Sand production is a common problem throughout the oil and gas industry, particularly in ‘high rate’ gas reservoirs coupled with low rock compressive strength. Conventional downhole sand control techniques such as gravel packing can act to limit both well geometry and/or productivity. Furthermore, problems with gravel pack installations can lead to preferential inflow, leading to ‘hot spotting’ and ultimately loss of sand control. To evaluate the erosion resistance of sand control equipment under the highly erosive environment of high rate gas wells, innovative testing equipment is needed. This paper will discuss the development of a Gas Sand Screen Erosion Test (GSET) rig and its application to evaluate the erosion resistance of ceramic sand screens. GSET is designed to simulate ‘accelerated’ erosive down-hole conditions. The GSET cell can accommodate but not limited to a screen stub section, screen coupons and variety of downhole equipment. A combination of high flow rate gas and volume controlled particle reservoir matched sand is coalesced into an acceleration tube. The high velocity sand particles (>80m·s-1) impact the ceramic sand screen, causing erosion within the target area. In this paper, the GSET rig was operated for 48 hours at maximum velocity (>80m·s-1) and with a sand concentration of 750 ppmw. Take into consideration that the velocities seen throughout this paper are significantly greater than what a conventional reservoir/completion system would have to tolerate. Initial and final sand screen analysis was conducted to evaluate the performance of erosion resistance. An array of analysis techniques was applied with focus on gap aperture size and surface topography. Gap aperture measurements were a focal point, as it is directly proportional to its ability to maintain sand retention capabilities. This paper highlights the potential of the new GSET rig, enabling laboratory testing of erosion resistance of sand control equipment for high rate gas wells under accelerated conditions. Test results obtained with the ceramic sand screen section underpin the inherent high erosion resistance of ceramic sand screen technology ensuring longevity in highly erosive environments. Thus, providing opportunities to complete both new reservoirs and intervene in existing fields with remedial sand control solutions; through extension of the viability of stand-alone screens, simplification of well construction or intervention and increase in productivity. The observations made by the authors are supported by extensive laboratory testing. The resources provided in this paper will allow petroleum engineers to appropriately evaluate the potential benefits of utilizing ceramic sand screen technology in their completions.

As part of the overall Ichthys project there was a requirement to develop a remedial sand control application that would be suitable for installation should the sand production levels exceed the tolerance of the system. After an exhaustive review of available techniques, a remedial insert ceramic sand screen was selected as a potential option for these high rate gas wells. In order to be confident that the screen would be suitable for the application a comprehensive design and qualification plan was developed. Due to the nature of the application and the technology itself the qualification programme was significantly more complex than typical oilfield equipment qualification; many of which can adopt standard API/ISO testing protocols with clear cut pass/fail criteria. A number of specific elements were required to underpin the qualification. Firstly and perhaps most importantly was pre-qualification of the overall strategy itself. This can be thought of as the engineering work to endorse the approach, including the assessment of any inherent risks, and the development of the overarching qualification framework including understanding the dependencies between specific qualification work scopes. Once the strategy was endorsed and the framework developed, a significant amount of time was spent maturing the testing programme and the subsequent pass/fail criteria, often involving extensive discussion with a number of specialised companies and especially the provider of the screen. A thorough and extensive set of modelling and testing was conducted to endorse the final product for the application including fundamental FEA and CFD modelling through more traditional burst/collapse testing, end ring weld certification and corrosion studies to bespoke bending, impact and erosion testing. In addition as this is a new technology and does not conform to any existing sand screen quality plan it was necessary to conduct a joint quality management system audit and screen manufacturing assessment. This led to the construction of an agreed Quality Control Plan; and specific production quality checks to ensure critical requirement conformance of the overall process and end product. The end result was a successfully qualified product for the Ichthys high rate gas remedial application.

