Chee Khong

Surveillance in deep water wells is cost prohibitive. There is a need for significant hydrocarbon production or water shutoff incentive to justify the intervention in such wells. The wells straddle multiple stacks of soft sediment reservoirs, being completed with open hole gravel pack. While laterally extensive barriers between various sands units might help the water shutoff / containment, the gravel pack annulus still provides a conduit for water to move upwards and jeopardize the shutoff success. In this campaign a meltable alloy was deployed to plug the flow in both annulus and screens. In deep water subsea wells, water conformance control is often attempted blindly without flow diagnostic surveillance or production logs as a minimum. This can impact the production due to plugging substantial hydrocarbon production or inadequate flow from the remaining zones. Candidate wells or techniques for shut-off require robust diagnostics to improve the success rate and limit loss of oil or gas production. In a recent well work campaign production logs were acquired to optimize the water shut-off. Well access is challenged by limited rigup height (short lubricator) and well deviation. The well trajectory impacts the phase presence, mixing and recirculation. It requires a short array of sensors conveyed on tractor. Logging while tractoring capabilities in surface readout mode is required to minimize the rig time, improve depth control and perform real time data quality assurance. The multiple mini-spinners, electrical and optical probes are all positioned to the well's vertical axis to capture all local changes in the flow regimes. Sensor arrangement is sufficiently compact in this tool to minimize flow disturbance by tool occupancy and movement along the well. Real-time profiling of the complex flow regimes during the acquisition provided better log control and understanding of the downhole phase dynamics. Changing the mindset about subsea deep-water reservoir surveillance paid dividends in water shutoff operations, both for immediate decision make and for longer term well and reservoir performance management. There was a net benefit by deploying a compact axial array production logging string that allowed accurate rate and phase allocation and further identification of zones to be isolated using an innovative plug-back method that significantly reduced the water production.

Deepwater environments pose significant challenges in design and execution of comprehensive yet cost effective formation testing programs. For a recent deepwater appraisal well, pre-job modeling, advanced formation testing technologies, and in-situ fluid analysis were utilized to design and execute a formation testing program which provided significant improvement in the quality of data and fluid samples acquired, as well as significantly reduced time required for testing. Multiple PVT and bulk samples were collected with an advanced focused sampling probe, providing an average pumping time of 3.5 hours per sampling depth with sample contamination as low as 1%. This compared favorably to nearly 9 hours per sample depth, double the volume of fluid pumped, and fluid contaminations of 8-14% observed in the previous appraisal well using an unfocused probe. The low contamination improved the accuracy of real time Downhole Fluid Analysis (DFA) measurements such as density and viscosity, hydrocarbon composition and GOR performed with an advanced in-situ fluid analyzer. Fluorescence and reflectance detectors within the same tool were used to evaluate fluid phase state. Another important component of the acquisition were several Interval Pressure Transient Tests (IPTT) performed to evaluate horizontal and vertical permeability. An advanced 3D radial probe was selected over a conventional Dual Packer to perform these tests. The 3D radial probe was more time-efficient, provided better quality buildup data including vertical interference data (VIT), and presented lower operational risk. Real time measurement of fluid viscosity enabled the immediate estimation of permeability. Zonal permeability and permeability anisotropy (kv/kh) for the tested intervals were interpreted from the pressure transient responses of the radial probe and observation probe

Monobore completions have been installed in wells as far back as the 1980's. Early examples were reported in several SPE papers by companies such as Santos, Total and Unocal (now Chevron). The main drive being reduced drilling and completion costs. Perforating monobore completions is also not new and there are several methods to deploy guns into these types of well completions under various conditions (underbalance, overbalance or dynamic underbalance).Reservoir performance can be optimized through perforation modeling where analysis has shown that a tailored Dynamic Underbalance (DUB) approach can deliver productivity gains from 5% (shallow mud filtrate damage) to 40% (deeper mud filtrate damage) higher than traditional perforation techniques. This is a data driven optimization based on field data such as zonal permeability, pressure, temperature, fluid shrinkage factor, fluid viscosity, GOR, wellbore trajectory and completion design.To achieve maximum gain, multiple perforatin...

A vibrating rod downhole fluid density device with the unique perpendicular oscillation modes provides in-situ fluid density measurements that improve a wireline formation tester's pressure, mobility, downhole fluid analysis, and sampling applications. The measurement applications for the real-time water-base mud (WBM) formation-water sampling include contamination monitoring, in-situ fluid density, fluids identification, pressure gradient and fluid contact, and vertical compartmentalization. Field examples validate the measurements with the sample laboratory analysis and other measurements. Introduction Understanding the nature and composition of formation water is just as critical to the economics of field development as determining hydrocarbon composition. Chemical analysis of formation or connate water determines the scaling and corrosion potential of produced fluids, which determination is required for the design of completion and processing facilities. It also establishes the salinity for petrophysical evaluation, and fingerprints the aquifer for studies on basin hydrology. Water composition is important for production strategies involving inhibitor injection, wellstream mixing, process sharing, and enhanced oil recovery (EOR) injection (O'Keefe 2006; Godefroy et al. 2008). The formation water samples are required early in the exploration /appraisal phase because water will not be intentionally produced from conventional drill stem testing (DST) and will not be produced until the field cut water at the later stage, thus too late for the planning. In the offshore or in environmentally sensitive areas, where margins for error are small and large capital expenditures must be spent upfront, proper planning is crucial.

Surveillance in deep water wells is cost prohibitive. There is a need for significant hydrocarbon production or water shutoff incentive to justify the intervention in such wells. The wells straddle multiple stacks of soft sediment reservoirs, being completed with open hole gravel pack. While laterally extensive barriers between various sands units might help the water shutoff / containment, the gravel pack annulus still provides a conduit for water to move upwards and jeopardize the shutoff success. In this campaign a meltable alloy was deployed to plug the flow in both annulus and screens. In deep water subsea wells, water conformance control is often attempted blindly without flow diagnostic surveillance or production logs as a minimum. This can impact the production due to plugging substantial hydrocarbon production or inadequate flow from the remaining zones. Candidate wells or techniques for shut-off require robust diagnostics to improve the success rate and limit loss of oil o...

Abstract The China National Offshore Oil Corporation (CNOOC), Shell, and ConocoPhillips China, Inc.,(COPC) are partners in the development of the XJG oil fields in the South China Sea. The XJG fields are in a mature production phase and challenge COPC (the field ...

Abstract China National Offshore Oil Corporation (CNOOC), Chevron, and ENI, the field operator, are partners in the development of the HZ oil and gas fields, operating as the CACT Operators Group (CACT) in the South China Sea. The HZ fields are stacked, thin, ...

Abstract The China National Offshore Oil Corporation (CNOOC), Shell, and ConocoPhillips China, Inc.,(COPC) are partners in the development of the XJG oil fields in the South China Sea. The XJG fields are in a mature production phase and challenge COPC (the field ...

... Sheng, Cai Jun, Yang Hong Jun - CNOOC Zhanjiang Ltd Khong Chee Kin, Julian Zuo, Go Fujisawa, Andreas Hausot, Michael O'Keefe, Oliver C. Mullins ... For example, the Tahiti reservoir was shown by DFA to have an equilibrium distribution of asphaltenes [Betancourt et al 2007 ...