Proven Technologies and Solutions for Successful Production Enhancement in Malaysia with Array Production Logging

M field is a faulted anticline structure that lies in a deepwater turbidite environment. Field Development started in late 2016, with 10 oil producers and 2 water injectors. Within 2 years of production, significant GOR increase in some of the wells led to production curtailment, which has impacted the field production promise. Poor injectivity seen in one of the water injectors also led to an assumption of compartmentalization or sandface plugging/damage that required investigation. In order to evaluate intervention opportunities to mitigate against the high GORs and to determine the cause of the poor injectivity, production logging tools were proposed in four candidate wells. The objectives of the logging campaign were: To understand the gas influx profile into the well and how different compartments are contributing to the GOR Assess behaviour of G/O, O/O, O/W crossflows and their impact on reservoir depletion profile Aid decisions in requirements for downhole controls (i.e. AICD placement) vs surface controls Provide opportunity to couple PL logs with PNC logs to identify potential GOCs, estimate gas/water saturations and determine if there are any bypassed oils Based on the candidate wells, the following challenges were present: Highly-deviated/horizontal wells requiring complex conveyance solutions Multiphase flows (gas, oil and potentially water) in highly deviated conditions which further complicates fluid phase contribution calculations and velocity modeling Rig up height limitations on the platform which requires shorter logging tool strings High flowrates with tool lift limits requiring careful modelling work to ensure risks are understood and minimized In view of these challenges, a new Array Production Logging Tool (henceforth called New-APLT) was proposed as an alternative to the previous generation APLT. It has a more robust design with co-located sensors in a single module with additional optical sensors that improves flow measurement and gas detection. Additionally, screen tracers sampling was proposed in one well, which would help calibrate the tracer interpretations against actual fluid rates. The novel approach and synergistic efforts amongst many disciplines led to a successful execution of the logging campaign, and the first ever deployment of the New-APLT tool on e-line tractor. The timely results from the campaign which coincided with a 4D seismic acquisition has helped to justify downhole control options for some of the wells, and potentially helped to avoid costly remedial work on the water injector. The valuable dataset will also influence the infill development well campaign location, design and well count.

Seismic velocity modeling in the digital transformation era: a review of the role of machine learning

Seismic velocity modeling is a crucial step in seismic processing that enables the use of velocity information from both seismic and wells to map the depth and thickness of subsurface layers interpreted from seismic images. The velocity can be obtained in the form of normal moveout (NMO) velocity or by an inversion (optimization) process such as in full-waveform inversion (FWI). These methods have several limitations. These limitations include enormous time consumption in the case of NMO due to manual and heavy human involvement in the picking. As an optimization problem, it incurs high cost and suffers from nonlinearity issues. Researchers have proposed various machine learning (ML) techniques including unsupervised, supervised, and semi-supervised learning methods to model the velocity more efficiently. The focus of the studies is mostly to automate the NMO velocity picking, improve the convergence in FWI, and apply FWI using ML directly from the data. In the purview of the digital transformation roadmap of the petroleum industry, this paper presents a chronologic review of these studies, appraises the progress made so far, and concludes with a set of recommendations to overcome the prevailing challenges through the implementation of more advanced ML methodologies. We hope that this work will benefit experts, young professionals, and ML enthusiasts to help push forward their research efforts to achieving complete automation of the NMO velocity and further enhancing the performance of ML applications used in the FWI framework.

Interaction of extensional, contractional, and strike-slip elements at Mount Diablo and the surrounding eastern Coast Ranges, San Francisco Bay area, California: A model-based analysis

