Essam, Wael (BP) | Scarborough, Christopher (BP) | Wilson, Nick (BP) | Shimi, Ahmed (BP) | Santos, Helio (Safekick) | Hannam, Jason (Safekick) | Catak, Erdem (Safekick) | Lancaster, Jay (Seadrill) | Gooding, Neil (Seadrill) | Baan, Robert (Seadrill)
BP had long recognized the benefits of MPD, having been using it for years to deliver very challenging wells in Egypt, Trinidad and the North Sea; and it was time to bring these benefits to its GoM operations. Once the company team identified a portfolio of suitable candidate wells to allow the economics of the application to be advantageous, they partnered with Seadrill to provide the MPD service integrated into the West Capricorn drilling rig. This approach builds on synergies within the drilling contractor organization to achieve long term economic, competency, and risk management benefits, resulting from integrating this drilling method on the rig, and eliminating interfaces with 3rd party providers. The paper will discuss how the company and the drilling contractor teams, together with equipment suppliers and training providers, managed the project from initial system design, to installation and commissioning, to the successful delivery of the first well using MPD, at top quartile performance. It will discuss the process for optimizing the design and testing it from a reliability and process safety perspectives; engaging the regulatory authority and the classification society; integrating MPD in the well planning process and developing operational procedures for use on the rig; and delivering a training program for the wider team covering the technical and the human factors aspects to ensure a successful delivery.
Hadiaman, Farid (BP) | Mollayev, Samir (BP) | Huseynzade, Nijat (BP) | Valiyev, Ziya (BP) | Gracia, Jesse (BP) | Galvan Amaya, Jeanine (BP) | Fulks, Jeff (BiSN) | Rahimov, Khalid (Baker Hughes GE) | Pinero, Luis (Baker Hughes GE) | Ruzmetova, Sitora (Baker Hughes GE)
Thru-tubing uphole re-completion is a workover technique aiming to re-complete the existing wellbore by abandoning the lower producing zone and subsequently perforate upper layer. There are various techniques used to abandon the lower zone worldwide. Specific to Caspian Sea development, the abandonment will only be required to set an isolation plug. However, statistically speaking, success ratio of lower zone abandonment, is quite low using current plugs set in different condition of completion. In addition, the risk of deploying balance cement plug also presents significant challenge due to interval limitation between top of the cement and new perforation interval. It is deemed necessary to find a fit-for purpose solution that provides a solution to the Caspian Sea environment plug and abandonment strategy. A new plug technology, metal to metal system, was introduced to provide assurance isolating the lower zone prior to perforating new upper zone. Subsequently, a wireline deployed or pipe (tubing) conveyed perforation is not an attractive solution to thru-tubing up-hole recompletion technique. A new technology to perforate lively is selected from safety and economic point of view for this specific well. The perforation was done in underbalance condition with intelligent coiled tubing. The uphole re-completion (well delivery) performance was more attractive than other conventional uphole re-completion techniques. This paper will elaborate the success of recompletion techniques by deploying multiple new technologies in the Caspian Sea.
Tavassoli, Shayan (The University of Texas at Austin) | Shafiei, Mohammadreza (The University of Texas at Austin) | Minnig, Christian (swisstopo) | Gisiger, Jocelyn (Solexperts) | Rösli, Ursula (Solexperts) | Patterson, James (ETHZ) | Theurillat, Thierry (swisstopo) | Mejia, Lucas (The University of Texas at Austin) | Goodman, Harvey (Chevron ETC) | Espie, Tony (BP) | Balhoff, Matthew (The University of Texas at Austin)
Wellbore integrity is a critical subject in oil and gas production, and CO2 storage. Successful subsurface deposition of various fluids, such as CO2, depends on the integrity of the storage site. In a storage site, injection wells and pre-existing wells might leak due to over-pressurization, mechanical/chemical degradation, and/or a poor cement job, thus reducing the sealing capacity of the site. Wells that leak due to microannuli or cement fractures on the order of microns are difficult to seal with typical workover techniques. We tested a novel polymer gelant, originally developed for near borehole isolation, in a pilot experiment at Mont Terri, Switzerland to evaluate its performance in the aforementioned scenario.
