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API RP 65-1-2018 pdf free download

API RP 65-1-2018 pdf free download.Cementing Shallow-water Flow Zones in Deepwater Wells.
This standard describes practices designed to prevent shallow-water flow (SWF) during and following the cementing of wells located in deepwater. It is the compilation of technology and practices developed and used by many operators around the world. Although most of the discussion in this standard is focused on SWF, shallow flows can be mixtures of water, gas, gas hydrates, and formation fines. There is no single method of preventing shallow-water flow, and many of the activities described may require customization to fit individual well conditions. While this standard is extensive, it is not meant to limit innovation and new technology. The content of this document is not all inclusive, and guidance from other sources may apply. Note that this standard is not meant to be a stand-alone training manual or well design standard. Although fairly comprehensive, there are still many details that are not discussed and that should be addressed when drilling and cementing wells in deepwater. It is meant to highlight key parameters for increasing the chance of successfully drilling and cementing casings where there is a risk of shallow- water flow and to discuss options that are available. More details can be gleaned from the references listed in the bibliography. Most of the information in this document is from U.S. Gulf of Mexico experience. The concepts can be applied in other deepwater environments with appropriate modifications. The user should consult experts within the industry for specific details of the cementing process relating to the technology being used by a specific company for a specific scenario. The construction of the casings through the SWF zones should be a team effort to be successful. All parties involved shall participate in the planning and execution of all phases of the process to ensure successful construction of the conductor and surface casings. In this standard, where practical, U.S. customary units (USC) are included in parentheses for information.
Flows from these shallow formations are typically a result of abnormally high pore pressure in under- compacted and usually unconsolidated sediments formed in a rapid depositional environment. Not all flows are the result of these naturally developed formation geopressures. Other causes for abnormal shallow pressures include hydraulic communication from deeper, higher-pressure formations, tectonic uplift, and induced storage during drilling, casing, and cementing operations. Flow of sediments results in hole enlargement, which can increase the rate of flow and make it more difficult to control. The enlargement may also cause caving of formations above the flow interval. The flow of water and formation material from these zones can result in damage to the wells, including foundation failure, formation compaction, damaged casing (wear and buckling), re-entry and control problems, sea floor craters, mounds, and crevasses (R.M. Ostermeier et al. 2000, Eaton, L.F. 1 999). Flow channels through or around the cement sheath may be formed as a result of one or more of the following: — poorly designed or executed primary cementing; — flow occurring due to dilution or channeling while the cement is being placed; — flow occurring after the cement slurry is placed, but before it has attained a structure sufficient to prevent formation fluid flow, will create channels through which flow can continue; — poor hole conditions. Geopressure can be transmitted through channels in the cement sheath and, if trapped by a seal (mechanical isolation), can charge or fracture a formation of lower pressure or strength. If the fracture extends beyond the wellbore, it could eventually reach the surface, breaching at the seafloor around the well. Fractures can also extend to neighboring wells and create a flow path to the seafloor if those wells are not properly cemented.
1.5 Challenges for Controlling SWF The following factors make drilling and cementing sections with SWF potential challenging: a) b) Temperatures at the mudline are low, usually in the range of 1 .5 °C to 1 3 °C (35 °F to 55 °F). The geothermal gradients found in deepwater areas may be sequestered as a result of the water-depth effect and may suppress wellbore temperatures throughout the entire stratigraphic column. In other areas, the geothermal gradient may recover quickly with depth. The low temperatures result in slow hydration of the cement, often making special slurries or additives, or both, necessary. Pore and fracturing pressures are close due to the depositional environment, making the drilling and cementing pressure margins narrow.

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