SPE Drilling & Completion

Vol. 35 // No. 1          March 2020

Executive Summary


At the International Drilling Conference organized by IADC and SPE (Galveston, Texas, USA, March 2020), I met one of our authors. He told me a story and I would like to share it. He submitted his paper to SPEDC in October 2019 and received peer-review comments from three technical reviewers and associate editor within 25 days. The several-pages-long review comments were very professional and helped him to revise the paper, and the paper quality was improved in many aspects. He really appreciated the efforts made by our technical review team. In fact, SPEDC receives approximately 200 submissions annually. Each submitted paper is carefully peer reviewed by a group of experts from industry and academia. Efforts have been focused on reducing the number of days from submission to first decision without sacrificing the review quality.

Drilling


The analysis of the gas extracted from drilling mud is crucial for hydrocarbons identification and formation assessment. There are many variables affecting the gas-extraction and analysis processes: gas concentration in the mud, stirring velocity, mud-flow rate and temperature, and ditch-line flow rate and pressure. The authors of Optimization of the Gas-Extraction Process in a New Mud-Logging System find that when the stirring velocity is 1,680 rev/min and the mud-flow rate is 1.0 L/min, the gas-extraction efficiencies are highest and most stable.

The use of advanced solid-state gyroscopic sensors has become both a viable and practical option for high-accuracy wellbore placement, with the potential to outperform traditional mechanical gyroscopic systems. In the paper entitled The Combination of Solid-State Gyroscopic and Magnetic Surveys Provides Improved Magnetic-Survey Data and Enhanced, the authors propose methods incorporating a new gyroscope tool capable of enhanced measurement accuracy compared with the highest performance mechanical gyroscopic system currently in service. Service providers may be interested in reconsidering current survey practices and examining how the new gyroscopic-survey tools can best be used for wellbore surveying and real-time wellbore placement.

Formation damage induced by polysulfonate oil-mixture drill-in fluid is considerable in a deep-fractured tight-sandstone oil reservoir in northern Tarim Basin. It is mainly attributed to the inadequate understanding of multiscale damage mechanisms, unique engineering, and geological conditions of these reservoirs. To fill this gap, an engineered formation-damage-control (FDC) drill-in-fluid technology is developed in the paper entitled An Engineered Formation-Damage-Control Drill-In Fluid Technology for Deep-Fractured Tight-Sandstone Oil Reservoir in Northern Tarim Basin. In the FDC drill-in fluid field testing, short drilling cycle, less drill-in-fluid loss, and low damage are observed.

In Automated Pressure Control for UBD Operations: Case Study and Field Validation, the authors present a case study where the combination of sensors for managed-pressure-drilling (MPD) and under-balanced drilling (UBD)  and an automated pressure control system helped to drill a fractured-carbonate well located in the Archinskoe Field in western Siberia. The field consists of naturally fractured carbonate formations into which it is challenging to drill deep with conventional drilling methods. MPD/UBD enabled the drilling of significantly longer production sections than had been previously achieved for this formation.

The wellbore cleanout operation is often associated with nonproductive time and significantly adds to the operational cost. The authors of Wellbore Cleanout in Inclined and Horizontal Wellbores: The Effects of Flow Rate, Fluid Rheology, and Solids Density develop a model to predict the required fluid-circulation rate and time to efficiently remove solids from the wellbore and optimize the cleanout operation. The effects of solid density, flow rate, inclination angle, and fluid type on the cleanout operation were investigated by measuring bed erosion and hole-cleaning efficiency. A dimensionless correlation incorporating the effects of all tested flow parameters has been developed to predict bed height or circulation time with reasonable accuracy.

Cuttings Transport Modeling—Part 2: Dimensional Analysis and Scaling is a follow-up to part one of the research effort on cuttings transport modeling published in SPEDC (Vol. 33, No. 2, 2018). The authors provide a generic, comprehensive, and consistent set of nondimensional quantities characterizing cuttings transport. The paper encompasses the major fluid material functions currently in use in the petroleum industry and in the present form relates the cuttings-bed area fraction to a set of familiar nondimensional numbers. The authors account for the non-Newtonian or, more precisely, shear-thinning and yield behavior of the drilling fluid by using non-Newtonian scaling concepts for generalized Newtonian fluids available in the literature.

Completion


The current enhanced-oil-recovery and carbon-sequestration schemes involve the injection of CO2 directly into the well. The injection causes dissolution of CO2 in the formation fluid, leading to the formation of H2CO3, which lowers the pH of the fluid surrounding the cement. The formation of H2CO3 results in rapid degradation of cement and cement damage. It becomes imperative to understand the degradation mechanism of cement and methods to reduce the damage, such as the use of special additives to improve the resistance of cement to an acid attack. In Carbonic Acid Resistance of Hydroxyapatite-Containing Cement, the authors present the application of hydroxyapatite as a cement additive to improve the H2CO3 resistance of oilwell cement. Experimental results show that a hydroxyapatite-containing cement formulation has acceptable slurry properties for field applications and better H2CO3 resistance compared with conventional cement.

Understanding the interactions between salt and surfactant and their behaviors in different types of reservoirs is essential in designing completion fluids. The authors of Investigation of the Interaction of Surfactant at Variable Salinity with Permian Basin Rock Samples: Completion Enhancement and Application for Enhanced Oil Recovery investigate the interactions of surfactant and salinity in different ULR lithologies in west Texas, USA, and determine the relationship between the experimental parameters and oil recovery to provide potential screening criteria for completion-fluid design. This study has a practical applicability for maximizing efficiency in the stimulation fluid design process.

The water-hammer phenomenon occurs when flow velocity decreases suddenly to zero because of sudden value closure. The resulting high pressure can be destructive. As a result of the water-hammer phenomenon, swab- and surge-pressure waves propagate either upstream or downstream of a point in a well where a sudden change in fluid velocity takes place. In the paper entitled Computation of Surge-Pressure-Wave Propagation During Cementation Process, the authors present a method of modeling surge pressures and wave propagation that can occur during well execution. A transient-state physical model is built to compute pressure-wave propagation through drillstring, casing, and open hole to predict the amplitude of a surge-pressure wave and to warn when a fracture might occur in the formation, to avoid mud losses and NPT.

Radial jet drilling is an unconventional drilling technology that uses high-pressure liquid jet to drill multiple radial laterals. It is a cost-effective alternative for bypassing damage zones near the wellbore, restimulating the production of old wells, and developing unconventional reservoirs. The authors of A Feasible Method for the Trajectory Measurement of Radial Jet Drilling Laterals propose a measuring system and a mini-tool for attitude measurement and motion-state recognition. A reckoning method is proposed to obtain the trajectory parameters by using the recorded data of the tool and the operational data of the coiled tubing. The accuracy of the measured length, inclination, and azimuth is respectively high.

Shilin Chen, SPE Drill & Compl Executive Editor,
Chief Technical Advisor, Halliburton Drill Bits and Services