The polymer gel sealant was injected to seal a leaky wellbore drilled in the Opalinus Clay as a pilot test. The success of the pH-triggered polymer gel (sealant) in sealing cement fractures was previously demonstrated in laboratory coreflood experiments (
The novel sealant was successfully deployed to seal the small aperture pathways of the borehole at the pilot test. We conducted performance tests using formation brine and CO2 gas to put differential pressure on the polymer gel seal. Pressure and flow rate at the specific interval were monitored during and after injection of brine and CO2. Results of performance tests after polymer injection were compared against those in the absence of the sealant.
Several short-term (4 min) constant-pressure tests at different pressure levels were performed using formation brine, and no significant injection flow rate (rates were below 0.3 ml/min) was observed. The result shows more than a ten-fold drop in the injection rate compared to the case without the sealant. The polymer gel showed compressible behavior at the beginning of the short-term performance tests. Our long-term (1-week) test shows even less injectivity (~0.15 ml/min) after polymer gelation. The CO2 performance test shows only 3 bar pressure dissipation overnight after injection compared to abrupt loss of CO2 pressure in the absence of polymer gel. Sealant shows good performance even in the presence of CO2 gas with high diffusivity and acidity.
Pilot test of our novel sealant proves its competency to mitigate wellbore leakage through fractured cement or debonded microannuli, where other remedy techniques are seldom effective. The effectiveness of the sealing process was successfully tested in the high-alkaline wellbore environment of formation brine in contact with cement. The results to date are encouraging and will be further analyzed once over-coring of the wellbore containing the cemented annulus occurs. The results are useful to understand the complexities of cement/wellbore interface and adjust the sealant/process to sustain the dynamic geochemical environment of the wellbore.
Altemeemi, Bashayer (KOC) | Gonzalez, Fabio (BP) | Al-Nasheet, Anwar (KOC) | Gonzalez, Doris (BP) | Al-Shammari, Asrar (KOC) | Sinha, Satyendra (KOC) | Muhammad, Yaser (Schlumberger) | Datta, Kalyan (KOC) | Al-Mahmeed, Fatma (KOC)
Sound development plans are based on complex 3-D 3-Phase multimillion grid reservoir simulation models. These models are used to run different scenarios where probability distributions are included to understand the impact of uncertainties and mitigate main risks that could raise during the life of the field. With today's available dominant supercomputers, reservoir engineers have the tendency to undervalue the power of classical reservoir engineering. However, in a fully connected reservoir tank that honors the basis of the material balance equation, material balance technique has been long recognized as a powerful tool for interpreting and predicting reservoir performance by estimating initial hydrocarbon in place and ultimate hydrocarbon recovery under various depletion scenarios. In brief, under the right conditions, material balance technique is a suitable tool for field development planning. The power of material balance to predict long term performance is undisputable, especially in the case of a prevailing uncertainty. This is the case of the Magwa-Marrat field, where the development plan has historically been driven by the potential risk of asphaltene deposition in the reservoir.
The objective of this paper is to show a step by step process to integrate data to build a reliable model using material balance and how this model is utilized to progress a field development plan capable of managing uncertainty and provide the tools to mitigate risk.
Pressure data is obtained from repeat formation tester (RFT), static data from shut-in pressures and reservoir superposition pressures from pressure transient analysis. The average reservoir fluids properties are retrieved from a compositional equation of state based on circa 20 PVT studies.
