Sand production in oil and gas wells is badly affecting production rates, damaging downhole and surface equipment. Knowledge of source of sand production and its amount can prolong well life by performing timely remedial operations. Nowadays, companies rely on stress analysis and numerical models to predict source of sand production in wells producing from several layers commingled and at the same time amount of sand production is measured on surface with separators. On the other side, wireline sand detection tool allows to quantify and locate source of sand production downhole as well produces, and when run in combination with production logging tool string, to quantify multiphase inflow profile into the well simultaneously. Most of the wells on Dzheitune (LAM) field, located offshore Caspian Sea, were completed with dual tubing at the beginning of field development. Over the time, depletion in reservoir pressure caused formation failure in A-sand reservoir and wells producing from this formation started to produce sand. Some wells had to be recompleted by pulling out of hole dual string completion and running in hole single tubing with sand screens across existing perforations. Before pulling dual tubing, some wells were logged with slim sonic tool to locate top of sand accumulation in casing to long tubing annulus. This information was used to determine depth for tubing cut, before pulling it out of hole; whenever such operation was required. Most of the newly drilled wells are completed with single tubing having sand screens. Field examples, presented in this paper, describe principles of data acquisition with sand detection tool when run in combination with production logging string, and results of logging in slightly deviated wells completed with sand screens. Comparison of multi-phase inflow profiles with source of sand production showed that most of sand is being produced through hotspot in sand screens; i.e. eroded hole that was generally located across topmost section of the screens in almost all the wells that were logged. Logging results are then used for planning remedial operations to pull tubing out of hole and to replace damaged screens.

Good cement bond at the casing-cement and cement-formation interfaces is essential for effective zonal isolation. Poor bonding can lead to underground fluids and gases to enter the annulus and create sustained casing pressure (SCP), jeopardising the working envelope of the well and limiting its production. One of the causes of a poor cement-formation bonding is attributed to a cement shrinkage. Cement systems that expand after setting can help improve primary cementing job results by sealing microannulus. The enhanced bonding is the result of enhanced shear bond and adhesion of the cement against the pipe and formation. Cement expansion is achieved by addition of the expanding additives into cement system. The mechanism of expansion is based on set cement volume growth over initial volume post setting. This is driven either by gas bubbles created during chemical reaction or by crystal growth within set cement matrix. Careful optimization of the cement slurry designs with an addition of the expansion additives to conventional and complex blend systems allowed greatly improving the cement bond evaluation log results without compromising other mechanical properties of cement. This paper outlines the successful application of expanding cement to seal different sizes of wellbore; the study evaluates the effect of the expansion by comparing the cement evaluation log from numerous cementing jobs. Examples included in the comparison are cemented production strings (casings and liners) with different types of cement systems used across 9 5/8-in. production casings and 7-in. and 4 1/2-in. production liners.

Detailed cement evaluation with good azimuthal coverage is paramount for many wells in Chinarevskoe field, western Kazakhstan, as it affects perforation placement for acid treatment of thinly layered formation that is very heterogeneous, with varying permeability, reservoir pressure and water saturation. Analysis in these wells is performed not only to evaluate cement quality, but also to relate it to casing centricity with respect to formation or outer casing walls to help reaching objectives for cementing jobs in future wells. Cement evaluation with wireline tools is one of the primary means for determining whether the objectives of a cementing job have been reached once the job is finished. Several logging techniques are currently available for measuring cement quality, including sonic cement bond logs (CBL) and ultrasonic logs. These logs are affected by a microannulus to various extents, and this can make a big difference in our interpretation of cement placement quality. The sonic CBL and ultrasonic imaging log were run to evaluate cement quality in wells in Chinarevskoe field. Most of the wells exhibit the presence of a microannulus between the casing and cement sheath that develops just after the cementing job is completed. We observe that sonic CBL logs are affected by the presence of the microannulus. Cement evaluation is further complicated by the presence of contaminated cement where the acoustic impedance of the mud is close to the acoustic impedance of the contaminated cement. In these wells, a new generation cement evaluation service with enhanced ultrasonic measurements was deployed. A comparison of the results with traditional ultrasonic and sonic measurements shows that analysis of the enhanced ultrasonic logs improves cement evaluation in the presence of microannulus.

In a gas-condensate field in Kazakhstan, advanced production logging tools and techniques were used to assess well productivity, characterize flow profiles, and determine hydrocarbon saturation pressure at downhole well flowing conditions. The exploration and appraisal wells produce from a complex carbonate reservoir. To assess well productivity, each well was perforated and tested across each formation separately. Intervals to perforate were selected based on petrophysical log evaluation, core analysis, and the results of selective testing with a wireline formation tester. While testing these wells, production logging data were acquired at different downhole flowing pressures and a detailed analysis of gas holdup measurements with optical probes enabled the determination of the dew-point pressure of produced gas-condensate. Such analysis is beneficial, especially when pressure/volume/temperature (PVT) analysis of produced fluid is not yet available for exploration and appraisal wells. Further comparison of wireline-acquired PVT samples showed good agreement between measured dew-point pressure from the production logging tool and PVT laboratory analysis results. In the field, production logging helped in understanding well behavior by locating producing intervals in wells that have more than one perforated interval or produce from only one long perforated interval that has several producing intervals. Field experience verifies that a properly planned and executed production logging operation can yield invaluable early information for key investment decisions and complement the results of the well test.

Improvements in ultrasonic cement evaluation technology are increasing operational efficiency and reliability and extending the operating envelope into extreme environments with heavy muds and larger and thicker casings. Tool hardware, software, and firmware have been substantially redesigned and optimized to increase acquisition efficiency and data quality output. One key aspect is the complete redesign of various ultrasonic transducers to enable acquisition in the heaviest, highly attenuative muds. A specially designed transducer for thick casings and large rotating logging heads are pushing the thickness and diameter envelope to cover almost all possible scenarios. Yard tests were conducted to emulate extreme downhole conditions in a controlled way: A casing filled with heavy mud (2-g/cm3 synthetic oil-based mud [SOBM]) and cemented in an eccentered position inside a simulated formation was tested with two complementary ultrasonic techniques, pulse-echo and flexural wave imaging. These tests demonstrated the proper performance of both measurements despite the highly attenuative logging mud and made it possible to determine annulus material impedance, casing centralization, and location of the position of a "simulated measurement cable" (such as fiber-optics bundles) cemented inside the annulus. Through two field tests we further confirmed the efficiency improvements concerning logging speed (i.e. software/firmware). Logs have been obtained in extremely heavy mud environments and 26.7-mm (1.05-in.) thickness casing. These new developments in ultrasonic cased hole technology enable cement evaluation and pipe inspection in environments of the heaviest muds and casings of extremely large size and greater thickness, thus augmenting the industry's ability to diagnose well integrity while helping to reduce uncertainty and risk in well construction or before abandonment operations.