Najmah formation in Kuwait is known having rich kerogen rock that has potential of the hydrocarbon gas. The formation contains the mixtures limestone - dolomitic - clay and kerogen and has low to medium porosity. The presence of the fractures is main driver of the rock permeability. Borehole images is required to understand the fractures development and geological features in Najmah formation.
High formation pressure and risk of wellbore stability associated with clay mineral, suggests of using synthetic oil base mud with high mud weight 16 lb/gal. The hole size increases to 9 ¼-in. from the conventional 8 ½-in. for the well bore stability purpose. Conventional wireline electromagnetic (EM) micro-resistivity images worked with oil base mud and heavy mud weight have been used to analyze the fracture presence and geological characterization in Najmah formation. However, upcoming development strategy in the field is high deviated well construction which limit the acquisition of the images logging with conventional wireline.
The recent new development of LWD high definition multi measurement images in oil-based mud attracts the oil operator to utilize it for the further application in high deviated well. The apparatus consists of electromagnetic resistivity images and ultrasonic images and has diameter of 8.25" for hole size of 8.5in. The unique drilling environment with heavy mud weight and variable stand-off stretches the operating envelop of the technology to the its maximum boundary. The high stand-off and heavy mud weight attenuated the signal of electromagnetic impedance come from formation. This paper will discuss a comparison between conventional electromagnetic resistivity images conveyed by wireline with the new generation multi-measurement of LWD imager in synthetic oil base mud in unconventional reservoir Najmah Kerogen formation. The main objective for the study is to have lesson learnt and assessing the quality of the multi-measurement LWD image's data with given stretch operating condition. The solution of the minimizing the effect high mud attenuation to the images acquired due to variable stand-off and heavy mud weight will be discussed.