The material balance model was successfully completed, and the resulting stock tank oil initially in place (STOOP) was compared to volumetric calculations. Solution gas, rock compaction and aquifer influx were determined as drive mechanisms. The Campbell Plot, diagnostic tool, was proven to be prevailing defining early energy to determine STOOIP and the aquifer properties were calculated by matching the distal energy
The material balance model was then used to run different development strategies. This methodology captured the impact of depleting the reservoir down to Asphaltene Onset Pressure (AOP) as well as below AOP. The model was also used to define the requirements for water injection rates and startup of a water flooding project for pressure support. Additionally, the material balance work was implemented to support reservoir management and to maximize recovery factor.
This paper presents an innovative approach of integrating asphaltene behavior from laboratory tests and fluid studies, combined with material balance to screen development scenarios for an efficient depletion plan including water injection to manage asphaltene risks and optimize ultimate recovery. Finally, a fully ground-breaking strategy, not reported earlier to the knowledge of the authors, has been established to manage the perceived main risk in the Magwa-Marrat reservoir.
The advantages of measuring gravity in the borehole environment have been well established in the literature and through first-generation instruments. These measurements can be very effective for directly imaging mass distributions at-depth in the subsurface and at large-distances from well bores. To date, a breakthrough has been limited by the sensor form factor (size) and measurement stabilization. Newly emerging MEMS three-axis microgravity technology, deployable by wireline, is showing the potential for a host of applications and capable of realizing the long-coveted advantages. For reservoir surveillance, a primary application is to perform more pro-active, frequent flood front monitoring. With its large volume of investigation, the proposed three-axis borehole gravity measurements would complement as well as fill the existing gap between traditional methods such as Pulsed Neutron and 4D seismic. Further applications extend to saturation monitoring, by-passed pay, and thin-bed identification.
In conjunction with a collaborative program to develop a three-axis gravity sensor that is now being incorporated into a 54-mm diameter wireline tool with a targeted sensitivity ≈5 μGal (microGal), we have carried out extensive numerical studies to understand the signal strengths in such measurements produced by the dynamic processes in different types of reservoirs, and demonstrate the capabilities and limitations of borehole gravity and its potential use within a revised reservoir surveillance plan.
We show examples of forward modelling data from reservoirs with varying fluid displacement mechanisms. Reservoir porosity and saturation data are used to model the predicted three-component (i.e., vector) gravity anomaly (gz, gx, and gy) responses along the wellbore in a variety of wells as the fluid-water front progresses through the field. The modelling included both producing wells and injector wells. The paper will present a description of a forward modeling workflow, simulation studies based on real reservoir data, and the validating measurements.
The paper examines the results of the forward modelling and compares the results with the sensitivity of the new three-axis borehole gravity sensor. The results will show that a wireline deployed three-axis gravity tool with a targeted noise floor of ≈5 μGal will provide additional important surveillance to constrain reservoir models as well as provide vital information to help reduce uncertainty when actively managing waterfront movement (sweep) and secondary recovery and detecting early breakthrough of water; and for monitoring and adjusting strategy when producing through reservoir depressurization. The described workflow is seen as very important for any future survey planning to understand the time-lapse gravity signal and the feasibility of time-lapse gravity surveillance under different reservoir conditions.
A three-axis borehole gravity tool with a form factor enabling it to be deployed through cased hole and into deviated and horizontal wells is completely novel and has not been presented previously. A workflow that understands survey feasibility and optimal survey-time intervals is novel. A systematic and comparative study of three-axis borehole gravity responses through modelling of a reservoir is novel and has limited previous work.
