Multi-Stage Hydraulic Fracturing Completion Design Based on Ball-and-Sleeve Method

This paper proposes a completion that can allow fracturing four zones in a single trip in the well called “Y” (for confidential reasons) of the field named “X” (for confidential reasons). The steps to design a well completion for multiple fracturing are first to select the best completion method then the required equipment and the materials that it is made of. After that, the completion schematic must be drawn by using Power Draw in this case, and the summary installation procedures explained. The data used to design the completion are the well trajectory, the reservoir data (including temperature, pressure and fluid properties), the production and injection strategy. The results suggest that multi-stage hydraulic fracturing can be done in a single trip by using the ball-and-sleeve method. Metallurgy and hydrogenated nitrile are sealing elementary constituent of chromium which are essential materials found in alloy with 13% of chromium

The crustal structure along the Mbere trough in South Adamawa (Cameroon) from spectral analysis and gravity modelling

The Mbere Cretaceous trough is located in the southern part of the Adamawa province. A gravity interpretation based on data obtained from three NW-SE profiles on the residual anomaly map has been carried out using a 2.5D modelling program. Spectral analysis has been used to estimate the depth of geological structures. The results obtained show that the metamorphic formations consist of gneiss and migmatite which are located in the north of the trough at a mean depth of 9 km. The gradient observed on the Bouguer anomaly map along the trough might not only be due to the northern fault but also due to the contact between the gneiss (and migmatite) and granite under the trough. The thickness of sediments along the trough varies between 1500 and 2250 m with a minimum at Yariban and a maximum at Djohong. The trough is bounded on its sides by faults related to the Central African Shear Zone. Basaltic rocks associated with the Cameroon Volcanic Line are present as intruded rocks lying at a minimum depth of 7200 m. Keywords: bouguer anomaly, residual anomaly, fault, trough Global Journal of Pure and Applied Sciences Vol. 12(1) 2006: 111-11

A Turbo Pascal 7.0 program to fit a polynomial of any order to potential field anomalies based on the analytic least squares method

An anomaly separation program for gravity (or magnetic) data in prospecting domain is presented. It can be applied to the gravity or magnetic anomaly separation of degree up to three and allows the management of up to 1200 data. Its implementation requires a Turbo Pascal surrounding through a TP7 list on the main root of the computer. The results obtained after execution of the program can be displayed, printed or stocked in a data file. In order to test the program, we have compared our results with those obtained from a Fortran program written by Radhakrisha and Krishnamacharyulu (1990) using the least squares method. The advantage of using our program is that a great number of data can be handled even for a local study, the execution is rapid and the accuracy is greatly improved upon. African Journal of Science and Technology Vol.4(2) 2003: 1-

Moho Discontinuity Depth Estimates for the Cameroon Volcanic Line from Gravity Data

In this work, the Moho depth in a part of the Cameroon Volcanic Line (CVL) between the latitudes 3°30´ to 6°33´N and the longitudes 8°50’ to 11°27’E, has been estimated covering two distinct regions: the Mount Cameroon and the Bamenda by the use of polynomial separation of gravity data and spectral analysis along two profiles. The Moho is uplifted in the Mount Cameroon region, where the crust is thinned to about 24 km. In the Bamenda region, the crustal thickness is found to be normal at about 31 km. The high positive gravity anomalies of up to 100 m Gal observed in this area indicate the thinning of the crust in the Mount Cameroon region. Seismic and gravity data indicate a crustal thickness of 30-34 km along the continental parts of the Cameroon Volcanic Line, except in the Adamawa plateau, where the crust’s thickness ranges between 20-23 km. The crustal thickness of about 31 km in the Bamenda region is an evidence of perfect isostatic compensation, which suggests a deep seated source for the negative anomaly, resulting in a general asthenospheric uplift along the Cameroon Volcanic Line

Hydraulic parameters evaluation of the Pan-African aquifer by applying an alternative geoelectrical approach based on vertical electrical soundings

