the biggest challenge after drilling and weather-related problems during the process of constructing new wellbores. As per industry figures, more than USD 2 billion per year are spent in combating losses. In the Kohat-Potwar plateau of the Upper Indus basin of northern Pakistan, a harsh and complex environment, a well usually takes anywhere from 180 to 270 days to drill. The overall time taken to drill depends on the formation thicknesses, severity of the losses, and the concession location within northern Pakistan. High-pressure water zones are located close to salt and shale formations, above the potential reservoirs. While drilling through the high-pressure formations, high mud weights greater than 1980 kg/m3 (16.5 lbm/gal) are required to maintain a well under control, which often leads to induced losses during drilling and also while running casing. The mud weight is typically lowered to 1500 kg/m3 (12.5 lbm/gal) or lighter to combat massive losses in naturally fractured limestone formations in the production hole. Engineered fiber-based loss circulation (EFBLC) control pills, based on a specially engineered fiber system and the particle size distribution principle, were developed to control the losses. The pills were effective in curing losses during drilling and while cementing; prior to the introduction of the EFBLC pills, operators spent days in combating losses with numerous traditional methods. Also, the pills were robust enough to work in water-base mud (WBM), oil-base mud (OBM), or synthetic-base mud (SBM) environments with weights up to 2040 kg/m3 (17.0 lbm/gal). In applications in northern Pakistan, the EFBLC pills were successful in combating the losses while drilling and cementing, thus reducing the threat of nonproductive time (NPT);minimizing the quality, health, safety and environmental (QHSE) concerns of well control; and preventing costly remedial jobs due to poor zonal isolation.
The operational and technical complexity of cementing operations has increased with deepwater exploration entering frontier regions on a global scale. An efficient knowledge management system (KMS) plays a vital role in providing a flow of information, and it helps in applying the findings of one area and to another area. This paper elaborates how a major service company has increased the service quality of deepwater cementing operations by using a KMS.All the knowledge, information, and experience from a cementing operation can be uploaded by field personnel in the form of lessons learned best practices, case studies, and more. Each knowledge-content related to deepwater cementing is reviewed by a dedicated team of subject matter experts (SMEs). After the content is validated by the SME, it can be accessed by the employees in diverse locations to improve their local operations. The information is maintained in the system until it is obsolete, which allows effective knowledge sharing even after the experienced employees have moved on to other assignments or are geographically far from the operating location. Different engineers working around the clock update the KMS and provide support to the field and operational staff.A key advantage of the KMS is that it promotes continuous improvement and standardization of the deepwater operation methodologies, including processes, reports, documentation, and more. The KMS also provides interactive training material such as deepwater cementing manuals, descriptions of special cement systems, and guides for troubleshooting the cement unit. The software application that runs the KMS is intuitive, and easy to use. The paper uses case study to highlight how the KMS has helped in planning for the technical and operational complexity of deepwater cementing operations in different regions around the globe.
Cement evaluation is a critical part of a cementing operation. Recent industry events and the continuous tightening of regulations for cement placement have elevated the importance of cement evaluation to heights greater than ever. The initial verification of a primary cement job is performed using the pressure trend obtained while pumping, because the pressure increases as the cement rises in the annulus. The actual pressure trend can then be compared with the expected pressure to infer the actual cement height in the annulus; however, this methodology can only predict but not confirm the top of cement (TOC). In deepwater, the regulatory agencies may require physical evaluation of TOC in specific strings of the well that can require running cement bond log (CBL) tools for those strings. This would use the critical path time for every CBL run. In addition, this regulatory agency requirement can also be technically challenging because cement bond evaluation for casing as large as 18-in. that is placed in a 22-in. open hole is the upper threshold limit for conventional wireline conveyed CBL tools. Many operators are now runing logging-while-drilling (LWD) sonic tools for open hole compressional data. Using the same sonic tools, logging can be performed through the casing strings on the same run and the results can be analyzed to confirm the TOC. The data presented here seems to show that the results agreed well with the predicted TOC from the pumping data. The use of this tool for cement evaluation was further validated against CBL evaluation that was performed on deeper strings in example deepwater exploration wells. The paper will elaborate on how the integration of this technology can provide precise TOC evaluation and save the operators considerable rig time per section.
The oil and gas industry involves various high-risk operations. In conventional oil and gas operations, pressure pumping is performed during the complete life cycle of the well. Normally, a cement-pump unit (CPU) is used to perform services such as cementing, blowout preventer (BOP) testing, formation integrity tests, and more. Operating a conventional cement unit requires the cement-unit operator to be directly over pumps and treating lines that contain pressurized fluid. During pumping operations, especially BOP testing, the pressures can get as high as 15,000 psi. Any leak or rupture in the lines at this pressure presents hazardous situation in the cement room. As per the hazard-analysis risk-control (HARC) analysis, two factors are required to have an incident. One is "likelihood" and the other is "severity" of that risk. At present, the majority of the current industry preventive measures aim at reducing the likelihood of a risk. The remote-controlled cement-pump unit (RCCPU) sets a new benchmark in safety standards by removing the likelihood factor, thus eliminating the risks pertaining to pressure pumping. With this engineered innovation, the pump unit is in a safe room, and the cementer is in a separate control room with advanced computer systems to operate the unit. This unit isolates the cementer from risks such as pressure, noise, height, adverse climate, and more. The automated control of the unit and the cement mixing system helps in achieving a high service quality (SQ). The innovative systems and the advanced engineering that the RCCPU uses to isolate the risks from the personnel change the paradigms of pressure pumping. While the current technology still requires the RCCPU operator to be onboard the vessel, however, work is in progress to operate the RCCPU from onshore facility.
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