Al-Obaidli, Asmaa (KOC) | Al-Nasheet, Anwar (KOC) | Snasiri, Fatemah (KOC) | Al-Shammari, Obaid (KOC) | Al-Shammari, Asrar (KOC) | Sinha, Satyendra (KOC) | Amjad, Yaser Muhammad (Schlumberger) | Gonzalez, Doris (BP) | Gonzalez, Fabio (BP)
The Magwa-Marrat field started production early 1984 with an initial reservoir pressure of 9,600 psia Thirtysix (36) producer wells have been drilled until now. By 1999, when the field had accumulated 92 MMSTB of produced oil and the reservoir pressure had declined to 8000 psia, the field was shut-in until late 2003 due to concerns on asphaltene deposition in the reservoir that could cause irreversible damage and total recovery losses. The field was restarted in 2003 an it has been in production since then. By April 2018 the field had produced 220 MMSTBO, with the average reservoir pressure declined to 6,400 psia. As crude oil has been produced and the energy of the reservoir has depleted, the equilibrium of its fluid components has been disturbed and asphaltenes have precipitated out of the liquid phase and deposited in the production tubing. There is a concern that the reservoir will encounter asphaltene problems as the reservoir pressure drops further. The objective of this manuscript is to present the process to understand the reservoir fluids behavior as it relates to asphaltenes issues and develop a work frame to recognize and mitigate the risk of plugging the reservoir rock due to asphaltenes deposition with the end purpose of maximizing recovery while producing at the maximum field potential Data acquired during more than 30 years have been integrated and analyzed including 22 AOP measurements using gravimetric and solid detection system techniques, 17 PVT lab reports, 1 core-flooding study and 1 permeability/wettability study. Despite the wide range of AOP measured in different labs, it was possible to determine that the AOP for the Magwa-Marrat fluid is 5,600 500 psia and the saturation pressure is 3,200 200 psia. Results of this fluids review study indicates that it might be possible to deplete the reservoir pressure below the AOP while producing at high rates.
This paper covers the development of a key component of an internal system to report invisible lost time (ILT) metrics across drilling operations. Specifically this paper covers the development of a generalizable rig state engine based on the application of supervised machine learning. The same steps used in the creation of the production rig state engine are appled here to a smaller data set to demonstrate both the tractability of the problem and the methods used to create the rig state engine in the production system.
The project objective was to provide efficiency and engineering metrics in a central repository covering operated regions. The system is designed to require minimal user configuration and management and provides both historic and near real time analysis to deliver a rich resource for offset comparison and benchmarking.
Identifying rig-state is at the heart of every performance and engineering analysis system. This can be thought of as a machine learning classification problem. A large supervised learning set was constructed and used to train classification models which were compared for accuracy. A key success metric was the ability to generalise the selected model across different operations. Output from the rig-state classifier was then used to derive KPI data which was presented through a web based front end. A pilot system was then developed using agile principles allowing for rapid user engagement. Testing demonstrated that the system can support all real time operations within the company simultaneously and rapidly process historic well data for offset benchmarking. The cloud-based architecture allows rapid deployment of the system to new groups significantly reducing deployment costs. The system provides a foundation for onward data science and more advanced functionality.
Minimal configuration, cloud storage and processing, combining contextual data with real-time rig data, near-real-time and historic analysis capabilities, rapid deployment, low cost, high accuracy and consistent metrics are all key and proven value drivers for the system. The output data is aso a valuable resource for additional machine learning and data science projects.
Sawaryn, Steven J. (Consultant) | Wilson, Harry (Baker Hughes, a GE company) | Bang, Jon (Gyrodata Incorporated) | Nyrnes, Erik (Equinor ASA) | Sentance, Andy (Dynamic Graphics Incorporated) | Poedjono, Benny (Schlumberger) | Lowdon, Ross (Schlumberger) | Mitchell, Ian (Halliburton) | Codling, Jerry (Halliburton) | Clark, Peter J. (Chevron Energy Technology Company) | Allen, William T. (BP)
The well-collision-avoidance separation rule presented in this paper is a culmination of the work and consensus of industry experts from both operators and service companies in the SPE Wellbore Positioning Technical Section (WPTS). This is the second of two papers and complements the first paper, SPE-184730-PA (Sawaryn et al. 2018), which described the collision-avoidance management practices. These practices are fundamental in establishing the environment in which a minimum allowable separation distance (MASD) (in m) between two adjacent wells can be effectively applied. A standardized collision-avoidance rule is recommended, complete with parameter values appropriate to the management of health, safety, and environment (HSE) risk, and benchmarks for testing it. Together, these should help eliminate the disparate and occasionally contradictory methods currently in use.