Para este estudio se realizaron cincuenta Sondeos Eléctricos Verticales (SEVs), de los cuales en 14 sitios se tenía información de muestreos de agua. Estos sondeos se interpretaron para determinar los parámetros hidráulicos del acuífero Pan[1]Africano en la región de Adamawa-Camerún, y estos fueron Transmisividad (T) y Conductividad Hidráulica (K). El enfoque utilizado es efectivo y aplicable a otras áreas similares, si se toman las suposiciones adecuadas. La resistencia transversal (RT) del acuífero oscila entre 24 y 31,350 Ω.m² con un promedio de 7476 Ω.m²; la resistencia transversal modificada (RTM) oscila entre 1526 y 28209 Ω.m² con un promedio de 7873 Ω.m²; la Transmisividad (T) oscila entre 4 y 17,4 m²/día con un promedio de 7.23 m²/ día y una desviación estándar de 3.42 m²/día; y la Conductividad Hidráulica (K) varía de 0,07 a 0,74 m/día con una media de 0,31 m/día y una desviación estándar de 0,17 m/día. doi: https://doi.org/10.22201/igeof.00167169p.2018.58.2.196

A geostatistical re-interpretation of gravity surveys in the Yagoua, Cameroon region

Desde 1960 se han realizado diversos estudios de gravedad en la región Yagoua del norte de Camerún. Se recabaron datos de gravedad en una área amplia que abarca aproximadamente 11.628 km2. Estos datos son insuficientes, irregulares, dispersos y no permiten eficientemente continuaciones ascendentes y descendentes del campo gravitatorio, derivadas y otras operaciones que requieren datos reticulados regulares. Algunas anomalías en el mapa Collignon (1968) pueden correlacionarse con la estructura geológica que se conoce, pero no aparecen en los mapas de Louis (1970) y Poudjom et al. (1996). Para producir los datos de gravedad reticulares regulares y mejor control de las anomalías, derivadas de estructuras geológicas, se aplicó el método de Kriging a una línea de base de datos-188. Se ensayaron para este propósito varios modelos de variograma. Se encontró que un modelo esférico era la mejor opción; se ha elaborado un nuevo conjunto de datos Kriging con unos 10.100 resultados y un nuevo mapa con los datos Kriged Bouguer. Este mapa contiene anomalías positivas en las zonas Maroua-Mindif y Maga (1968) en el mapa Collignon, que no estaban presentes en los mapas de Louis (1970) y Poudjom et al. (1996). Las anomalías positivas de Guibi-Doukoula y Yagoua, que no se encuentran separados en los mapas de Louis (1970) y Poudjom et al. (1996), aparecen claramente distintas a como fueron previstas por Collignon (1968). Los nuevos resultados pueden ser utilizados para los estudios gravimétricos posteriores. doi: https://doi.org/10.1016/S0016-7169(13)71483-

Validation of gravity data from the geopotential field model for subsurface investigation of the Cameroon Volcanic Line (Western Africa)

Abstract Belonging to the Cameroon Volcanic Line (CVL), the western part of Cameroon is an active volcanic zone with volcanic eruptions and deadly gas emissions. The volcanic flows generally cover areas and bury structural features like faults. Terrestrial gravity surveys can hardly cover entirely this mountainous area due to difficult accessibility. The present work aims to evaluate gravity data derived from the geopotential field model, EGM2008 to investigate the subsurface of the CVL. The methodology involves upward continuation, horizontal gradient, maxima of horizontal gradient–upward continuation combination and Euler deconvolution techniques. The lineaments map inferred from this geopotential field model confirms several known lineaments and reveals new ones covered by lava flows. The known lineaments are interpreted as faults or geological contacts such as the Foumban fault and the Pan-African Belt–Congo craton contact. The lineaments highlighted coupled with the numerous maar lakes identified in this volcanic sector attest of the vulnerability of the CVL where special attention should be given for geohazard prevention