ABSTRACT This study presents three regional cross sections, a structural map analysis, and a schematic map restoration. The sections are constrained by surface geology and petroleum wells and were developed using model-based methods to be consistent with the regional tectonic context and balancing concepts. Together, these products depict the geometry and kinematics of the major fault systems. Insights from this research include the following. Franciscan complex blueschist-facies rocks in the Mount Diablo region were unroofed west of their current location and subsequently thrust beneath the Great Valley sequence in the mid-Eocene. East Bay structures are complicated by overprinting of Neogene compression and dextral strike-slip motion on a Paleogene graben system. Net lateral displacement between the Hayward fault and the Central Valley varies from 26 km toward 341° to 29 km toward 010° in the southern and northern East Bay Hills, respectively. Uplift above a wedge thrust generates the principal Neogene structural high, which extends from Vallejo through Mount Diablo to the Altamont Ridge. Anomalous structural relief at Mount Diablo is due to strike-parallel thrusting on the crest of a fault-propagation fold formed on the west-verging roof thrust. Uplift that exposes the Coast Range ophiolite in the East Bay Hills is formed by oblique thrusting generated by slip transfer at the northern termination of the Calaveras fault. The Paleogene extensional fault system likely extends farther west than previously documented. An east-dipping branch of that system may underlie the Walnut Creek Valley. Three-dimensional restoration should be applied to constrain geologic frameworks to be used for seismic velocity modeling.

Detection of magnetic tracers with Mx atomic magnetometer for application to blood velocimetry

In the new generation of blood velocimeter systems, considerable attention has been paid to atomic magnetometers due to their high resolution and high sensitivity for detection of magnetic tracers. Passing the magnetic tracers adjacent to the atomic magnetometer produces a spike-like signal, the shape of which depends on the position of the tracer, as well as its velocity and orientation. The present study aimed to evaluate the effect of abrupt variations in the instantaneous velocity of the magnetic tracer on the magnetometer response compare to constant velocity. Modeling the magnetic tracer as a dipole moment indicated that the velocity dependence of the magnetic field and local magnetic field gradient associated with moving magnetic tracer cause the spike-like signal to go out of symmetry in the case of variable velocity. Based on the experimental results, any instantaneous variation in tracer velocity leads to shrinkage in the signal width. The behavior has been studied for both magnetic microwire with variable instantaneous velocity and magnetic droplets in stenosis artery phantom. In addition, the position of the tracer could be detected by following the shrinkage behavior which may occur on the peak, valley, or both. These advantageous outcomes can be applied for high sensitivity diagnosis of arterial stenosis.

Ice thickness estimates of Lemon Creek Glacier, Alaska, from active-source seismic imaging

Lemon Creek Glacier, a temperate valley glacier in the Juneau Icefield of Southeast Alaska, is the site of long running (>60 years) glaciological studies. However, the most recent published estimates of its thickness and subglacial topography come from two ~50 years old sources that are not in agreement and do not account for the effects of years of negative mass balance. We collected a 1-km long active-source seismic line on the upper section of the glacier parallel and near to the centerline of the glacier, roughly straddling the equilibrium-line altitude. We used these data to perform joint reflection-refraction velocity modeling and reflection imaging of the glacier bed. We find that this upper section of Lemon Creek Glacier is as much as 150 m (~65%) thicker than previously suggested with a large overdeepening in an area previously believed to have a uniform thickness. Our results lead us to reinterpret the impact of basal motion on ice flow and have a significant impact on expectations of subglacial hydrology. We suggest that further efforts to develop a whole-glacier model of subglacial topography are necessary to support studies that require accurate models of ice thickness and subglacial topography.

Seismic Data Processing and Depth Imaging for Yingxionglin Complex Structures-Belt in Qaidam Basin, Tibetan Plateau

The Yingxionglin structural belt located in the world's highest-altitude petroliferous basin, Qaidam Basin. Due to its complex surface condition, subsurface structure and low signal-to-noise ratios (SNR) of seismic data, exploration and production is quite challenging. From 2012 to now, we continued developing and improving seismic data processing and interpretation workflow. After several rounds field support and testing, new techniques exploring and velocity modelling iteration, we gradually developed a suitable workflow for complex dipping structure imaging including signal processing, velocity modeling, and depth migration. The quality of final delivered 3D seismic data is significantly improved with the integrated static correction techniques, fidelity multi-domain noise attenuation, 5D MPFI regularization, integrated velocity modelling and final pre-stack depth migration. According to our final deliverables, we identified credible traps and high-production reservoirs were found.