The consequences of an unplanned intersection with an existing well can range from financial loss to a catastrophic blowout and loss of life. The process of well-collision avoidance involves rules that determine the allowable separation and the management of the associated directional planning and surveying activities. The proposed separation rule is dependent on the pedal-curve method and is expressed as a separation factor, a dimensionless number that is an adjusted center-to-center distance between wells divided by a function of the relative positional uncertainty between the two. The recommended values for the rule’s parameters result from a comparison of various industry models and experience. The relationships between key concepts such as the MASD and allowable deviation from the plan (ADP) are discussed, together with their interpretation and application. The dependency on the error distributions of the survey-instrument performance models used to establish the tolerance lines is also discussed.
The consequences of implementing a standardized separation rule across the industry are far-reaching. This affects slot separations, trajectories, drilling practices, surveying program, and well shut-in. We show how the MASD can be related to a probability of crossing and being in the unacceptable-risk region of an offset well. We show why this qualification is required for safe drilling practices to be preserved. Examples are presented in Appendices A through D to help the reader validate the calculations and the directional-drilling software necessary to perform them. The geometrical and statistical limitations of the methods are explained and areas are highlighted for further work. The methods outlined here, taken together with SPE-184730-MS, will improve efficiency in planning and executing wells and promote industry focus on the associated collision risks during drilling. The WPTS also supports the current development of API RP 78, Recommended Practices for Wellbore Positioning. Mathematical derivations or references are shown for all the calculations presented in the paper.
When waxy oil is transported through a pipeline and the pipeline operating temperature drops below the waxappearance temperature (WAT), the wax will precipitate and eventually deposit onto the pipeline's interior surface if a temperature gradient between the bulk fluid and the pipe wall exists. However, because of various operational factors, routine pigging might be delayed for an extended period, thus allowing the wax deposit to accumulate. When this occurs, progressive pigging is required to gradually remove the wax accumulation. Typically, it starts by launching a bore-finding pig (BFP), as shown in Figure 1, followed by pigs with progressively increasing diameters until the routine pig can be fully resumed. An example of a series of progressive pigs and an example of an intermediate cleaning (IC) pig are shown in Figs. 2 and 3, respectively.
In past years, the industry has focused on ensuring that cement is efficiently placed in the wellbore and that it does not become mechanically damaged during the life of the well. However, few efforts have been made to determine how cement mechanical integrity (CMI) relates to cement hydraulic integrity (CHI) (i.e., evaluating the flow rate that could occur through the cement barrier), even though CHI is one of the main objectives of placing a cement plug in a wellbore.
The analysis of hydraulic integrity requires that a CMI model be used to compute the state of stress and pore pressure in the cement and to estimate which type of mechanical failure might occur during the life of the well. It also requires that a CHI model be integrated with the CMI model to estimate the rate of fluid that might flow through a cement barrier, should it mechanically fail. This provides the engineer with insight into the long-term integrity of a cement plug.
This paper describes the work conducted on CMI/CHI models for cement plugs, and it presents a sensitivity analysis that demonstrates the value of an integrated CMI/CHI model. The study indicates that (1) well geometry, cement properties, reservoir pressures, cement heat of hydration, and fluid properties are required inputs for proper analysis; (2) the changes of stresses and pore pressure over time need to be computed along the length of the cement plug, with sensitivity analysis to consider the existing uncertainties; (3) a cement plug might preserve its sealing capability, even if the CMI model shows the existence of a microannulus (e.g., when the fluid viscosity is very high); and (4) a cement plug might lose its sealing capacity, even if the CMI model shows no induced defect (e.g., when a microannulus is propagated as a hydraulic fracture).
These last two observations are important because they show that what a CMI model cannot predict, a CHI model can.