Sand control has traditionally been one of the biggest problems affecting production facilities and the design of surface equipment leading to escalation of project costs. With industry venturing into deeper waters and rising crude prices it's essential to develop complete and forget techniques for offshore locations most probable to produce sand. Hence a proper analysis for sand prediction and management has been at the forefront in research by many companies. The most viable alternative today being gravel packs although requiring constant attention as seen through various literature reviews. We emphasized on the chemical consolidation technique for sand control which has been overlooked but is promising considering escalating maintenance costs. We would like to introduce a new resin consolidation system which is cost effective and withstand very high pressures and temperature ranges from 50 oF to 450 oF. The resin consists of Aromatic Polyesteramide and Tri-alkoxy organo silane based consolidation system. The chemicals combine together on contact with formation water to essentially hydrolyze it at the sites to form a strong silanol adhesive which bonds the grains together thus giving a highly strong bond. The highlight of the paper is the process of consolidation which is site specific thus preventing the considerable loss in porosity and permeability as is generally seen in chemical consolidation systems. The paper describes the complete properties of the polymer resin system and the process of consolidation with the new system. In addition it describes the advantages of being environmental friendly and easier to handle with comparison to certain furan based resin systems that are currently used in the industry and have handling issues. Introduction Sand production is defined as production of fines leading to plugging of perforations of the well or sand, fines being produced along with hydrocarbons leading to decrease in production efficiency. Sand problems are usually associated with shallow reservoirs which are unconsolidated due to lack of cementation material and overburden pressure. But literature review has suggested that sand production problems have been encountered in deepwater basins due to various factors which include high production rates. There may be multiple factors leading to sand production but essentially they all lead to reduction in production efficiency and also damage to equipment thus leading to economic losses. Hence it is absolutely essential to design run and forget system that prevents sand production.
The majority of enhanced oil recovery projects currently underway are based on Water floods which are known to provide lesser recovery compared to other recovery mechanisms. Many such reservoirs exist where the recovery has been less than 30% altogether due to various drawbacks of the conventional Water floods. The paper would like to discuss a new EOR technique using Acoustic and Seismic energy to reduce interfacial tension and promote coalescence of oil ganglia using the resonant frequency principle. The technique uses pressure and sound waves at pre-determined frequencies to set the oil molecules in motion to promote coalescence and thus reducing the fingering effects. The flood pattern can be optimized by recovering oil from previously unswept areas. It thus enhances the life of the primary flood providing valuable economic savings. The process can also be applied to various reservoirs in their tertiary recovery phase to extend the life of the project. Experiments conducted in the lab show that the frequency of oil and water may differ from reservoir to reservoir and compositional analysis of samples is required to determine the resonating frequency. The design of the downhole tools for injector wells to implement this technique are also discussed briefly. Introduction The Oil production is on decline with all major producing reservoirs already reaching their peak period, thus emphasizing the need of enhanced oil recovery techniques to produce oil left in the reservoir after waterflood and other pressure maintenance techniques. According U.S. Department of Energy, more than 60 % of the oil is left in the reservoirs which are currently the target for EOR. Various methods have been proposed and many have been implemented in fields around the globe. They include chemical, thermal, microbial and many others. They all aim to reduce the residual oil saturation in the reservoirs to increase Expected Ultimate Recovery (EUR) and Recovery Factor. Seismic stimulation is also one of the techniques which follow the underlying principle of reduction of residual oil saturation. The interest in Seismic or Vibrational stimulation is a few decades old, primarily with research projects being carried out in the 50's in the United States and Russia where effect of earthquakes and Human induced shocks on oil production was studied and various reports were published postulating the underlying principle for the process.