Managing sand production is becoming an increasingly important issue for petroleum production wells, particularly in challenging environments such as deep water, or gas fields with high flow rate production where sand tolerance is very low and changing the completion strategy could be costly. Sand production prediction is an integral part of overall field development planning. Consequently, it is important that the risk of sanding is accurately evaluated and appropriate measures are taken for well completion. The critical part in a sanding study is to define a proper rock deformation threshold based on laboratory tests or field observations. Due to the lack of sufficient field sanding data or for the sake of modelling simplicity, the rock deformation threshold is frequently defined either inappropriately or too simplistically because of the failure to recognize the intrinsic heterogeneities of reservoir rocks. In this paper, two cases are presented with the deformation threshold "critical plastic strain limit" defined by a numerical simulation approach. One case represents a weak to medium-strength sandstone reservoir and the other a stronger, clean sandstone reservoir. In both cases, a comprehensive core testing dataset and a field-validated geomechanical model are available. In the weak-medium strength case, there were also several years of production history with sanding observations available from a few wells. The numerical method uses an elasto-plastic material model where the rock behaviour is numerically defined from systematic triaxial compressive core tests and a rock failure criterion based on the plastic strain limits modelled from Advanced Thick-Walled Cylinder (ATWC) core tests with calibration against field sanding observations. From the modelling of a range of high-quality ATWC tests and field sand production experiences, strong correlations are found between the critical strain limit and the rock compressive strength for both cases indicating different critical strain limit thresholds for different rock strengths and rock types. Although high-porosity and weaker rocks may still have a higher risk of sand production than low-porosity and stronger rocks, the risk of sanding may not be as high as predicted if a single threshold is used for the entire rock strength and porosity range. The use of a single threshold for the whole field could over- or under- estimate the risk of sand production, especially for reservoirs with a moderate risk of sand production. Sanding evaluations of the two cases revealed that the predicted sanding risk is potentially misleading if a simple sanding threshold is defined without adequately capturing the heterogeneity in reservoir rocks. This approach may prohibit the selection of an appropriate completion strategy for the entire field. This paper is concluded by presenting a rock testing program procedure for sanding evaluation studies to better capture the heterogeneity in reservoir rocks and, hence, to predict the sanding risk more reliably.

Canine and feline hookworms are important causes of skin infections in humans including creeping eruption or cutaneous larva migrans. Further, Ancylostoma caninum has been shown to cause intestinal infections in humans resulting in eosinophilic enteritis. To determine the prevalence of Ancylostoma species in dogs and possible intestinal exposure of humans in Jamaica, stool samples from both species were screened using PCR targeting the internal transcribed spacer (ITS-1), 5,8S and ITS-2 region of the ribosomal DNA genes. The prevalence of hookworm infections in dogs based on PCR was 60.9% (78/128). DNA sequencing revealed that A. caninum accounted for 88.2% (30/34) and A. braziliense for 11.8% (4/34) of infections in dogs. Further, DNA of A. caninum targeting the same gene fragment was identified in 22.1% (17/77) of stool samples from patients presenting at hospital with the gastrointestinal symptoms. This report of molecular identification of A. caninum DNA in human stools provide further support that intestinal infection with this parasite may be underreported in endemic areas.

As subsea completion and tie-back development plans become more plentiful, the impact of sand failure on production often severely impacts the economics of a gas field. The integrity of downhole, subsea and facility equipment may be compromised due to excessive sand production which can potentially lead to catastrophic failure. In cased and perforated sand-face completions, good cement sheath coverage across the casing can act as the main defense against excessive sand production. An integrated approach involving cement design, execution and subsequent evaluation is therefore critical to minimise sand production during the life of the well. In this paper, we outline the evolution of the process of cement design, placement and evaluation used in a multi-well development campaign by an operator to achieve quality cement placement across the entire well length of the sub-horizontal wells. At the commencement of the drilling campaign, perforation intervals were initially limited due to the combination of high levels of sanding risk and interpreted cement log. To limit unperforated sections, a dual pronged approach was instigated looking at both cement design and operations, and cement bond log evaluation. As the campaign progressed, both elements were improved leading to an overall improvement with respect to perforation length. Challenges overcome included lost circulation in fractured formation, poor mud removal in extended horizontal casing, gas migration into the cement sheath, the presence of micro annuli by the loss of acoustic coupling due to oil-wet casing and test pressure applied between cementing operations and evaluation. In this paper, the entire cementing program design, placement and evaluation workflow will be explained with specific examples from the field development. Special focus will be given to the evaluation of the cement using state-of-the-art high-resolution wireline technology leading to a reduction in interpretation uncertainty through advanced workflows. Finally, examples will be provided where the inputs from the logs were integrated with both drilling and petrophysical data to evaluate the sanding propensity, thus allowing the operator to confidently perforate high-risk zones and ultimately improving well productivity.