Certain abandonment operations require plugs to be set off-bottom in a well. The challenge in setting plugs in highly deviated wellbores lies in obtaining a competent hydraulic seal that can qualify as a barrier to any potential flow zones. Failure to achieve a good cement plug leads to increased nonproductive time (NPT) from cleanout, drillout, and setting additional plugs. Small slurry volumes, unstable fluid interfaces with respect to gravitational forces, and fluid contamination add to the complications. In the Caspian Sea abandonment operations, plug-placement simulation aided in designing cement plugs and setting procedures in inhibited seawater, water-base, or oil-base drilling fluid environments. The advanced cement plug placement simulator was used to design fluid properties and optimize volumes for plug-placement operations in highly deviated Caspian Sea wells.For successful placement, physical fluid properties and fluid mechanics were used in the advanced placement simulator; in addition to the fluid behavior, the simulation took into account well geometries, tubular dimensions, and mechanical separation devices. Various parameters affecting successful plug placement, including but not limited to, length of tailpipe, gel strengths, underdisplacement volumes, and placement procedures were input into the simulations. Balanced cement plug placement is widely practiced by many operators. In the literature, it has been shown that when smaller diameter tubing or tailpipe is run on the bottom of drillpipe, the assumption that all fluids both inside and outside the drillpipe will remain in hydrostatic equilibrium is wrong. In this study, advanced placement modeling illustrated that an initially balanced cement plug may become unbalanced while pulling a cement string with tailpipe out of the hole. Multiple abandonment operations performed in Caspian Sea wells provided key lessons for wellbore preparation, fluid design, and wellsite execution. Design decisions made from the simulation results and improvements made with implementation of industry best practices increased the ability to get plug placement right every time from the first attempt.
Mud Gas Isotope Logging (MGIL) is a gas fingerprinting technique that uses isotopic analyses of mud stream. The primary purpose of MGIL is to assess the extent of a reservoir and identify communication with any other formations. A Gas chromatograph is the main component used in MGIL. Although analysis using a GC will give amounts of methane, ethane, propane (paraffins); napthenes and aromatics are not explicitly analyzed. Also it is very difficult to distinguish between wet gas, condensate and oil using present day GC instrumentation. Another critical element is the speed at which readings can be taken with typical GC cycles of 3-6 minutes which may lead to thin zones not being traced at high ROP. It is not possible with GC based methods to distinguish compounds that exist as a free phase in the pore system from those that may be dissolved in an aqueous pore fluid since GC does not measure a wide range of Carbon species. This paper proposes the use of Mass Spectrometry to analyze mud samples at wellsite. Samples can be analyzed to produce mass spectra of mass to charge ratio {MCR} across a range encompassing both abundant and trace inorganic and organic elements. MS holds a upper hand on GC because the latter does not provide chemical information, is comparatively slower compared to MS which gives real time results; and does not have baseline sensitivity to analyze fluid inclusions. MS also allows tracing of minute fractions of elements since MCR is unique for every element and compound. A further aspect of the paper is to create a chemical log which is a combination of species detected in the gas sample and species extracted from the mud system. Accordingly the chemical log can be used to influence drilling testing and well completion decisions. Some other applications of MGIL-MS include distinguishing between thermogenic & biogenic gas, monitoring H 2 S concentrations, identifying original fluid contact and CO 2 flood breakthrough detection.
The drive to recover hydrocarbons from difficult to reach reservoirs and optimize production is taking center stage in the Exploration and Production industry. Complex wells are being planned which push the existing technology to limits. The success and longevity of such wells depends upon providing good zonal isolation and sound well integrity for the complete life cycle of the projects. Cementing the wells in a narrow pressure regime without losses and overcoming challenges for optimum zonal isolation presents a unique test to the industry. The Extended-Reach-Drilling (ERD) wells drilled in the Caspian Sea prior to 2011 have historically seen inadequate zonal isolation in the long intermediate section due to channeling of cement during placement; consistent with directional profile of the wells. Remedial cementing was needed in some cases before the next phase of the well. As the acceptance criteria for well integrity becomes more stringent, the onus lies on achieving zonal isolation during primary cementing through a combination of optimized cement placement and mechanical barriers. This paper presents the investigative approach towards earlier jobs and the recommended suggestions which led to improvement that was confirmed by cement evaluation logs. The authors present case histories with lessons learnt during the course of implementing the new approach to cementing design and the success of achieving adequate cement coverage across potential flow zones.
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